Beet yellows virus resistance

Abstract

The present disclosure relates to plants, plant parts, or plant cells resistant to Beet Mild Yellowing Virus (BMYV) having at least one quantitative trait loci (QTL) associated with resistance to BMYV. The disclosure also relates to methods of selecting, identifying, and producing plants, plant parts, or plant cells resistance to BMYV, which reduce yield loss or increase yield for sugar production. Furthermore, the present disclosure relates to nucleic acid molecules which impart resistance to a pathogen in plants, plant parts, and plant cells, in particular of the genus Beta.

Description

BEET YELLOWS VIRUS RESISTANCECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Patent Application No. 63 / 482,786, filed February 1, 2023, entitled “Beet Yellows Virus Resistance,” the disclosure of which is hereby incorporated by reference in its entirety.FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to plants, plant parts, and plant cells conferring traits of resistance to virus yellows and methods of producing the same. Further, the disclosure relates to nucleic acid molecules for identifying resistant traits, and nucleic acid molecules that impart resistance to pathogens in plants, plant parts, and plant cells.REFERENCE TO AN ELECTRONIC SEQUENCE LISTING

[0003] The sequence listing xml associated with this application is provided electronically in xml file format and is hereby incorporated by reference into the specification. The contents of the electronic sequence listing (DLFS_001_01WO_SeqList_ST26.xml; Size: 77,623 bytes; and Date of Creation: January 26, 2024) are herein incorporated by reference in its entirety.BACKGROUND OF THE DISCLOSURE

[0004] Sugar beet (Beta vulgaris subsp. vulgaris) is an important root crop that accumulates sugar and provides about 30% of the world’s annual sugar production and is used as one of sources for bioethanol and animal feed. With sugar beet cultivation advanced, pests and diseases became a major threat for sugar production, restricting the agronomic yield potential of the crop (Bennett, et al., (1956) Effects of virus yellows on sugar beet with a consideration of some of the factors involved in changes produced by the disease. American Society of Sugar Beet Technologists Journal, 9, 479-494). Among many, one of the most economically important viral diseases is virus yellows (VY), which is caused by a complex of different aphid- transmissible virus species.

[0005] The beet yellowing disease appears in circles in the fields, in the form of lightening and then yellowing of the lamina between the veins of leaves. The leaves thicken and become brittle . These symptoms first form limited areas of infection in the fields and then rapidly spread throughout the entire field. Yellowing viruses can cause yield losses of 50 % when it infects the crop in early June. Infection reduces the photosynthetic area of leaves reducing yield and sugar content, which significantly impacts the world’s sugar production and related food chainsin human beings and animals. The disease is widespread across all sugar beet regions of Europe. If it strikes early in the season, it can be the cause of significant yield loss, reduced sugar content and lower industrial quality.

[0006] To control the yellowing viruses, insecticides from the neonicotinoid class have been used to combat the vector (aphid) since 1990s. Due to costs, safety, and environmental impact of pesticides, as well as the development of resistance in the target organisms, pesticides from the neonicotinoid class have been banned in sugar beet cultivation since 2019 in most of the sugar beet-producing countries in Europe (Luterbacher, et al., (2004) Sources of resistance to diseases of sugar beet in related Beta germplasm: I. Foliar diseases. Euphytica, 139, 105-121).

[0007] Therefore, there is an urgent need for identifying traits of resistance to yellowing viruses from resistant plant varieties and transferring such traits to susceptible varieties. Also, there is a need for producing and using sugar beet plants having such traits of resistance to beet yellows virus.SUMMARY OF THE DISCLOSURE

[0008] The following embodiments and aspects thereof are described in conjunction with compositions, products, plants, and methods which are meant to be exemplary, not limiting in scope.

[0009] In some aspects, the present disclosure relates to a. Beta vulgaris subsp. vulgaris plant, plant part, or plant cell resistant to Beet Mild Yellowing Virus (BMYV), wherein said plant, plant part, or plant cell includes at least one Quantitative Trait Loci (QTL) associated with resistance to BMYV, wherein said QTL is selected from the group consisting of QTL1, QTL2, and QTL3, and wherein QTL1, QTL2, and QTL 3, are obtainable from Beta vulgaris subsp. vulgaris line 21000003-71, representative seed of which has been deposited under NCIMB number 44107.

[0010] In some aspects, the present disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell, wherein QTL1 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV504245, PBV125552, PBV291217, PBV369685, and PBV261963, wherein: PBV504245 is a C to G substitution corresponding to position 1050427 of chromosome 1 of the Refbeet 1.5 reference genome, PBV125552 is a G to A substitution corresponding to position 3069972 of chromosome 1 of the Refbeet 1.5 reference genome, PBV291217 is a G to A substitution corresponding to position 4315236 of chromosome 1 of the Refbeet 1.5 reference genome, PBV369685 is an Ato G substitution corresponding to position 4330737 of chromosome 1 of the Refbeet 1.5 reference genome, and PBV261963 is an Ato T substitution corresponding to position 4356001 of chromosome 1 of the Refbeet 1.5 reference genome. In some aspects, QTL1 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV757437, PBV638722, and EPBV6296, wherein: PBV757437 is a G to A substitution corresponding to position 17043 of chromosome 1 of the Refbeet 1.5 reference genome, PBV638722 is an A to G substitution corresponding to position 2645728 of chromosome 1 of the Refbeet 1.5 reference genome, and EPBV6296 is a T to C substitution corresponding to position 1117040 of chromosome 1 of the Refbeet 1.5 reference genome.

[0011] In some aspects, the present disclosure relates to a. Beta vulgaris subsp. vulgaris plant, plant part, or plant cell, wherein QTL2 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV577030, PBV562771, PBV573138, PBV273480, and PBV821051, wherein: PBV577030 is an A to G substitution corresponding to position 5742753 of chromosome 4 of the Refbeet 1.5 reference genome, PBV562771 is a G to A substitution corresponding to position 9767085 of chromosome 4 of the Refbeet 1.5 reference genome, PBV573138 is an A to G substitution corresponding to position 10271308 of chromosome 4 of the Refbeet 1.5 reference genome, PBV273480 is a G to A substitution corresponding to position 46718199 of chromosome 4 of the Refbeet 1.5 reference genome, and PBV821051 is a G to A substitution corresponding to position 47855576 of chromosome 4 of the Refbeet 1.5 reference genome.

[0012] In some aspects, the present disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell, wherein QTL3 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV148969, PBV331644, PBV882826, PBV374371, and PBV757436, wherein: PBV148969 is an A to G substitution corresponding to position 436005 of chromosome 8 of the Refbeet 1.5 reference genome, PBV331644 is a G to A substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, PBV882826 is an A to G substitution corresponding to position 7979633 of chromosome 8 of the Refbeet 1.5 reference genome, PBV374371 is a G to A substitution corresponding to position 8822544 of chromosome 8 of the Refbeet 1.5 reference genome, and PBV757436 is an A to C substitution corresponding to position 25201555 of chromosome 8 of the Refbeet 1.5 reference genome. In some aspects, QTL3 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV738292, PBV738293, and EPBV7349, wherein: PBV738292 is a Gtoan A substitution corresponding to position 35831 of chromosome 8 of the Refbeet 1.5 reference genome, PBV738293 is an A to G substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, and EPBV7349 is an A to C substitution corresponding to position 275340 of chromosome 8 of the Refbeet 1.5 reference genome.

[0013] In some aspects, the present disclosure relates to a. Beta vulgaris subsp. vulgaris plant, plant part, or plant cell, further including a fourth QTL (QTL4) associated with resistance to BMYV, wherein QTL4 is genetically linked to at least one marker loci selected from the group consisting of GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV 116271, and EPBV8821, wherein: GRKPBV98281 is a G to A substitution corresponding to position 8040503 of chromosome 2 of the Refbeet 1.5 reference genome, GRKPBV627372 is a C to an A substitution corresponding to position 9433027 of chromosome 2 of the Refbeet 1.5 reference genome, GRKPBV672273 is a G to an A substitution corresponding to position 12212298 of chromosome 2 of the Refbeet 1.5 reference genome, GRKPBV627178 is anA to C substitution corresponding to position 18410288 of chromosome 2 of the Refbeet 1.5 reference genome, GRKPBV 116271 is an A to C substitution corresponding to position 20007280 of chromosome 2 of the Refbeet 1.5 reference genome, and wherein QTL4 is obtainable from Beta vulgaris subsp. vulgaris line 21000003-71, representative seed of which has been deposited under NCIMB number 44107.

[0014] In some aspects, the present disclosure relates to a plant, plant part, or plant cell having resistance to Beet Mild Yellows Virus, wherein the resistance is associated with a reduced load of the Beet Mild Yellows Virus by at least 25% in comparison to a variety lacking QTL1, QTL2, QTL3, and / or QTL4. In some aspects, the resistance is associated with a reduced load of the Beet Mild Yellows Virus by at least 50% in comparison to a variety lacking QTL1, QTL2, QTL3, and / or QTL4. In some aspects, the resistance is associated with a reduced load of the Beet Mild Yellows Virus by at least 75% in comparison to a variety lacking QTL1, QTL2, QTL3, and / or QTL4. In some aspects, the reduced load of the Beet Mild Yellows Virus is determined by an antibody assay. In some aspects, the antibody assay is an enzyme-linked immunosorbent assay. In some aspects, the reduced load of the Beet Mild Yellows Virus is determined by an antibody assay in comparison to a plant, plant part, or plant cell which is genetically essentially identical except for the presence of the resistance to BMYV. In some aspects, the plant, plant part, or plant cell is also resistant against Beet yellows virus (BYV) or Beet chlorosis virus (BChV).

[0015] In some aspects, the present disclosure relates to a plant, plant part, or plant cell, wherein said plant, plant part, or plant cell is heterozygous for at least one of QTL1, QTL2, QTL3, and QTL4. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL1 and QTL2. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL1 and QTL3. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL1 and QTL4. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL2 and QTL3. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL2 and QTL4. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL3 and QTL4. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL1, QTL2, QTL3, and QTL4.

[0016] In some aspects, the present disclosure relates to a plant, plant part, or plant cell, wherein said plant, plant part, or plant cell is homozygous for at least one of QTL1, QTL2, QTL3, and QTL4. In some aspects, the plant, plant part, or plant cell is homozygous for QTL1 and QTL2. In some aspects, the plant, plant part, or plant cell is homozygous for QTL1 and QTL3. In some aspects, the plant, plant part, or plant cell is homozygous for QTL3 and QTL4. In some aspects, the plant, plant part, or plant cell is homozygous for QTL2 and QTL3. In some aspects, the plant, plant part, or plant cell is homozygous for QTL2 and QTL4. In some aspects, the plant, plant part, or plant cell is homozygous for QTL3 and QTL4. In some aspects, the plant, plant part, or plant cell is homozygous for QTL1, QTL2, QTL3, and QTL4.

[0017] In some aspects, the present disclosure relates to a plant, plant part, or plant cell, wherein said plant, plant part, or plant cell is heterozygous for QTL1, and homozygous for at least one of QTL2, QTL3, and QTL4. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL2, and homozygous for at least one of QTL1, QTL3, and QTL4. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL3, and homozygous for at least one of QTL1, QTL2, and QTL4. In some aspects, the plant, plant part, or plant cell is heterozygous for QTL4, and homozygous for at least one of QTL1, QTL2, and QTL3. In some aspects, the plant, plant part, or plant cell is homozygous for QTL1, and heterozygous for at least one of QTL2, QTL3, and QTL4. In some aspects, the plant, plant part, or plant cell is homozygous for QTL2, and heterozygous for at least one of QTL1, QTL3, and QTL4. In some aspects, the plant, plant part, or plant cell is homozygous for QTL3, and heterozygous for at least one of QTL1, QTL2, and QTL4. In some aspects, the plant, plant part, or plant cell is homozygous for QTL4, and heterozygous for at least one of QTL1, QTL2, and QTL3.

[0018] In some aspects, the present disclosure relates to a plant, plant part, or plant cell as described herein, wherein said plant is a fodder beet or sugar beet.

[0019] In some aspects, the present disclosure relates to a plant, plant part, or plant cell plant as described herein, wherein the plant part, or plant cell includes a desirable trait introduced by a method selected from the group consisting of genetic transformation, genome editing, targeted mutagenesis, and induced random mutagenesis. In some aspects, the desirable trait is selected from the group consisting of (i) the H7-1 event conferring glyphosate tolerance, (ii) a mutated ALS gene conferring tolerance against ALS herbicides, (iii) the GTSB77 event conferring glyphosate tolerance, and (iv) the T 120-7 event conferring glufosinate tolerance. In some aspects, the ALS gene encodes an ALS polypeptide containing an amino acid different from tryptophan at a position 569 of the ALS polypeptide. In some aspects, the plant, plant part, or plant cell further includes a Beet Mild Yellowing Virus tolerance trait obtainable from the group of sugar beet varieties including Maruscha KWS and Novalina KWS.

[0020] In some aspects, the present disclosure relates to a plant part as described herein, wherein the plant part is a seed. In some aspects, the seed is technically treated, whereby the technical treatment is selected from the group consisting of polishing, pelleting, incrustation, and coloring. In some aspects, the technical treatment does not include insecticide. In some aspects, the plant part is a commodity plant product. In some aspects, the plant product is a beet.

[0021] In some aspects, the present disclosure relates to a marker for selection of Beet Mild Yellowing Virus resistant plants selected from the group consisting of SEQ ID NO: 1 to SEQ ID NO: 45. In some aspects, the present disclosure relates to a marker for selection of Beet Mild Yellowing Virus resistant plants selected from the group consisting of SEQ ID NO: 52 to SEQ ID NO: 87. In some aspects, the marker utilizes a sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 29, SEQ ID NO: 32, SEQ ID NO: 35, SEQ ID NO: 38, SEQ ID NO: 41, and SEQ ID NO: 44. In some aspects, the marker utilizes a sequence selected from the group consisting of SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 58, SEQ ID NO: 62, SEQ ID NO: 65, SEQ ID NO: 67, SEQ ID NO: 70, SEQ ID NO: 73, SEQ ID NO: 76, SEQ ID NO: 79, SEQ ID NO: 83, and SEQ ID NO: 85.

[0022] In some aspects, the present disclosure relates to a method of using any one of the molecular markers described herein for selection of a plant resistant against a virus selected from the group consisting of Beet Mild Yellowing Virus (BMYV), Beet yellows virus (BYV), and Beet chlorosis virus (BChV). In some aspects, the molecular markers identify at least oneof the Single Nucleotide Polymorphisms present in PBV504245, PBV125552, PBV291217, PBV369685, PBV261963, PBV577030, PBV562771, PBV573138, PBV273480, PBV821051, PBV148969, PBV331644, PBV882826, PBV374371, and PBV757436. In some aspects, the molecular markers identify at least one of the Single Nucleotide Polymorphisms present in PBV757437, PBV638722, EPBV6296, PBV738292, PBV738293, EPBV7349,GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821.

[0023] In some aspects, the techniques described herein relate to a method of identifying a plant, plant part, or plant cell including a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 1 (QTL1), said method including the steps of: screening for the presence of QTL1, wherein QTL1 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV504245, PBV125552, PBV291217, PBV369685, and PBV261963, wherein: PBV504245 is a C to G substitution corresponding to position 1050427 of chromosome 1 of the Refbeet 1.5 reference genome, PBV125552 is a G to A substitution corresponding to position 3069972 of chromosome 1 of the Refbeet 1.5 reference genome, PBV291217 is a G to A substitution corresponding to position 4315236 of chromosome 1 of the Refbeet 1.5 reference genome, PBV369685 is an A to G substitution corresponding to position 4330737 of chromosome 1 of the Refbeet 1.5 reference genome, and PBV261963 is an A to T substitution corresponding to position 4356001 of chromosome 1 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL1. In some aspects, the screening for the presence of QTL1 further includes identifying a plant, plant part, or plant cell having at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV757437, PBV638722, and EPBV6296, wherein: PBV757437 is a G to A substitution corresponding to position 17043 of chromosome 1 of the Refbeet 1.5 reference genome, PBV638722 is an A to G substitution corresponding to position 2645728 of chromosome 1 of the Refbeet 1.5 reference genome, and EPBV6296 is a T to C substitution corresponding to position 1117040 of chromosome 1 of the Refbeet 1.5 reference genome. In some aspects, the screening for the presence of QTL1 includes at least one of: PCR amplification of DNA with SEQ ID NO: 2 and SEQ ID NO: 3, PCR amplification of DNA with SEQ ID NO: 5 and SEQ ID NO: 6, PCR amplification of DNA with SEQ ID NO: 8 and SEQ ID NO: 9, PCR amplification of DNA with SEQ ID NO: 11 and SEQ ID NO: 12, and PCR amplification of DNA with SEQ ID NO: 14 and SEQ ID NO: 15. In some aspects, thescreening for the presence of QTL1 includes at least one of: PCR amplification of DNA with SEQ ID NO: 52 and SEQ ID NO: 54, PCR amplification of DNA with SEQ ID NO: 56 and SEQ ID NO: 57, and PCR amplification of DNA with SEQ ID NO: 58 and SEQ ID NO: 60.

[0024] In some aspects, the techniques described herein relate to a method of identifying a plant, plant part, or plant cell including a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 4 (QTL2), said method including the steps of: screening for the presence of QTL2, wherein QTL2 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV577030, PBV562771, PBV573138, PBV273480, and PBV82I05I, wherein: PBV577030 is an A to G substitution corresponding to position 5742753 of chromosome 4 of the Refbeet 1.5 reference genome, PBV562771 is a G to A substitution corresponding to position 9767085 of chromosome 4 of the Refbeet 1.5 reference genome, PBV573138 is an A to G substitution corresponding to position 10271308 of chromosome 4 of the Refbeet 1.5 reference genome, PBV273480 is a G to A substitution corresponding to position 46718199 of chromosome 4 of the Refbeet 1.5 reference genome, and PBV821051 is a G to A substitution corresponding to position 47855576 of chromosome 4 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL2. In some aspects, the screening for the presence of QTL2 includes at least one of: PCR amplification of DNA with SEQ ID NO: 17 and SEQ ID NO: 18, PCR amplification of DNA with SEQ ID NO: 20 and SEQ ID NO: 21, PCR amplification of DNA with SEQ ID NO: 23 and SEQ ID NO: 24, PCR amplification of DNA with SEQ ID NO: 26 and SEQ ID NO: 27, and PCR amplification of DNA with SEQ ID NO: 29 and SEQ ID NO: 30.

[0025] In some aspects, the techniques described herein relate to a method of identifying a plant, plant part, or plant cell including a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 8 (QTL3), said method including the steps of: screening for the presence of QTL3, wherein QTL3 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV148969, PBV331644, PBV882826, PBV374371, and PBV757436, wherein: PBV148969 is an A to G substitution corresponding to position 436005 of chromosome 8 of the Refbeet 1.5 reference genome, PBV331644 is a G to A substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, PBV882826 is an A to G substitution corresponding to position 7979633 of chromosome 8 of the Refbeet 1.5 reference genome, PBV374371 is a G to A substitution corresponding to position 8822544 of chromosome 8 ofthe Refbeet 1.5 reference genome, and PBV757436 is an A to C substitution corresponding to position 25201555 of chromosome 8 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL3. In some aspects, the screening for the presence of QTL3 further includes identifying a plant, plant part, or plant cell having at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV738292, PBV738293, and EPBV7349, wherein: PBV738292 is a G to an A substitution corresponding to position 35831 of chromosome 8 of the Refbeet 1.5 reference genome, PBV738293 is an A to G substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, and EPBV7349 is an A to C substitution corresponding to position 275340 of chromosome 8 of the Refbeet 1.5 reference genome. In some aspects, the screening for the presence of QTL3 includes at least one of: PCR amplification of DNA with SEQ ID NO: 32 and SEQ ID NO: 33, PCR amplification of DNA with SEQ ID NO: 35 and SEQ ID NO: 36, PCR amplification of DNA with SEQ ID NO: 38 and SEQ ID NO: 39, PCR amplification of DNA with SEQ ID NO: 41 and SEQ ID NO: 42, and PCR amplification of DNA with SEQ ID NO: 44 and SEQ ID NO: 45. In some aspects, the screening for the presence of QTL3 includes at least one of: PCR amplification of DNA with SEQ ID NO: 62 and SEQ ID NO: 63 PCR amplification of DNA with SEQ ID NO: 65 and SEQ ID NO: 66, and PCR amplification of DNA with SEQ ID NO: 67 and SEQ ID NO: 69.

[0026] In some aspects, the techniques described herein relate to a method of identifying a plant, plant part, or plant cell including a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 2 (QTL4), said method including the steps of: screening for the presence of QTL4, wherein QTL4 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821, wherein: GRKPBV98281 is a G to A substitution corresponding to position 8040503 of chromosome 2 of the Refbeet 1.5 reference genome, GRKPBV627372 is a C to an A substitution corresponding to position 9433027 of chromosome 2 of the Refbeet 1.5 reference genome, GRKPBV672273 is a G to an A substitution corresponding to position 12212298 of chromosome 2 of the Refbeet 1.5 reference genome, GRKPBV627178 is an A to C substitution corresponding to position 18410288 of chromosome 2 of the Refbeet 1.5 reference genome, GRKPBV 116271 is an A to C substitution corresponding to position 20007280 of chromosome 2 of the Refbeet 1.5 reference genome, and identifying a plant, plantpart, or plant cell having at least one of said marker loci linked to QTL4. In some aspects, the screening for the presence of QTL4 includes at least one of: PCR amplification of DNA with SEQ ID NO: 70 and SEQ ID NO: 72, PCR amplification of DNA with SEQ ID NO: 73 and SEQ ID NO: 75, PCR amplification of DNA with SEQ ID NO: 76 and SEQ ID NO: 78, PCR amplification of DNA with SEQ ID NO: 79 and SEQ ID NO: 81, PCR amplification of DNA with SEQ ID NO: 83 and SEQ ID NO: 84, and PCR amplification of DNA with SEQ ID NO: 85 and SEQ ID NO: 87.

[0027] In some aspects, the techniques described herein relate to a method of producing a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell having resistance to Beet Mild Yellowing Virus (BMYV), said method including the steps of: (a) providing a plant having resistance to Beet Mild Yellowing Virus (BMYV); (b) crossing the plant of (a) with another plant and harvesting the seed resulting from said cross; (c) growing the seed from step (b) to produce a progeny plant, and submitting the progeny plant to the method of identifying a plant including at least one of a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV); and (d) selecting a progeny plant which includes at least one of QTL1, QTL2, and QTL3. In some aspects, the selecting further includes selecting a progeny plant having QTL4. In some aspects, the selecting a progeny includes at least one of: PCR amplification of DNA with SEQ ID NO: 2 and SEQ ID NO: 3, PCR amplification of DNA with SEQ ID NO: 5 and SEQ ID NO: 6, PCR amplification of DNA with SEQ ID NO: 8 and SEQ ID NO: 9, PCR amplification of DNA with SEQ ID NO: 11 and SEQ ID NO: 12, and PCR amplification of DNA with SEQ ID NO: 14 and SEQ ID NO: 15. In some aspects, the selecting a progeny includes at least one of: PCR amplification of DNA with SEQ ID NO: 52 and SEQ ID NO: 54, PCR amplification of DNA with SEQ ID NO: 56 and SEQ ID NO: 57, and PCR amplification of DNA with SEQ ID NO: 58 and SEQ ID NO: 60. In some aspects, the selecting a progeny includes at least one of: PCR amplification of DNA with SEQ ID NO: 17 and SEQ ID NO: 18, PCR amplification of DNA with SEQ ID NO: 20 and SEQ ID NO: 21, PCR amplification of DNA with SEQ ID NO: 23 and SEQ ID NO: 24, PCR amplification of DNA with SEQ ID NO: 26 and SEQ ID NO: 27, and PCR amplification of DNA with SEQ ID NO: 29 and SEQ ID NO: 30. In some aspects, the selecting a progeny includes at least one of: PCR amplification of DNA with SEQ ID NO: 32 and SEQ ID NO: 33, PCR amplification of DNA with SEQ ID NO: 35 and SEQ ID NO: 36, PCR amplification of DNA with SEQ ID NO: 38 and SEQ ID NO: 39, PCR amplification of DNA with SEQ ID NO: 41 and SEQ ID NO: 42, and PCR amplification of DNA with SEQ ID NO: 44 and SEQ ID NO: 45. In some aspects, the selectinga progeny includes at least one of: PCR amplification of DNA with SEQ ID NO: 62 and SEQ ID NO: 63 PCR amplification of DNA with SEQ ID NO: 65 and SEQ ID NO: 66, and PCR amplification of DNA with SEQ ID NO: 67 and SEQ ID NO: 69. In some aspects, the selecting a progeny includes at least one of: PCR amplification of DNA with SEQ ID NO: 70 and SEQ ID NO: 72, PCR amplification of DNA with SEQ ID NO: 73 and SEQ ID NO: 75, PCR amplification of DNA with SEQ ID NO: 76 and SEQ ID NO: 78, PCR amplification of DNA with SEQ ID NO: 79 and SEQ ID NO: 81, PCR amplification of DNA with SEQ ID NO: 83 and SEQ ID NO: 84, and PCR amplification of DNA with SEQ ID NO: 85 and SEQ ID NO: 87. In some aspects, the method further includes (e) backcrossing said selected progeny plant to a parental line to produce a backcross progeny having two or more QTLs associated with resistance to Beet Mild Yellowing Virus. In some aspects, the method further includes (e) backcrossing said selected progeny plant to a parental line to produce backcross progeny having a desirable trait and resistance to Beet Mild Yellowing Virus. In some aspects, the method further includes introducing or introgressing a desirable trait introduced by a method selected from the group consisting of genetic transformation, genome editing, targeted mutagenesis, and induced random mutagenesis.

[0028] The present disclosure provides methods for reducing yield loss as a consequence of Beet Mild Yellowing Virus (BMYV) infection, the method comprising the steps of: (a) providing a seed for a plant having resistance to Beet Mild Yellowing Virus (BMYV), a plant identified by the method taught herein, or a plant produced by the method taught herein; and (b) planting said seed in areas which are prone to Beet Mild Yellowing Virus infection. In some aspects, the seed is planted in areas where the use of insecticides to control the vector for Beet Mild Yellowing Virus transmission is restricted, prohibited, or not desired.

[0029] The present disclosure provides methods for producing sugar, the method comprising the steps of: (a) growing the plant having resistance to Beet Mild Yellowing Virus (BMYV), a plant identified by the method taught herein, or a plant produced by the method taught herein, (b) harvesting the root / beet of said plant, and (c) extracting the sugar from said root / beet of (b). In some aspects, the growing is conducted without the use of insecticides and the sugar extracted from said root / beet is qualified for the organic market.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Various objects and advantages and a more complete understanding of the present disclosure are apparent and more readily appreciated by reference to the following Detailed Description and to the appended claims when taken in conjunction with the accompanyingDrawings. Referring now to the drawings, where like or similar elements are designated with identical reference numerals throughout the several views, and referring in particular to FIGs 1A- IF, they illustrate one embodiment of the present disclosure.

[0031] FIGs. 1A to IF illustrate the development of symptoms scored every 3rdweek during the growing season using a scale from 1-9, with 1 being the worst and 9 being the best. Examples of the scoring criteria are presented in FIG. 1A (score 3), FIG. IB (score 4), FIG. 1C (score 5), FIG. ID (score 6), FIG. IE (score 7), and FIG. IF (score 8).DETAILED DESCRIPTION

[0032] The following description includes information that may be useful in understanding the present disclosure. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed disclosures, or that any publication specifically or implicitly referenced is prior art.

[0033] Those skilled in the art can readily recognize that numerous variations and substitutions may be made in the disclosure, its use and its configuration to achieve substantially the same results as achieved by the embodiments described in the detailed description and examples.

[0034] The disclosure provides plants, plant parts, and plant cells that are resistant to yellowing viruses, and methods for producing plants exhibiting resistance to yellowing diseases caused by the pathogens such as Beet mild yellowing virus (BMYV), Beet yellows virus (BYV), Beet chlorosis virus (BChV), Beet mosaic virus (BtMV), and / or the Beet Western Yellows Virus (BWYV), thereby preventing yield loss and drag, and maintaining or even increasing yield for sugar production. Methods of breeding and selecting multiple virus resistant sugar beet lines are further provided, as well as plants, seeds, and commodity plant products of the same. Also disclosed herein are molecular markers that are linked to quantitative trait loci contributing to such yellowing virus resistance.

[0035] The inventors have identified QTL and markers associated with said QTL and have developed plants and methods of producing plants and commodity plant products having resistance to yellowing viruses, such as BMYV, BYV, BChV, BtMV, and BWYW.

[0036] Signs of viral infection include but are not limited to, (i) yellow and brown in the area of older leaves between the veins where small reddish brown spots often appear, (ii) thick, leathery, and brittle leaves, (iii) yellow etching of the heart leaves, (iv) sugar yield loss in root, and the like.

[0037] The disclosure provides methods and compositions that permit combination of multivirus resistance with the ability to produce a commercially acceptable sugar beet from a single line.

[0038] The ability to produce virus resistant plants can be hampered by problems associated with limited heritability of some resistance phenotypes. For instance, with regard to beet yellowing viruses, inconsistent disease reactions may occur in sequential tests on selected breeding lines.

[0039] The disclosure represents a significant advance in that it provides plants and methods of introgressing resistant traits into commercially acceptable genetic backgrounds that may be susceptible to the viruses or any susceptible plant line that is desired to acquire resistance to yellowing disease(s). In specific embodiments of the disclosure, a QTL conferring BMYV resistance is identified and defined by at least marker taught herein. In some embodiments, four Quantitative Trait Loci (QTL) are identified including QTL1 located on chromosome 1, QTL2 located on chromosome 4, QTL3 located on chromosome 8, and QTL4 located on chromosome 2, when using the Refbeet 1.5 reference genome (jbrowse.cebitec.uni- bielefeld.de / RefBeetl.5 / ?loc=Chrl%3A22456902..33687048&tracks=DNA&highlight=).

[0040] The first QTL (QTL1) identified herein that confers resistance to BMYV is located on chromosome 1 in the interval bounded by markers PBV504245, PBV125552, PBV291217, PBV369685, PBV261963, PBV757437, PBV638722, and EPBV6296.

[0041] The second QTL (QTL2) identified herein that confers resistance to BMYV is located on chromosome 4 in the interval bounded by markers PBV577030, PBV562771, PBV573138, PBV273480, and PBV821051.

[0042] The third QTL (QTL3) identified herein that confers resistance to BMYV is located on chromosome 8 in the interval bounded by markers PBV148969, PBV331644, PBV882826, PBV374371, PBV757436, PBV738292, PBV738293, and EPBV7349.

[0043] The fourth QTL (QTL4) identified herein that confers resistance to BMYV is located on chromosome 2 in the interval bounded by markers GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821.

[0044] Through use of the corresponding markers provided herein and / or other markers that may be linked thereto, one of skill in the art may use genetic markers to introgress and transfer virus resistance traits in commercially relevant varieties and beet lines.

[0045] In accordance with the disclosure, identified QTL may be introgressed into any different Beta vulgaris subsp. vulgaris (beet) genetic background. Thus, using the methods of the disclosure and starting from the genetic sources identified herein or available in the art, a beet plant of any genotype may be produced that further comprises the desired viral resistance, including BMYV, BYV and BChV. In addition, such plants may be prepared to comprise other desired traits, for example elite agronomic and root quality traits as desired.Definitions

[0046] The present disclosure may be understood more readily by reference to the following detailed description of the preferred embodiments of the disclosure and the examples included herein. Unless otherwise noted, the terms used herein are to be understood according to conventional usage by those of ordinary skill in the relevant art.

[0047] It is to be understood that as used in the specification and in the claims, “a” or “an” can mean one or more, depending upon the context in which it is used. Therefore, reference to “a nucleic acid” can mean that at least one nucleic acid can be utilized.

[0048] Furthermore, the terms “first”, “second”, “third” or “(i)”, “(ii)” , “(iii)” etc. are used herein for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. Such terms are interchangeable under appropriate circumstances and the embodiments of the disclosure described herein are capable of operation in other orders than the ones described herein.

[0049] The term "Beta vulgaris subsp. vulgaris plant" includes species used for feed and industrial purpose such as sugar beet or a fodder beet, and species used for food purpose such as red beet and mangold.

[0050] As used herein, "plant part” refers to cells, tissues or organs, seed pods, seeds, severed parts such as roots, leaves, flowers, pollen, root tips, anthers, pistils, embryos, ovules, cotyledons, hypocotyls, petiole, meristematic cells, shoots, gametophytes, sporophytes, and the like etc.

[0051] Progeny or descendants of the plants described herein which retain the distinguishing characteristics of the parents (especially the root dehiscence properties), such as seed obtained by selfing or crossing, e.g. hybrid seed (obtained by crossing two inbred parental lines), hybrid plants and plant parts derived therefrom are encompassed herein, unless otherwise indicated.

[0052] As used herein the term "progeny" or “descendent” is intended to mean the offspring or the first and all further descendants from a cross with a plant of the disclosure that showsthe resistance trait(s) and / or carries the genetic determinant(s) underlying the trait(s). Progeny of the disclosure comprises descendants of any cross with a plant of the disclosure that carries the genetic determinant(s) causing the resistance trait(s).

[0053] The term “Fl population” or “Fl generation” or “Fl” as used herein refers to the first filial generation produced by a cross. The term “F2 population” or “F2 generation” or “F2” as used herein refers to offspring produced by self-pollination of individuals of an Fl generation.

[0054] The term "variety" or "cultivar", which can be interchangeably used, refers to a plant genotype that is distinct, stable and uniform in its characteristics when propagated.

[0055] The term "Yellow Disease” as used herein refers to the disease caused by the pathogens Beet Mild Yellowing Virus (BMYV), Beet Yellows Virus (BYV) and / or Beet Chlorosis Virus (BChV), a common disease affecting plants of the Chenopodieae family that presents with symptoms including yellowing and loss of photosynthetic ability, which can eventually lead to severe sugar yield losses due to reduced root size and sugar content.

[0056] The term "BMYV resistance", “resistant to BMYV” or “resistant against BMYV” as used herein refers to resistance to one or more Beet Mild Yellowing Virus isolates Said resistance refers to a reduction of viral load and / or a plants ability to prevent and / or limit viral replication, resulting in a reducing in damage caused by BMYV infection compared to control plants not having resistance. Damage can be assessed as, for example, visual yellowing of the leaves, root size, sugar content and virus content. In particular, a reduction in damage is manifested in a reduced yield loss and / or loss off sugar productivity when plants are grown under disease pressure in the field, compared to control plants. Said resistance may also refer to plants that are completely resistant, i.e., plants on which no disease symptoms are found.

[0057] BMYV resistance can be assessed using a scale from 1 to 9, where 1 would indicate a completely dead plant, 2-3 severely yellowing plants, 4-6 moderately yellowing plants, 7-8 mildly yellowing plants, and 9 which would indicate a fully healthy and green plant. Based on the individual scoring values the disease index (DI) for each evaluation group (for example a plot) was calculated as follows: DI = (nl * l + n2 * 2 + n3 * 3 + n4 * 4 + n5 * 5 + n6 * 6 + n7 * 7 + n8 * 8 + n9 * 9) / N where nl to n9 is number of plants in the indicated class and N is the total number of plants tested.

[0058] It is understood that environmental conditions, such as location, weather conditions and disease pressure, as well as individual perception of the person assessing disease symptoms, can have an effect on the scoring of BMYV resistance. Hence, variation in these factors incomparative tests should be minimized. Any other resistance ratings known in the art can be applied in accordance with this disclosure to compare the plants of the disclosure with control plants.

[0059] As used herein, the term "quantitative trait locus" or “QTL” refers to a specific region on chromosomes, which harbors gene(s) controlling the trait. For the purposes of the present disclosure, the trait of particular interest is beet mild yellow virus (BMYV) resistance or resistance to BMYV. A quantitative trait is a trait that varies in degree and which can be attributed to polygenic effects, i.e. a product of two or more genes.

[0060] The term “locus” as used herein refers to a certain place or position in the genome, e.g. on a chromosome or chromosome arm, which comprises one or more genetic determinants, for example one or several genes, contributing to a trait, such as a resistance to a disease.

[0061] The term "marker" as used herein, refers to segment of nucleic acid that is inherited with a trait of interest. Thus, a molecular marker may be a short DNA sequence, such as a sequence surrounding a single base-pair change, i.e. a single nucleotide polymorphism or SNP, or a long DNA sequence, such as microsatellites or Simple Sequence Repeats (SSRs). The nature of the marker is dependent on the molecular analysis used and can be detected at the DNA, RNA or protein level

[0062] The term “monomorph” as used herein describes the situation when a bi-allelic marker detects only one of two possible alleles in a given plant population. The lack of nucleotide variation for this position precludes linkage between a marker specific for this nucleotide and any trait that segregates in this population.

[0063] The terms "genetically linked", "linked", "linked to" or "linkage", as used herein, refers to a measurable probability that genes or markers located on a given chromosome are being passed on together to individuals in the next generation. Thus, the term "linked" may refer to one or more genes or markers that are passed together with a gene with a probability greater than 0.5 (which is expected from independent assortment where markers / genes are located on different chromosomes). Because the proximity of two genes or markers on a chromosome is directly related to the probability that the genes or markers will be passed together to individuals in the next generation, the term genetically linked may also refer herein to one or more genes or markers that are located within about 50 centimorgan (cM) or less of one another on the same chromosome.

[0064] The term “interval marker” or “flanking marker” as used herein refers to a marker that defines one of the termini of an interval (and is included in that interval). It will be clear that any of such intervals may comprise further markers. Two or more interval markers may be located at the respective termini of the region of interest (e.g. a QTL). For example, one interval marker may be located at the 5 ’ end of the QTL and one interval marker may be located at the 3’ end of the QTL.

[0065] The term “interval” refers to a continuous linear span of chromosomal DNA with termini defined by map position and / or markers. A QTL positioned “between” two markers or “within an interval” is a QTL within a continuous linear span of chromosomal DNA that is flanked by two markers.

[0066] The “Refbeet 1.5 reference genome” as used herein refers to the assembled reference genome of the double-haploid KWS2320 line as published in Dohm JC, Minoche AE, Holtgrawe D, Capella-Gutierrez S, Zakrzewski F, Tafer H, Rupp O, Sorensen TR, Stracke R, Reinhardt R, Goesmann A, Kraft T, Schulz B, Stadler PF, Schmidt T, Gabaldon T, Lehrach H, Weisshaar B, Himmelbauer H. The genome of the recently domesticated crop plant sugar beet (Beta vulgaris). Nature. 2014 Jan 23;505(7484):546-9. doi: 10.1038 / naturel2817. Epub 2013 Dec 18. PMID: 24352233 and Minoche AE, Dohm JC, Schneider J, Holtgrawe D, Viehover P, Montfort M, Sorensen TR, Weisshaar B, Himmelbauer H. Exploiting single-molecule transcript sequencing for eukaryotic gene prediction. Genome Biol. 2015 Sep 2; 16( 1): 184. doi: 10.1186 / S13059-015-0729-7. PMID: 26328666; PMCID: PMC4556409. Electronically available on the worldwide web at: jbrowse.cebitec.uni- bielefeld.de / RefBeetl.5 / ?loc=Chrl%3A22466033..33696179&tracks=DNA&highlight=. Map positions in the reference genome refer to nucleotides of the respective chromosomes.

[0067] The term “contig” as used herein refers to a set of overlapping DNA segments that together represent a consensus region of DNA. In bottom-up sequencing projects, a contig refers to overlapping sequence data (reads); in top-down sequencing projects, contig refers to the overlapping clones that form a physical map of the genome that is used to guide sequencing and assembly. Contigs can thus refer both to overlapping DNA sequence and to overlapping physical segments (fragments) contained in clones depending on the context.

[0068] The term “scaffold” as, used herein, refers to overlapping DNA contigs that together represent a consensus region of DNA.

[0069] The phrase “isolating genomic DNA” as used herein refers to extraction of the genomic DNA from cells obtained from one or several organisms.

[0070] The term “KASP assay” as used herein describes an assay for detection of SNP markers. KASP genotyping assays are based on competitive allele-specific PCR and enable biallelic scoring of single nucleotide polymorphisms (SNPs) and insertions and deletions (Indels) at specific loci. For developing the KASP-assay 70-100 base pairs upstream and 70-100 base pairs downstream of the SNP are selected and two allele -specific forward primers and one allele specific reverse primer is designed. See e.g. Allen et al. 2011, Plant Biotechnology J. 9, 1086-1099, especially pl 097- 1098 for KASP assay method.

[0071] The term “SNP analysis” as used herein refers to the detection of one or more specific SNPs within the DNA extracted from a sample from an individual organism or a population of organisms using known methods. The analysis typically includes comparison between individuals or populations or comparison with a reference sequence.

[0072] The term “next-generation sequencing” or “NGS” refers to the high-throughput DNA sequencing using massively parallel sequencing of spatially separated, clonally amplified DNA templates or single DNA molecules using methods such as pyrosequencing or Illumina dye sequencing.

[0073] The term “Sanger sequencing”, also called “first-generation sequencing”, refers to a method of DNA sequencing based on the electrophoretic separation of chain-termination products produced in individual sequencing reactions.

[0074] The term “nuclease based detection” refers to a method of detection of DNA mismatches between two DNA fragments that differ in one nucleotide using a nuclease, e.g. Surveyor nuclease, that specifically detects mismatches in the DNA and then cleaves the DNA at the site of the mismatch.

[0075] The term “DNA chip technology”, “DNA microchip”, “biochip” or “DNA microarray” refers to a collection of microscopic DNA molecules attached to a solid surface or beads. DNA chip technology can for example be used for SNP detection, gene expression profiling or chromatin immunoprecipitation.

[0076] The term “zygosity status” as used herein refers to the type and number of allele present at a specific locus in the genome on a pair of homologous chromosomes. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different,the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous.

[0077] The terms “sequence Identity”, “% sequence identity”, “% identity”, “% identical” or “sequence alignment” are used interchangeably herein and refer to the comparison of a first nucleic acid sequence to a second nucleic acid sequence, or a comparison of a first amino acid sequence to a second amino acid sequence and is calculated as a percentage based on the comparison. The result of this calculation can be described as “percent identical” or “percent ID.” A sequence identity may be determined by a program, which produces an alignment, and calculates identity counting both mismatches at a single position and gaps at a single position as non-identical positions in final sequence identity calculation. The sequence identity is determined over the entire length of the first and second nucleic acid sequence. When percentage of sequence identity is used in reference to proteins it is recognized that residue positions which are not identical often differ by conservative amino acid substitutions, where amino acid residues are substituted for other amino acid residues with similar chemical properties (e.g., charge or hydrophobicity) and therefore do not change the functional properties of the molecule. Where sequences differ in conservative substitutions, the percent sequence identity may be adjusted upwards to correct for the conservative nature of the substitution. Sequences which differ by such conservative substitutions are said to have "sequence similarity" or "similarity." Means for making this adjustment are well-known to those of skill in the art. Typically this involves scoring a conservative substitution as a partial rather than a full mismatch, thereby increasing the percentage sequence identity. Thus, for example, where an identical amino acid is given a score of 1 and a non-conservative substitution is given a score of zero, a conservative substitution is given a score between zero and 1. The scoring of conservative substitutions is calculated, e.g., according to the algorithm of Meyers and Miller, Computer Applic. Biol. Sci., 4: 11-17 (1988). The comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm. An example of a local alignment algorithm utilized for the comparison of sequences is the NCBI Basic Local Alignment Search Tool (BLAST®) (Altschul et al. 1990 J. Mol. Biol. 215: 403-10), which is available from several sources, including the National Center for Biotechnology Information (NCBI, Bethesda, Md.) and on the Internet, for use in connection with the sequence analysis programs blastp, blastn, blastx, tblastn and tblastx. It can be accessed on the internet via the National Library of Medicine (NLM)'s world-wide-web URL. A description of how to determine sequence identity using thisprogram is available at the NLM's website on BLAST tutorial. Another example of a mathematical algorithm utilized for the global comparison of sequences is the Clustal W and Clustal X (Larkin et al. 2007 Bioinformatics, 23, 2947-294, Clustal W and Clustal X version 2.0) as well as Clustal omega. Unless otherwise stated, references to sequence identity used herein refer to the NCBI Basic Local Alignment Search Tool (BLAST®).

[0078] The term “conferring resistance” or “confers resistance” as used herein refers to a gene, nucleic acid, allele, marker, SNP, or coding variant resulting an increased resistance to a disease or pathogen.

[0079] The terms "transgene" as used herein refers to at least one nucleic acid sequence that is taken from the genome of one organism, or produced synthetically, and which is then introduced into a host cell or organism or tissue of interest and which is subsequently integrated into the host's genome by means of transformation or transfection approaches. The term “transgenic” refers to an organism carrying a transgene, and the term “transgenesis” refers to the processes or methods of producing a transgenic organism.

[0080] The term "genome editing” as used herein refers to strategies and techniques for the modification of any genetic information or genome by means of or involving a double stranded DNA break inducing enzyme or single-stranded DNA or RNA break inducing enzyme. As such, the terms comprise gene editing, but also the editing of regions other than gene encoding regions of a genome, such as intronic sequences, non-coding RNAs, miRNAs, sequences of regulatory elements like promoter, terminator, transcription activator binding sites, cis or trans acting elements. Additionally, the terms may comprise base editing for targeted replacement of single nucleobases. It can further comprise the editing of the nuclear genome as well as other genetic information, i.e. mitochondrial genome, chloroplast genome or an artificial genome or chromosome as well as miRNA, pre-mRNA or mRNA.

[0081] The term “targeted mutagenesis” or “site-directed mutagenesis” as used herein refers to a method of making targeted, specific changes to a DNA sequence using methods of molecular biology. Targeted mutagenesis includes, but is not limited to, CRISPR, TILLING, and TALEN methods.

[0082] The term “non-targeted mutagenesis” or “random mutagenesis” refers to a method wherein a mutagen or molecular biology method is used to introduce random changes into DNA. This can be achieved, for example, using UV radiation, mutagenic chemicals such asethyl methane sulfonate (EMS) or nitrous acid, error prone PCR, DNA shuffling, insertion mutagenesis kits, or mutator strains with impaired DNA repair machinery.

[0083] The term “harvested part” as used herein refers to any picked or collected part of a crop plant.

[0084] The term “feed product” refers to any agricultural foodstuff made from plant material used to feed domesticated livestock, also called “fodder” or “provender”.

[0085] The term “sugar” as used herein refers to a saccharide that is a product obtained from a sugar beet that can be used as a food product or in the production of biofuels.

[0086] The term “derived products” as used herein refers to any final product or by-product obtained from a beet plant.

[0087] The term "resistance" or “resistant” means the ability of a plant variety to restrict the infection, growth and / or development of a specified pest or pathogen (i.e., the host’s ability to limit pathogen multiplication) and the damage they cause when compared to susceptible plant varieties under similar environmental conditions and pest or pathogen pressure. Resistant varieties may exhibit some disease symptoms or damage under heavy pest or pathogen pressure. Following an infection by the virus, the viral load in the resistant variety (as measured for example in an ELISA assay or qPCR) is reduced in comparison to the susceptible variety.

[0088] The term “tolerance” or “tolerant” means the host’s ability to reduce the effect of infection on its fitness regardless of the level of pathogen multiplication. The term is used herein to indicate a phenotype of a plant wherein disease symptoms remain reduced or absent upon exposure of said plant to an infective dosage of virus, whereby the presence of a systemic or local infection, virus multiplication, the presence of viral genomic sequences in cells of said plant and / or genomic integration thereof can be established. Tolerant plants are therefore carriers of the virus with less symptoms. Usually, viral sequences may be present or even multiply in plants without causing disease symptoms. Following an infection by the virus, the viral load in a tolerant variety (as measured for example in an ELISA assay or qPCR) is not substantially reduced. Also see: A Dictionary of Plant Pathology. By P. Holliday. Cambridge: Cambridge University Press (1992), pp. 369, ISBN 0-521-42475-5; Pagan I, Garcia-Arenal F. Tolerance to Plant Pathogens: Theory and Experimental Evidence. Int J Mol Sci. 2018 Mar 1 l;19(3):8I0).

[0089] As used herein, the term “susceptibility” or “susceptible” is used herein to refer to a plant which is not resistant. The term “susceptible” is therefore equivalent to “non-resistant”.

[0090] As used herein, the term "trait" refers to a phenotype of interest.

[0091] The term “introgression” as used herein refers to the incorporation of genetic material, such as alleles or genes, from one plant (e.g., a species or variety) into the gene pool of another.

[0092] As used herein, the term "human-induced random mutagenesis" is intended to be understood in a conventional manner, i.e., to indicate an introduction of one or more mutations at random positions of the target sequence (i.e., as opposed to site-specific mutagenesis). The random mutations are typically introduced by exposing plant, plant part, or plant cell to a mutagen and then screening for the presence of variants. Mutagens for random mutagenesis are well known in the art, and include, for example, physical or chemical mutagenizing agent.

[0093] As used herein, the term “mutagen" refers to a compound or process that results in the introduction of mutations in the plant genome. Examples of mutagens include biological mutagens such as transposons, chemical mutagens such as N-nitroso-N-ethylurea, N-nitroso- N-methylurea, ethylmethane sulfonate (EMS), sodium azide, radiation, or other mutagens. The radiation may be ultra-violet radiation, X-ray radiation, gamma radiation, alpha radiation, beta radiation, ion beams such as 4He<2+> and H<+>, etc.

[0094] In an embodiment, the additional trait or plant comprising said additional trait is not exclusively obtained by an essentially biological process. The term "exclusively" in this context means that the method of establishing the additional trait and / or the plant comprising said additional trait is not entirely based on the crossing of whole genomes (i.e., an essentially biological process), but that the process contains - within the steps of sexually crossing and selecting - an additional step of a technical nature, which step by itself introduces a trait into the genome or modifies a trait in the genome of the plant produced, so that the introduction or modification of that trait is not the result of the mixing of the genes of the plants chosen for sexual crossing.

[0095] A trait or plant “established by a method such as genetic transformation, genome editing, targeted mutagenesis, and induced random mutagenesis” means a process which by itself introduces a trait into the genome or modifies a trait in the genome of the plant produced, so that the introduction or modification of that trait is not the result of the mixing of the genes of the plants chosen for sexual crossing.

[0096] Transformation of plant cells refers to process by which DNA is integrated into the genome of a plant cell. The integration may be transient or stable. “Stably” refers to the permanent, or non-transient retention and / or expression of a polynucleotide in and by a cellgenome. Thus, a stably integrated polynucleotide is one that is a fixture within a transformed cell genome and can be replicated and propagated through successive progeny of the cell or resultant transformed plant. Transformation may occur under natural or artificial conditions using various methods well known in the art. Transformation may rely on any known method for the insertion of nucleic acid sequences into a prokaryotic or eukaryotic host cell, including Agrobacterium-mediated transformation protocols, viral infection, whiskers, electroporation, heat shock, lipofection, polyethylene glycol treatment, micro-injection, and particle bombardment.

[0097] Transgenic plant refers to genetically modified plant which contains at least one transgene.Beta genus

[0098] Genus “Beta” belongs to the foxtail family (Amaranthaceae). The best known member is the common beet, Beta vulgaris, but several other species are recognized. These plants include plants of the species Beta macrocarpa, Beta vulgaris, Beta lomatogona, Beta macrorhiza, Beta coroffiflora, Beta trigyna and Beta nana. A plant of the species Beta vulgaris is, in particular, a plant of the subspecies Beta vulgaris subsp. vulgaris. These include, for example, Beta vulgaris subsp. vulgaris var. altissima, Beta vulgaris ssp. vulgaris var. vulgaris (chard), Beta vulgaris ssp. vulgaris var. conditiva, Beta vulgaris ssp. vulgaris var. crassa / alba.Beet, Beta vulgaris

[0099] Beta vulgaris is a plant which is included in the subfamily Betoideae of the family Amaranthaceae. It is the economically most important crop of the large order Caryophyllales. It has several cultivar groups: the sugar beet, of greatest importance to produce table sugar; the root vegetable known as the beetroot or garden beet; the leaf vegetable known as chard or spinach beet; and mangelwurzel, which is a fodder crop. Three subspecies are typically recognized, but all cultivated beets fall into the subspecies Beta vulgaris subsp. vulgaris. The wild ancestor of the cultivated beets is the sea beet (Beta vulgaris subsp. maritima), and its Center of Origin lies in the Mediterranean region.

[0100] The beetroot is the taproot portion of a beet plant, usually known in Canada and the USA as beets, while the vegetable is referred to as beetroot in British English. It is also known as the table beet, garden beet, red beet, dinner beet or golden beet. It is one of several cultivargroups of Beta vulgaris grown for their edible taproots and leaves (called beet greens). These have been classified as B. vulgaris subsp. vulgaris ‘Conditiva’ Group.

[0101] Beta vulgaris (beet) is an herbaceous biennial or, rarely, perennial plant. Cultivated forms of beets are mostly biennial. The plant is usually erected with a long main root and a rosette of leaves growing on stems. The roots of cultivated forms are dark red, white, or yellow and moderately to strongly swollen and fleshy (subsp. vulgaris),' or brown, fibrous, sometimes swollen and woody in the wild subspecies. The stems grow erect or, in the wild forms, often procumbent; they are simple or branched in the upper part and their surface is ribbed and striate. The basal leaves have a long petiole (which may be thickened and red, white, or yellow in some cultivars). The simple leaf blade is oblanceolate to heart-shaped, dark green to dark red, slightly fleshy, usually with a prominent midrib, with entire or undulate margin, 5-20 cm long on wild plants (often much larger in cultivated plants about 20-40cm). The upper leaves are smaller, their blades are rhombic to narrowly lanceolate. (Shultz, L. M 2003 Beta vulgaris. In: Flora of North America Editorial Committee (eds.): Flora of North America North of Mexico, Volume 4: “Magnoliophyta: Caryophyllidae”, part 1., Oxford University Press, New York, p. 266-267; Zhu G et al 2003 Beta vulgaris In: Zhengyi, W., Raven, P. H., & Hong, D. (eds.): Flora of China. Volume 5: Ulmaceae through Basellaceae. Science Press / Missouri Botanical Garden Press, Beijing / St. Louis, p. 354.)

[0102] The plant produces sessile green flowers and can reach 1-2 m in height. Beets are usually grown as annual plants and harvested after one growing season. The flowers are produced in dense spike-like, basally interrupted inflorescences. Very small flowers sit in one- to three- (rarely eight-) flowered glomerules in the axils of short bracts or in the upper half of the inflorescence without bracts. The hermaphrodite flowers are urn-shaped, green or tinged reddish, and consist of five basally connate perianth segments (tepals), five stamens, and a semi -inferior ovary with two-three stigmas. The perianths of neighboring flowers are often fused. Flowers are wind-pollinated or insect-pollinated, the former method being more important. (Flores Olvera H. et al. 2008 “Floral and Inflorescence Morphology and Ontogeny in .Beta vulgaris, with Special Emphasis on the Ovary Position”. Annals of Botany. 102 (4): 643-651; Free, J. B. et al. 1975 “Insect pollination of sugar-beet (Beta vulgaris) seed crops”. Annals of Applied Biology. 81 (2): 127-134).

[0103] In fruit, the glomerules of flowers form connate hard clusters. The fruit (utricle) is enclosed by the leathery and incurved perianth, and is immersed in the swollen, hardened perianth base. The horizontal seed is lenticular, 2-3 mm, with a red-brown, shiny seed coat.The seed contains an annular embryo and copious perisperm (feeding tissue). (Shultz, L. M 2003 Beta vulgaris. In: Flora of North America Editorial Committee (eds.): Flora of North America North of Mexico, Volume 4: “Magnoliophyta: Caryophyllidae”, part 1., Oxford University Press, New York, p. 266-267; Zhu Get al 2003 Beta vulgaris In: Zhengyi, W., Raven, P. H., & Hong, D. (eds.): Flora of China. Volume 5: Ulmaceae through Basellaceae. Science Press / Missouri Botanical Garden Press, Beijing / St. Louis, p. 354.)

[0104] There are 18 chromosomes found in 2 sets, which makes beets diploid (2n=18).Beet Yellowing Disease

[0105] The beet yellowing disease appears in circles in the fields, in the form of lightening and then yellowing of the lamina between the veins of leaves. The leaves thicken and become brittle. These symptoms first form limited areas of infection in the fields and then rapidly spread throughout the entire field. Yellowing viruses can cause yield losses of 50 % when it infects the crop in early June. Infection reduces the photosynthetic area of leaves reducing yield and sugar content.The main vector aphids of yellowing are the green peach aphid (Myzus persicae) and the black bean aphid (Aphis fabae). Myzus persicae, the green peach aphid, is the main vector for all aphid-transmitted virus species in sugar beet fields (Limburg, D.et al., (1997) Characteristics of beet yellows closterovirus transmission to sugar beets by Aphis fabae. Phytopathology, 87, 766-771; Schliephake, E., et al., (2000) Investigations on the vector transmission of the Beet mild yellowing virus (BMYV) and the Turnip yellows virus (TuYV). Journal of Plant Diseases and Protection, 81-87; Kozlowska-Makulska, A., et al. (2009) Aphid transmissibility of different European beet polerovirus isolates. European Journal of Plant Pathology, 125, 337- 341). The beet is infected in spring by these aphids that are carriers of the virus. They in turn have contracted this virus by eating other infected beets or other host plants (winter spinach and a lot of pothead plants). In the summer, the aphids multiply and transmit the virus to the entire field. A mild fall and winter will encourage the emergence of a significant population early on. A dry and warm spring will provide a significant population of lice during the summer.The disease is widespread across all sugar beet regions of Europe. If it strikes early in the season, it can be the cause of significant yield loss, reduced sugar content and lower industrial quality (R. Hossain, et al., New insights into virus yellows distribution in Europe and effects of beet yellows virus, beet mild yellowing virus, and beet chlorosis virus on sugar beet yield following field inoculation. Plant Pathology. 70(3):584-593, 29 October 2020).

[0106] There are various types of yellowing, caused by several viruses. The most important are: The BYV (Beet Yellows Virus) belonging to the genus Closterovirus (characterized by a lemon-yellow coloration, which can subsequently cause small reddish necroses), the Beet Mild Yellowing Virus (BMYV), the Beet Western Yellows Virus (BWYV) and the Beet Chlorosis Virus (BChV). BMYV, BChV, and BWYV are characterized by a more orange coloration, often followed by cryptogamic infestation (e.g. Altemaria) and premature leaf necrosis (see for example bisz.suedzucker.de / pflanzenschutz / blatt-krankheiten / viroese-vergilbung / available on the worldwide web).Beet yellows virus belongs to the genus Closterovirus in the family Closteroviridae . Infections with BYV lead to yellowish discoloration of the older leaves and subsequently reddish necrosis may occur (de Koeijer and van der Werf, 1999 Effects of Beet yellows virus and Beet mild yellowing virus on leaf area dynamics of sugar beet (Beta vulgaris L.). Field Crops Research, 61, 163-177).). BYV can be transmitted by more than 20 different aphid species in a semipersistent mode of transmission. In addition to M. persicae, Aphis fahae can contribute to virus transmission (Limburg et al., 1997). BYV virions move via the phloem but can also colonize mesophyll and epidermal cells and have been detected in plasmodesmata that connect the different cell types of the phloem (Dolja, V.V. (2003) Beet yellows virus', the importance of being different. Molecular Plant Pathology, 4, 91-98; Dolja, V.V. & Koonin, E.V. (2013) The closterovirus- derived gene expression and RNA interference vectors as tools for research and plant biotechnology. Frontiers in Microbiology, 4, 83).Beet mild yellowing virus, Beet western yellows virus, and Beet chlorosis virus belong to the genus Polerovirus in the family Luteoviridae . In Beta species, the viruses induce yellow to orange leaf discoloration, which may cause premature foliage death (Lewellen, R.T., et al. (1999) Reaction of sugar beet breeding lines and hybrids to beet chlorosis luteovirus. Journal of Sugar Beet Research, 36, 76). Poleroviruses are persistently transmitted by their aphid vectors (Gray & Gildow, 2003 Luteovirus-aphid interactions. Annual Review of Phytopathology, 41, 539-566). Studies have shown that BMYV and BChV are efficiently transmitted by M. persicae (100%) and Macrosiphum euphorbiae (83%— 98%) (Kozlowska- Makulska et al., 2009).Beet mosaic virus belongs to the genus Potyvirus int the family Potyviridae. Symptoms of BtMV infection initially appear as yellowish speckles before the typical mosaic-like structures appear. In addition, the leaves are often malformed (Dunning & Byford, 1982 Pests, Diseasesand Disorders of the Sugar Beet. Deleplanque: Brooms Bam Experimental Station). BtMV is transmitted via a nonpersistent mechanism (Gallet et al., 2018 Vector-transmission of plant viruses and constraints imposed by virus-vector interactions. Current Opinion in Virology, 33, 144-150). The main vectors for the transmission of BtMV in the field are M. persicae and A. fahae (Dusi & Peters, 1999 Beet mosaic virus', its vector and host relationships. Journal of Phytopathology, 147, 293-298). However, the vims can also be transmitted by many other species such as Myzus ascalonicus (Semal, J. (1956) Transmission of Beet mosaic virus from Stellaria media and Capsella hursa-pastoris by Myzus ascalonicus Doncaster. Nature, 178, 501-502), M. euphorhiae, Acyrthosiphon pisum, Metopolophium dirhodum, and Rhopalosiphum padi (Dusi & Peters, 1999). In some embodiments, the vector for BMYV vims is Myzus persicae.Control of Beet Yellowing Disease

[0107] Thus far, BYV has primarily been controlled by controlling the insect vector through spay of insecticides. However, climate change with warmer winters and the regulatory restriction on certain insecticides (especially neonicotinoid class) in the EU resulted in a significant increase of the problem. With the ban of neonicotinoids as insecticides in many countries (especially EU in 2019) the insecticides available to control the insect vectors have become very limited (currently only Tefluthrin products such as Force 20 CS). In can be expected that the regulatory scmtiny against insecticides will increase and expand. In addition, treatment with insecticides is not compatible with organic agriculture and / or the “Bio” label of resulting products. In consequence there is a high need for developing sugar beet varieties which are tole resistant against yellowing vimses. (cropscience.bayer.co.uk / threats / diseases / sugar-beet-diseases / vims-yellows-beet / )

[0108] There are currently no varieties with a resistance against any yellowing vims.

[0109] Instead, Mamscha KWS has shown tolerance to BMYV. It is reported that under BMYV infection Mamscha KWS shows losses of 4% but still yields over 15t / ha more than the mean of KWS control varieties. Under BYV infection Mamscha KWS can show losses of 37% in yield, however it still yields 1 Ot / ha more than the mean of KW S UK non-tolerant commercial varieties under BYV infection. Mamscha KWS exhibits lower symptom expression - a greener canopy. However, in the absence of vims infection they do not reach the performance of non- tolerant varieties.Genetic mapping of virus yellows resistance

[0110] The genetic determinants for the trait was initially mapped using a backcrossed population in where the resistant germplasm was backcrossed with three different susceptible genotypes. From each cross, more than 180 BC1 -plants were analyzed using 95 AFLP -markers and phenotyped for BMYV resistance. The linkage between genetic region and trait was evaluated phenotypically in more than 2000 thousand individual plants to ensure data of required quality. The genetic determinants were then identified using statistical methods (t-test and power analysis). Fine mapping was then carried out by selecting one of the previously mentioned backcrosses and creating four different F2 populations by selfing four BC1 -plants. From these BCISl-population, four individual plants were selected based on heterozygosity in the identified regions (one for chromosome 1, two for chromosome 4 and one for chromosome 8). From these populations, 12 individuals were selected and analyzed using 48 specially designed TaqMan markers covering the identified regions on chromosomes 1, 4 and 8. The genetic determinants for the trait are composed of three regions located on chromosomes 1, 4 and 8 with an average size of 26.6 cM stemming from three mapping populations. Based on this information, flanking KASP markers for the trait were then developed to allow for the identification of crossovers close to the region of interest. Additional markers between the two flanking markers were also developed to ensure correct introgression in later steps.[oni] To further improve the mapping of the genetic determinants an additional mapping population was established by crossing the resistant germplasm with an unrelated susceptible germplasm to form an Fl -population. From this initial cross, using a single-seed lineage method, an F2 population consisting of more than 1000 individuals in which all mapped genetic determinants were segregating was established. From this populations, more than 450 individuals were selected and selfed to create an F2S1 population. The individuals in this population was then further selfed to create an F2S2 population. Each parental plant in the F2S1 generation was genotyped using more than 21 000 SNP-markers. The genetic determinants were then identified using statistical genetic analysis tools for inheritance based trait mapping as well as multiple marker association models. The position and extent of the genetic determiats were determined using both maximum likelihood single point estimation (MLSPE) as well as through 95% Bayesian interval mapping. A total of 27 trait specific markers were developed.

[0112] Four regions of the genetic determinants described above correspond to Quantitative Trait Loci (QTL) comprising QTL1, QTL2, QTL3, and QTL4.

[0113] QTL1 is located on chromosome 1 and genetically linked to at least one marker loci as follows: PBV504245 is a single nucleotide polymorphism (SNP) corresponding to position 1050427 of chromosome 1 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or C, with G being the nucleotide for the resistant line; PBV125552 is a SNP corresponding to position 3069972 of chromosome 1 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or G, with A being the nucleotide for the resistant line; PBV291217 is a SNP corresponding to position 4315236 of chromosome 1 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or G, with A being the nucleotide for the resistant line; PBV369685 is a SNP corresponding to position 4330737 of chromosome 1 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or A, with G being the nucleotide for the resistant line; aPBV261963 is a SNP corresponding to position 4356001 of chromosome 1 of the Refbeet 1.5 reference genome, wherein said nucleotide is T or A, with T being the nucleotide for the resistant line; PBV757437 is a SNP corresponding to position 17043 of chromosome 1 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or A, with A being the nucleotide for the resistant line; PBV638722 is a SNP corresponding to position 2645728 of chromosome 1 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or G, with G being the nucleotide for the resistant line; and EPBV6296 is a SNP corresponding to position 1117040 of chromosome 1 of the Refbeet 1.5 reference genome, wherein said nucleotide is T or C, with C being the nucleotide for the resistant line.

[0114] QTL2 is located on chromosome 4 and genetically linked to at least one marker loci as follows: selected from the group consisting of PBV577030 is a SNP corresponding to position 5742753 of chromosome 4 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or A, with G being the nucleotide for the resistant line; PBV562771 is a SNP corresponding to position 9767085 of chromosome 4 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or G, with A being the nucleotide for the resistant line; PBV573138 is a SNP corresponding to position 10271308 of chromosome 4 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or A, with G being the nucleotide for the resistant line; PBV273480 is a SNP corresponding to position 46718199 of chromosome 4 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or G, with A being the nucleotide for the resistant line, and PBV821051 is a SNP corresponding to position 47855576 of chromosome 4 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or G, with A being the nucleotide for the resistant line.

[0115] QTL3 is located on chromosome 8 and genetically linked to at least one marker loci as follows: PBV148969 is a SNP corresponding to position 436005 of chromosome 8 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or A, with G being the nucleotide for the resistant line; PBV331644 is a SNP corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or G, with A being the nucleotide for the resistant line; PBV882826 is a SNP corresponding to position 7979633 of chromosome 8 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or A, with G being the nucleotide for the resistant line; PBV374371 is a SNP corresponding to position 8822544 of chromosome 8 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or G, with A being the nucleotide for the resistant line; PBV757436 is a SNP corresponding to position 25201555 of chromosome 8 of the Refbeet 1.5 reference genome, wherein said nucleotide is C or A, with C being the nucleotide for the resistant line; PBV738292 is a SNP corresponding to position 35831 of chromosome 8 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or A, with A being the nucleotide for the resistant line; PBV738293 is a SNP corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or G, with G being the nucleotide for the resistant line; and EPBV7349 is a SNP corresponding to position 275340 of chromosome 8 of the Refbeet 1.5 reference genome, wherein said nucleotide is A or C, with C being the nucleotide for the resistant line.

[0116] QTL4 is located on chromosome 2 and is genetically linked to at least one marker loci as follows: GRKPBV98281 is a SNP corresponding to position 8040503 of chromosome 2 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or A, with A being the nucleotide for the resistant line; GRKPBV627372 is a SNP corresponding to position 9433027 of chromosome 2 of the Refbeet 1.5 reference genome, wherein said nucleotide is C or A, with A being the nucleotide for the resistant line; GRKPBV672273 is a SNP corresponding to position 12212298 of chromosome 2 of the Refbeet 1.5 reference genome, wherein said nucleotide is G or A, with A being the nucleotide for the resistant line; GRKPBV627178 is a SNP corresponding to position 18410288 of chromosome 2 of the Refbeet 1.5 reference genome, wherein said nucleotide is an A or C, with C being the nucleotide for the resistant line; GRKPBV116271 is a SNP corresponding to position 20007280 of chromosome 2 of the Refbeet 1.5 reference genome, wherein said nucleotide is an A or C, with C being the nucleotide for the resistant line; and EPBV8821 is a SNP corresponding to position 10704110 ofchromosome 2 of the Refbeet 1.5 reference genome, wherein said nucleotide is a G or A, with A being the nucleotide for the resistant line.

[0117] QTL1, QTL2, QTL 3, and QTL 4 are obtainable from a Beta plant, such as Beta vulgaris subsp. vulgaris line 21000003-71, representative seed of which has been deposited under Deposit Number NCIMB 44107.Yellowing Disease Resistant Plants of the genus Beta

[0118] The present invention provides plants, plant parts, and plant cells of the genus Beta resistant to beet yellowing disease(s) caused by Beet yellowing virus(s). As described above, the inventors identified resistant germplasm and mapped the resistant trait to four quantitative trait loci, QTL1, QTL2, QTL3, and QTL4. They further identified multiple markers for each QTL and have crossed the BMYV resistance trait into Beta genetic backgrounds, thus obtaining resistant Beta plants, especially, sugar beet (Beta vulgaris subsp. vulgaris) plant.

[0119] In one embodiment, the present disclosure provides a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell resistant to BMYV, wherein said plant, plant part, or plant cell comprises at least one of QTL1, QTL2, QTL3, and QTL 4.

[0120] In some embodiments, the QTL1 on chromosome 1 is genetically linked to at least one of markers PBV504245, PBV125552, PBV291217, PBV369685, PBV261963, PBV757437, PBV638722, and EPBV6296.

[0121] In some embodiments, the QTL2 on chromosome 4 is genetically linked to at least one of markers PBV577030, PBV562771, PBV573138, PBV273480, and PBV82I05I.

[0122] In some embodiments, the QTL3 on chromosome 8 is genetically linked to at least one of markers PBV148969, PBV331644, PBV882826, PBV374371, PBV757436, PBV738292, PBV738293, and EPBV7349.

[0123] In some embodiments, the QTL4 on chromosome 2 is genetically linked to at least one of markers GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821.

[0124] In some embodiments, said QTLs conferring resistance to BMYV are located at less than 30 cM, less than 25 cM, less than 20 cM, less than 15 cM, less than 10 cM, less than 5 cM, less than 1 cM, or less than 0.5cM from said markers.

[0125] In some embodiments, said QTLs conferring resistance to BMYV are located from about 20 cM to about 30 cM of said markers.

[0126] In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell heterozygous for QTL1, QTL2, QTL3 and QTL4. In some embodiments, the disclosure relates to a. Beta vulgaris subsp. vulgaris plant, plant part, or plant cell homozygous for QTL1, QTL2, QTL3, and QTL4.

[0127] In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell heterozygous for at least one of QTL1, QTL2, QTL3, and QTL4. In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell homozygous for at least one of QTL1, QTL2, QTL3, and QTL4.

[0128] In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell heterozygous for QTL1 and homozygous for at least one of QTL2, QTL3, and QTL4. In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell heterozygous for QTL2 and homozygous for at least one of QTL1, QTL3, and QTL4. In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell heterozygous for QTL3 and homozygous for at least one of QTL1, QTL2, and QTL4. In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell heterozygous for QTL4 and homozygous for at least one of QTL1, QTL2, and QTL3.

[0129] In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell homozygous for QTL1 and heterozygous for at least one of QTL2, QTL3, and QTL4. In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell homozygous for QTL2 and heterozygous for at least one of QTL1, QTL3, and QTL4. In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell homozygous for QTL3 and heterozygous for at least one of QTL1, QTL2, and QTL4. In some embodiments, the disclosure relates to a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell homozygous for QTL4 and heterozygous for at least one of QTL1, QTL2, and QTL3.

[0130] In another embodiment, the development of plants resistant against Beet Yellows Virus is taught herein. The present disclosure provides a genetic resistance solution to the problem. The resistance works primarily against Beet Mild Yellow Virus and partially for others some Yellow Viruses. It prevents yield loss from viral infection. The trait is differentiated from the Maruscha and Novalina varieties in that the resistance effectively and significantly lowers theviral load as demonstrated by ELISA assay. This results in a strong suppression of the visible symptoms and protects yield.

[0131] The trait is dominant (or at least partially dominant) and can confer resistance in heterozygous or homozygous form. This enables creating multiple hybrids without major efforts in introgression.

[0132] The disclosure is applicable to sugar beet, fodder beet, but potentially also to vegetable beet crops (red beet etc.). It is especially beneficial for varieties which are targeting the bio- organic sector, where chemical insecticides cannot be used.

[0133] In some embodiments, seeds obtained from the yellowing -virus resistant beet plants are planted in areas where the use of insecticides to control the vector for BMYV transmission is restricted, prohibited, or not desired. In some embodiments, plants germinated from the seeds are grown under the controlled conditions or environments without the use of insecticides. In further embodiments, the plants produce roots and / or beets, which can be used to produce sugar that is qualified for the organic market.

[0134] The term “organic” or “organically grown" refers to plant or food grown and processed using no synthetic fertilizers, insecticides or pesticides. Pesticides derived from natural sources (such as biological pesticides) may be used in producing organically grown plant or food. As a result, commodity products from organic or organically grown plants is free of the effect of synthetic fertilizers, pesticides, or insecticides, fungicides, nematicides, etc. In some embodiments, the pesticides used to control the disease (or aphids as virus vectors) are not allowed in organic farming. In further embodiments, organic cultivation of sugar beet in virus yellows infested regions will require a strong genetic resistance as the currently used pesticides are not allowed or applied in organic farming.

[0135] In some embodiments, a seed of the yellowing virus resistant plant is technically treated, whereby the technical treatment is selected from the group consisting of polishing, pelleting, incrustation, and coloring. The technical treatment does not include a pesticide, an insecticide, a fungicide, or a nematicide.Beet Breeding Methods

[0136] The goal of beet breeding is to develop new, unique and superior beet cultivar and hybrids. The breeder initially selects and crosses two or more parental lines, followed by repeated selfing and selection, producing many new genetic combinations. Another method used to develop new, unique and superior beet cultivars occurs when the breeder selects andcrosses two or more parental lines followed by haploid induction and chromosome doubling that result in the development of dihaploid cultivars. The breeder can theoretically generate billions of different genetic combinations via crossing, selfing and mutations and the same is true for the utilization of the dihaploid breeding method.

[0137] Each year, the plant breeder selects the germplasm to advance to the next generation. This germplasm is grown under unique and different geographical, climatic and soil conditions, and further selections are then made, during and at the end of the growing season. The beet cultivars developed are unpredictable. This unpredictability is because the breeder's selection occurs in unique environments, with no control at the DNA level (using conventional breeding procedures or dihaploid breeding procedures), and with millions of different possible genetic combinations being generated. A breeder of ordinary skill in the art cannot predict the final resulting cultivars he develops, except possibly in a very gross and general fashion. This unpredictability results in the expenditure of large research monies to develop superior new beet cultivars.

[0138] The development of commercial beet cultivar requires the development and selection of beet plants, the crossing of these plants, and the evaluation of the crosses.

[0139] Pedigree breeding and recurrent selection breeding methods are used to develop cultivars from breeding populations. Breeding programs combine desirable traits from two or more cultivars or various broad-based sources into breeding pools from which cultivars are developed by selfing and selection of desired phenotypes or through the dihaploid breeding method followed by the selection of desired phenotypes. The new cultivars are evaluated to determine which have commercial potential.

[0140] Choice of breeding or selection methods depends on the mode of plant reproduction, the heritability of the trait(s) being improved, and the type of cultivar used commercially (e.g., Fi hybrid cultivar, pureline cultivar, etc.). For highly heritable traits, a choice of superior individual plants evaluated at a single location will be effective, whereas for traits with low heritability, selection should be based on mean values obtained from replicated evaluations of families of related plants. Popular selection methods commonly include pedigree selection, modified pedigree selection, mass selection, recurrent selection, and backcross breeding.

[0141] In some embodiments, the plants of the present disclosure can be used to produce new plant varieties. In some embodiments, the plants are used to develop new, unique and superior varieties or hybrids with desired phenotypes. As used herein, the term “plant breedingtechniques” comprises all of the plant breeding techniques disclosed in this section of the application, and well known to persons having skill in the art. Thus, in some embodiments, plant breeding methods encompass the application of recurrent selection, mass selection, hybridization, open-pollination, backcrossing, pedigree breeding, marker assisted selection breeding, mutation breeding, double haploids and chromosome doubling, gene editing, and combinations thereof.In some embodiments, selection methods, e.g., molecular marker assisted selection, can be combined with breeding methods to accelerate the process. Additional breeding methods have been known to one of ordinary skill in the art, e.g., methods discussed in Chahal and Gosal (Principles and procedures of plant breeding: biotechnological and conventional approaches, CRC Press, 2002, ISBN 084931321X, 9780849313219), Taji et al. (In vitro plant breeding, Routledge, 2002, ISBN 156022908X, 9781560229087), Richards (Plant breeding systems, Taylor & Francis US, 1997, ISBN 0412574500, 9780412574504), Hayes (Methods of Plant Breeding, Publisher: READ BOOKS, 2007, ISBN1406737062, 9781406737066), each of which is incorporated by reference in its entirety for all purposes. The Beta vulgaris (sugar beet) genome has been sequenced recently (Dohm et. al. (2014) The genome of the recently domesticated crop plant sugar beet (Beta vulgaris). Nature. 2014 Jan 23;505(7484):546- 9; Minoche et. al. (2015) Exploiting single-molecule transcript sequencing for eukaryotic gene prediction. Genome Biol. 2015 Sep 2; 16( 1): 184). Molecular markers for sugar beet plants are described in Moritani M, et al. (Identification of the predominant nonrestoring allele for Owen- type cytoplasmic male sterility in sugar beet (Beta vulgaris L.): development of molecular markers for the maintainer genotype. Mol Breed. 2013 Jun;32(l):91-100), Norouzi, P. et al. (Identification and Confirmation of New Molecular Markers Linked to The Fertility Restorer Genes in Sugar Beet. J. Crop Sci. Biotechnol. 21, 335-341 (2018), Annika Hjerdin Panagopoulos 2003. (Application of Molecular Markers in Sugar Beet Breeding, 2003. lucris.lub.lu.se / s / portalfiles / portal / 5776296 / 1693169.pdf), Shi et al., (Different molecular markers to identify the fertility of sugar beet monogerm germplasm resources, 2021, assets.researchsquare.com / files / rs-230220 / vl / 327c81e7-6b72-4f2d-9fdc-cb57eae50b00.pdf?c =1631883847), each of which is herein incorporated by reference in its entirety for all purposes.

[0142] In some embodiments, molecular markers are designed and made, based on the genome of the plants of the present application. In some embodiments, the molecular markers are selected from Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase ChainReaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs). Amplified Fragment Length Polymorphisms (AFLPs), and Simple Sequence Repeats (SSRs) which are also referred to as Microsatellites, etc. Methods of developing molecular markers and their applications are described by Avise (Molecular markers, natural history, and evolution, Publisher: Sinauer Associates, 2004, ISBN 0878930418, 9780878930418), Srivastava et al. (Plant biotechnology and molecular markers, Publisher: Springer, 2004, ISBN1402019114, 9781402019111), and Vienne (Molecular markers in plant genetics and biotechnology, Publisher: Science Publishers, 2003), each of which is incorporated by reference in its entirety for all purposes.

[0143] The molecular markers can be used in molecular marker assisted breeding. For example, the molecular markers can be utilized to monitor the transfer of the genetic material. In some embodiments, the transferred genetic material is a gene of interest, such as genes that contribute to one or more favorable agronomic phenotypes when expressed in a plant cell, a plant part, or a plant.

[0144] Details of existing sugar beet plants varieties and breeding methods are described in McGrath JM et al. (Plant Breeding Reviews Vol 42; Chapter 5. Sugar Beet Breeding, Wiley Moritani M, et al., 2018, onlinelibrary.wiley.com / doi / 10.1002 / 9781119521358.ch5), each of which is herein incorporated by reference in its entirety for all purposes.

[0145] Classical breeding methods can be included in the present disclosure to introduce one or more yellowing virus-resistant traits of the present disclosure into other plant varieties, or other close-related species that are compatible to be crossed with the transgenic plant. In some embodiments, the yellowing virus-resistant traits can be resistance against BMYV, BYV, BChV, BtMV, and BWYW, as disclosed in this application.

[0146] In some embodiments, said method comprises (i) crossing any one of the plants of the present disclosure resistant to yellowing virus (such as BMYV, BYV, BChV, BtMV, and BWYW) as a donor to a recipient plant line to create a Fl population; (ii) selecting offspring resistant to the yellowing virus. Optionally, the offspring can be further selected by testing or diagnosing the presence of QTLs taught herein.

[0147] In some embodiments, complete chromosomes or desired QTLs of the donor plant are transferred. For example, the yellowing virus-resistant plant with at least one of QTLs of the present disclosure can serve as a male or female parent in a cross pollination to produceoffspring plants, wherein by receiving the QTLs from the donor plant, the offspring plants have at least one of the QTLs.

[0148] In a method for producing plants having resistant to yellowing virus (such as BMYV, BYV, BChV, BtMV, and BWYW), protoplast fusion can also be used for the transfer of the transgene from a donor plant to a recipient plant. Protoplast fusion is an induced or spontaneous union, such as a somatic hybridization, between two or more protoplasts (cells in which the cell walls are removed by enzymatic treatment) to produce a single bi- or multi-nucleate cell. The fused cell that may even be obtained with plant species that cannot be interbred in nature is tissue cultured into a hybrid plant exhibiting the desirable combination of traits. More specifically, a first protoplast can be obtained from a plant resistant to yellowing virus. A second protoplast can be obtained from a second plant line, optionally from another plant species or variety, preferably from the same plant species or variety, that comprises commercially desirable characteristics, such as, but not limited to disease resistance, insect resistance, valuable grain characteristics (e.g., increased seed weight and / or seed size) etc. The protoplasts are then fused using traditional protoplast fusion procedures, which are known in the art to produce the cross.

[0149] Alternatively, embryo rescue may be employed in the transfer of the QTLs from a donor plant to a recipient plant. Embryo rescue can be used as a procedure to isolate embryos from crosses wherein plants fail to produce viable seed. In this process, the fertilized ovary or immature seed of a plant is tissue cultured to create new plants (see Pierik, 1999, In vitro culture of higher plants, Springer, ISBN 079235267x, 9780792352679, which is incorporated herein by reference in its entirety).

[0150] In some embodiments, the recipient plant is an elite line having one or more certain desired traits. Examples of desired traits include but are not limited to those that result in increased biomass production, production of specific chemicals, increased seed production, improved plant material quality, increased seed oil content, etc. Additional examples of desired traits include pest resistance, vigor, development time (time to harvest), enhanced nutrient content, novel growth patterns, aromas or colors, salt, heat, drought and cold tolerance, and the like. Desired traits also include selectable marker genes (e.g., genes encoding herbicide or antibiotic resistance used only to facilitate detection or selection of transformed cells), hormone biosynthesis genes leading to the production of a plant hormone (e.g., auxins, gibberellins, cytokinins, abscisic acid and ethylene that are used only for selection), or reporter genes (e.g. luciferase, [3-glucuronidase, chloramphenicol acetyl transferase (CAT, etc.). The recipient plantcan also be a plant with preferred chemical compositions, e.g., compositions preferred for medical use or industrial applications.

[0151] Classical breeding methods can be used to produce new varieties of beet according to the present disclosure. Newly developed Fl hybrids can be reproduced via asexual reproduction.

[0152] Open-Pollinated Populations. The improvement of open-pollinated populations of such crops as beet, rye, many maizes and sugar beets, herbage grasses, legumes such as alfalfa and clover, and tropical tree crops such as cacao, coconuts, oil palm and some rubber, depends essentially upon changing gene-frequencies towards fixation of favorable alleles while maintaining a high (but far from maximal) degree of heterozygosity. Uniformity in such populations is impossible and trueness-to-type in an open-pollinated variety is a statistical feature of the population as a whole, not a characteristic of individual plants. Thus, the heterogeneity of open-pollinated populations contrasts with the homogeneity (or virtually so) of inbred lines, clones and hybrids.

[0153] Population improvement methods fall naturally into two groups, those based on purely phenotypic selection, normally called mass selection, and those based on selection with progeny testing. Interpopulation improvement utilizes the concept of open breeding populations; allowing genes to flow from one population to another. Plants in one population (cultivar, strain, ecotype, or any germplasm source) are crossed either naturally (e.g., by wind) or by hand or by bees (commonly Apis mellifera L. or Megachile rotundata F. ) with plants from other populations. Selection is applied to improve one (or sometimes both) population(s) by isolating plants with desirable traits from both sources.

[0154] There are basically two primary methods of open-pollinated population improvement. First, there is the situation in which a population is changed en masse by a chosen selection procedure. The outcome is an improved population that is indefinitely propagatable by random-mating within itself in isolation. Second, the synthetic variety attains the same end result as population improvement but is not itself propagatable as such; it has to be reconstructed from parental lines or clones. These plant breeding procedures for improving open-pollinated populations are well known to those skilled in the art and comprehensive reviews of breeding procedures routinely used for improving cross-pollinated plants are provided in numerous texts and articles, including: Allard, Principles of Plant Breeding, John Wiley & Sons, Inc. (1960); Simmonds, Principles of Crop Improvement, Longman GroupLimited (1979); Hallauer and Miranda, Quantitative Genetics in Maize Breeding, Iowa State University Press (1981); and, Jensen, Plant Breeding Methodology, John Wiley & Sons, Inc. (1988).

[0155] Mass Selection. In mass selection, desirable individual plants are chosen, harvested, and the seed composited without progeny testing to produce the following generation. Since selection is based on the maternal parent only, and there is no control over pollination, mass selection amounts to a form of random mating with selection. As stated herein, the purpose of mass selection is to increase the proportion of superior genotypes in the population.

[0156] Mutation breeding is another method of introducing new traits into the beet plants of the present disclosure. Mutations that occur spontaneously or are artificially induced can be useful sources of variability for a plant breeder. The goal of artificial mutagenesis is to increase the rate of mutation for a desired characteristic. Mutation rates can be increased by many different means including temperature, long-term seed storage, tissue culture conditions, radiation; such as X-rays, Gamma rays (e.g., cobalt 60 or cesium 137), neutrons, (product of nuclear fission by uranium 235 in an atomic reactor), Beta radiation (emitted from radioisotopes such as phosphorus 32 or carbon 14), or ultraviolet radiation (preferably from 2500 to 2900 nm), or chemical mutagens (such as base analogues (5 -bromo-uracil)), related compounds (8-ethoxy caffeine), antibiotics (streptonigrin), alkylating agents (sulfur mustards, nitrogen mustards, epoxides, ethyleneamines, sulfates, sulfonates, sulfones, lactones), azide, hydroxylamine, nitrous acid, or acridines. Once a desired trait is observed through mutagenesis the trait may then be incorporated into existing germplasm by traditional breeding techniques. Details of mutation breeding can be found in Allard, Principles of Plant Breeding, John Wiley & Sons, Inc. (1960). In addition, mutations created in other beet plants may be used to produce a backcross conversion of beet plants having at least one of QTLs taught herein while comprising the mutation obtained from the other beet or Beta plants.

[0157] Double Haploids and Chromosome Doubling. One way to obtain homozygous plants without the need to cross two parental lines followed by a long selection of the segregating progeny, and / or multiple backcrossing is to produce haploids and then double the chromosomes to form doubled haploids. Haploid plants can occur spontaneously or may be artificially induced via chemical treatments or by crossing plants with inducer lines (Seymour et al. 2012, PNAS vol 109, pg 4227-4232; Zhang et al., 2008 Plant Cell Rep. Dec 27(12) 1851-60). The production of haploid progeny can occur via a variety of mechanisms which can affect the distribution of chromosomes during gamete formation. The chromosome complements ofhaploids sometimes double spontaneously to produce homozygous doubled haploids (DHs). Mixopioids, which are plants which contain cells having different ploidies, can sometimes arise and may represent plants that are undergoing chromosome doubling so as to spontaneously produce doubled haploid tissues, organs, shoots, floral parts or plants. Another common technique is to induce the formation of double haploid plants with a chromosome doubling treatment such as colchicine (El-Hennawy et al., 2011 Vol 56, issue 2 pages 63-72; Doubled Haploid Production in Crop Plants 2003 edited by Maluszynski ISBN 1-4020-1544-5). The production of doubled haploid plants yields highly uniform cultivars and is especially desirable as an alternative to sexual inbreeding of longer-generation crops. By producing doubled haploid progeny, the number of possible gene combinations for inherited traits is more manageable. Thus, an efficient doubled haploid technology can significantly reduce the time and the cost of inbred and cultivar development.

[0158] Additional methods include, but are not limited to, expression vectors introduced into plant tissues using a direct gene transfer method, such as microprojectile-mediated delivery, DNA injection, electroporation, and the like. Additionally, expression vectors are introduced into plant tissues by using either microprojectile-mediated delivery with a biolistic device or by using Agrobacterium-mediated transformation. Transformant plants obtained with the protoplasm of the subject beet plants are intended to be within the scope of the embodiments of the application.

[0159] Synthetics. A synthetic variety is produced by crossing inter se a number of genotypes selected for good combining ability in all possible hybrid combinations, with subsequent maintenance of the variety by open pollination. Whether parents are (more or less inbred) seed- propagated lines, makes no difference in principle. Parents are selected on general combining ability, sometimes by test crosses or topcrosses, more generally by polycrosses. Parental seed lines may be deliberately inbred (e.g. by selfing or sib crossing). However, even if the parents are not deliberately inbred, selection within lines during line maintenance will ensure that some inbreeding occurs. Clonal parents will, of course, remain unchanged and highly heterozygous.

[0160] Whether a synthetic can go straight from the parental seed production plot to the farmer or must first undergo one or two cycles of multiplication depends on seed production and the scale of demand for seed.

[0161] While mass selection is sometimes used, progeny testing is generally preferred for polycrosses, because of their operational simplicity and obvious relevance to the objective, namely exploitation of general combining ability in a synthetic.

[0162] The numbers of parental lines or clones that enter a synthetic vary widely. In practice, numbers of parental lines range from 10 to several hundred, with 100-200 being the average. Broad based synthetics formed from 100 or more clones would be expected to be more stable during seed multiplication than narrow based synthetics.

[0163] Pedigreed varieties. A pedigreed variety is a superior genotype developed from selection of individual plants out of a segregating population followed by propagation and seed increase of self-pollinated offspring and careful testing of the genotype over several generations. This is an open pollinated method that works well with naturally self-pollinating species. This method can be used in combination with mass selection in variety development. Variations in pedigree and mass selection in combination are the most common methods for generating varieties in self-pollinated crops.

[0164] Hybrids. A hybrid is an individual plant resulting from a cross between parents of differing genotypes. Commercial hybrids are now used extensively in many crops, including com (maize), sorghum, sugar beet, sunflower and broccoli. Hybrids can be formed in a number of different ways, including by crossing two parents directly (single cross hybrids), by crossing a single cross hybrid with another parent (three-way or triple cross hybrids), or by crossing two different hybrids (four-way or double cross hybrids).

[0165] Strictly speaking, most individuals in an out breeding (i.e., open-pollinated) population are hybrids, but the term is usually reserved for cases in which the parents are individuals whose genomes are sufficiently distinct for them to be recognized as different species or subspecies. Hybrids may be fertile or sterile depending on qualitative and / or quantitative differences in the genomes of the two parents. Heterosis, or hybrid vigor, is usually associated with increased heterozygosity that results in increased vigor of growth, survival, and fertility of hybrids as compared with the parental lines that were used to form the hybrid. Maximum heterosis is usually achieved by crossing two genetically different, highly inbred lines.

[0166] Targeting Induced Local Lesions in Genomes (TILLING). Breeding schemes of the present disclosure can include crosses with TILLING® plant lines. TILLING® is a method in molecular biology that allows directed identification of mutations in a specific gene. TILLING® was introduced in 2000, using the model plant Arabidopsis thaliana. TILLING®has since been used as a reverse genetics method in other organisms such as zebrafish, com, wheat, rice, soybean, tomato and lettuce. The method combines a standard and efficient technique of mutagenesis with a chemical mutagen (e.g., Ethyl methane sulfonate (EMS)) with a sensitive DNA screening-technique that identifies single base mutations (also called point mutations) in a target gene. EcoTILLING is a method that uses TILLING® techniques to look for natural mutations in individuals, usually for population genetics analysis (see Comai, et al. , 2003 The Plant Journal 37, 778-786; Gilchrist et al.2006 Mol. Ecol. 15, 1367-1378; Mejlhede et al.2006 Plant Breeding 125, 461-467; Nieto et al.2001 BMC Plant Biology 7, 34-42, each of which is incorporated by reference hereby for all purposes). DEcoTILLING is a modification of TILLING® and EcoTILLING which uses an inexpensive method to identify fragments (Garvin et al., 2007, DEco-TILLING: An inexpensive method for SNP discovery that reduces ascertainment bias. Molecular Ecology Notes 7, 735-746). More detailed description on methods and compositions on TILLING® can be found in US 5994075, US 2004 / 0053236 Al, WO 2005 / 055704, and WO 2005 / 048692, each of which is hereby incorporated by reference for all purposes.

[0167] In some embodiments, TILLING® can also be utilized for plants of the Beta genus including beet plants. Thus, in some embodiments, the breeding methods of the present disclosure include breeding with one or more TILLING plant lines with one or more identified mutations.

[0168] Gene editing technologies. Breeding and selection schemes of the present disclosure can include crosses with plant lines that have undergone genome editing. In some embodiments, the breeding and selection methods of the present disclosure are compatible with plants that have been modified using any gene and / or genome editing tool, including, but not limited to: ZFNs, TALENS, CRISPR, and Mega nuclease technologies. In some embodiments, persons having skill in the art will recognize that the breeding methods of the present disclosure are compatible with many other gene editing technologies. In some embodiments, the present disclosure teaches gene-editing technologies can be applied for a single locus conversion, for example, conferring beet plant with virus resistance. In some embodiments, the present disclosure teaches that the single locus conversion is an artificially mutated gene or nucleotide sequence that has been modified through the use of breeding techniques taught herein.

[0169] In some embodiments, the breeding and selection methods of the present disclosure are compatible with plants that have been modified through Zinc Linger Nucleases. Three variants of the ZFN technology are recognized in plant breeding (with applications ranging fromproducing single mutations or short deletions / insertions in the case of ZFN- 1 and -2 techniques up to targeted introduction of new genes in the case of the ZFN-3 technique); 1) ZFN- 1 : Genes encoding ZFNs are delivered to plant cells without a repair template. The ZFNs bind to the plant DNA and generate site specific double-strand breaks (DSBs). The natural DNA-repair process (which occurs through nonhomologous end-joining, NHEJ) leads to site specific mutations, in one or only a few base pairs, or to short deletions or insertions; 2) ZFN -2: Genes encoding ZFNs are delivered to plant cells along with a repair template homologous to the targeted area, spanning a few kilo base pairs. The ZFNs bind to the plant DNA and generate site-specific DSBs. Natural gene repair mechanisms generate site-specific point mutations e.g. changes to one or a few base pairs through homologous recombination and the copying of the repair template; and 3) ZFN-3: Genes encoding ZFNs are delivered to plant cells along with a stretch of DNA which can be several kilo base pairs long and the ends of which are homologous to the DNA sequences flanking the cleavage site. As a result, the DNA stretch is inserted into the plant genome in a site-specific manner.

[0170] In some embodiments, the breeding and selection methods of the present disclosure are compatible with plants that have been modified through Transcription activator-like (TAL) effector nucleases (TALENs). TALENS are polypeptides with repeat polypeptide arms capable of recognizing and binding to specific nucleic acid regions. By engineering the polypeptide arms to recognize selected target sequences, the TAL nucleases can be used to direct double stranded DNA breaks to specific genomic regions. These breaks can then be repaired via recombination to edit, delete, insert, or otherwise modify the DNA of a host organism. In some embodiments, TALENSs are used alone for gene editing (e.g., for the deletion or disruption of a gene). In other embodiments, TALs are used in conjunction with donor sequences and / or other recombination factor proteins that will assist in the Non-homologous end joining (NHEJ) process to replace the targeted DNA region. For more information on the TAL-mediated gene editing compositions and methods of the present disclosure, see US Patent Nos. 8,440,432; US 8,450,471; US 8,586,526; US 8,586,363; US 8,592,645; US 8,697,853; 8,704,041; 8,921,112; and 8,912,138, each of which is hereby incorporated in its entirety for all purposes.

[0171] In some embodiments, the breeding and selection methods of the present disclosure are compatible with plants that have been modified through Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) or CRISPR-associated (Cas) gene editing tools. CRISPR proteins were originally discovered as bacterial adaptive immunity systems which protected bacteria against viral and plasmid invasion. There are at least three main CRISPR system types(Type I, II, and III) and at least 10 distinct subtypes (Makarova, K.S., et.al., Nat Rev Microbiol. 2011 May 9; 9(6):467-477). Type I and III systems use Cas protein complexes and short guide polynucleotide sequences to target selected DNA regions. Type II systems rely on a single protein (e.g. Cas9) and the targeting guide polynucleotide, where a portion of the 5’ end of a guide sequence is complementary to a target nucleic acid. Formore information on the CRISPR gene editing compositions and methods of the present disclosure, see US Patent Nos. 8,697,359; 8,889,418; 8,771,945; and 8,871,445, each of which is hereby incorporated in its entirety for all purposes.

[0172] In some embodiments, the breeding and selection methods of the present disclosure are compatible with plants that have been modified through meganucleases. In some embodiments, meganucleases are engineered endonucleases capable of targeting selected DNA sequences and inducing DNA breaks. In some embodiments, new meganucleases targeting specific regions are developed through recombinant techniques which combine the DNA binding motifs from various other identified nucleases. In other embodiments, new meganucleases are created through semi-rational mutational analysis, which attempts to modify the structure of existing binding domains to obtain specificity for additional sequences. For more information on the use of meganucleases for genome editing, see Silva et al., 2011 Current Gene Therapy 11 pg 11-27; and Stoddard et al., 2014 Mobile DNA 5 pg 7, each of which is hereby incorporated in its entirety for all purposes.Quantitative Trait Loci

[0173] Breeding schemes of the present application can include crosses between donor and recipient plants. In some embodiments said donor plants contain a gene or genes of interest which may confer the plant with a desirable phenotype. The recipient line can be an elite line or cultivar having certain favorable traits for commercial production. In one embodiment, the elite line may contain other genes that also impart said line with the desired phenotype. When crossed together, the donor and recipient plant may create a progeny plant with combined desirable loci which may provide quantitatively additive effect of a particular characteristic. In that case, QTL mapping can be involved to facilitate the breeding process.

[0174] QTL mapping can be applied to determine the parts of the donor plant’s genome conferring the desirable phenotype, and facilitate the breeding methods. Inheritance of quantitative traits or polygenic inheritance refers to the inheritance of a phenotypic characteristic that varies in degree and can be attributed to the interactions between two or more genes and their environment. Though not necessarily genes themselves, quantitative trait lociare stretches of DNA that are closely linked to the genes that underlie the trait in question. QTLs can be molecularly identified to help map regions of the genome that contain genes involved in specifying a quantitative trait. This can be an early step in identifying and sequencing these genes.

[0175] A quantitative trait locus (QTL) is a region of DNA that is associated with a particular phenotypic trait. Typically, QTLs underlie continuous traits (those traits that vary continuously, e.g. yield, height, level of resistance to virus, etc.) as opposed to discrete traits (traits that have two or several character values, e.g. smooth vs. wrinkled peas used by Mendel in his experiments).

[0176] Molecular markers are used for the visualization of differences in nucleic acid sequences. This visualization is possible due to, for example, DNA-DNA hybridization techniques (RFLP) and / or due to techniques using the polymerase chain reaction (e.g. STS, SNPs, microsatellites, AFLP).

[0177] All differences between two parental genotypes will segregate in a mapping population based on the cross of these parental genotypes. The segregation of the different markers may be compared and recombination frequencies can be calculated. The recombination frequencies of molecular markers on different chromosomes are generally 50%. Between molecular markers located on the same chromosome the recombination frequency depends on the distance between the markers. A low recombination frequency usually corresponds to a low distance between markers on a chromosome. Comparing all recombination frequencies will result in the most logical order of the molecular markers on the chromosomes. This most logical order can be depicted in a linkage map (Paterson, 1996, Genome Mapping in Plants. R.G. Landes, Austin.). A group of adjacent or contiguous markers on the linkage map that is associated to a reduced disease incidence and / or a reduced lesion growth rate pinpoints the position of a QTL.

[0178] The nucleic acid sequence of a QTL may be determined by methods known to the skilled person. For instance, a nucleic acid sequence comprising said QTL, or a resistanceconferring part thereof may be isolated from a donor plant by fragmenting the genome of said plant and selecting those fragments harboring one or more markers indicative of said QTL. Subsequently, or alternatively, the marker sequences (or parts thereof) indicative of said QTL may be used as (PCR) amplification primers, in order to amplify a nucleic acid sequence comprising said QTL from a genomic nucleic acid sample or a genome fragment obtained from said plant. The amplified sequence may then be purified in order to obtain the isolated QTL.The nucleotide sequence of the QTL, and / or of any additional markers comprised therein, may then be obtained by standard sequencing methods.

[0179] One or more such QTLs associated with a desirable trait in a donor plant can be transferred to a recipient plant to incorporate the desirable trait into progeny plants by transferring and / or breeding methods.

[0180] Isogenic lines in which favorable QTL alleles have been fixed can be generated by systematic backcrossing. These isogenic lines may be referred to as near-isogenic lines (NILs), introgression lines (ILs), backcross inbred lines (BILs), backcross recombinant inbred lines (BCRIL), recombinant chromosome substitution lines (RCSLs), chromosome segment substitution lines (CSSLs), and stepped aligned inbred recombinant strains (STAIRSs).Breeding Evaluation

[0181] Each breeding program can include a periodic, objective evaluation of the efficiency of the breeding procedure. Evaluation criteria vary depending on the goal and objectives, but should include gain from selection per year based on comparisons to an appropriate standard, overall value of the advanced breeding lines, and number of successful cultivars produced per unit of input (e.g., per year, per dollar expended, etc.).

[0182] Promising advanced breeding lines are thoroughly tested per se and in hybrid combination and compared to appropriate standards in environments representative of the commercial target area(s). The best lines are candidates for use as parents in new commercial cultivars; those still deficient in a few traits may be used as parents to produce new populations for further selection or in a backcross program to improve the parent lines for a specific trait.

[0183] In one embodiment, the plants are selected on the basis of one or more phenotypic traits. Skilled persons will readily appreciate that such traits include any observable characteristic of the plant, including for example growth rate, vigor, plant health, maturity, branching, plant height, leaf coverage, weight, total yield, color, taste, sugar levels, aroma, changes in the production of one or more compounds by the plant (including for example, metabolites, proteins, drugs, carbohydrates, oils, and any other compounds).

[0184] A most difficult task is the identification of individuals that are genetically superior, because for most traits the true genotypic value is masked by other confounding plant traits or environmental factors. One method of identifying a superior plant is to observe its performance relative to other experimental plants and to a widely grown standard cultivar. If a singleobservation is inconclusive, replicated observations provide a better estimate of its genetic worth.

[0185] Proper testing should detect any major faults and establish the level of superiority or improvement over current cultivars. In addition to showing superior performance, there must be a demand for a new cultivar that is compatible with industry standards or which creates a new market. The introduction of a new cultivar will incur additional costs to the seed producer, the grower, processor and consumer; for special advertising and marketing, altered seed and commercial production practices, and new product utilization. The testing preceding release of a new cultivar should take into consideration research and development costs as well as technical superiority of the final cultivar. For seed-propagated cultivars, it must be feasible to produce seed easily and economically.

[0186] It should be appreciated that in certain embodiments, plants may be selected based on the absence, suppression or inhibition of a certain feature or trait (such as an undesirable feature or trait) as opposed to the presence of a certain feature or trait (such as a desirable feature or trait).

[0187] Selecting plants based on genotypic information is also envisaged (for example, including the pattern of plant gene expression, genotype, or presence of genetic markers). Where the presence of one or more genetic marker is assessed, the one or more marker may already be known and / or associated with a particular characteristic of a plant; for example, a marker or markers may be associated with an increased growth rate or metabolite profile. This information could be used in combination with assessment based on other characteristics in a method of the disclosure to select for a combination of different plant characteristics that may be desirable. Such techniques may be used to identify novel quantitative trait loci (QTLs). By way of example, plants may be selected based on growth rate, size (including but not limited to weight, height, leaf size, stem size, branching pattern, or the size of any part of the plant), general health, survival, tolerance to adverse physical environments and / or any other characteristic, as described herein before.

[0188] Further non-limiting examples include selecting plants based on: speed of seed germination; quantity of biomass produced; increased root, and / or leaf / shoot growth that leads to an increased yield (herbage or grain or fiber or oil) or biomass production; effects on plant growth that results in an increased root and / or seed yield for a crop; effects on plant growth which result in an increased head yield; effects on plant growth that lead to an increasedresistance or tolerance to disease including fungal, viral or bacterial diseases, to mycoplasma, or to pests such as insects, mites or nematodes in which damage is measured by decreased foliar symptoms such as the incidence of bacterial or fungal lesions, or area of damaged foliage or reduction in the numbers of nematode cysts or galls on plant roots, or improvements in plant yield in the presence of such plant pests and diseases; effects on plant growth that lead to increased metabolite yields; effects on plant growth that lead to improved aesthetic appeal which may be particularly important in plants grown for their form, color or taste, for example the color intensity of beet leaves / roots, or the taste of said leaves / roots.Molecular Breeding Evaluation Techniques

[0189] Selection of plants based on phenotypic or genotypic information may be performed using techniques such as, but not limited to: high through-put screening of chemical components of plant origin, sequencing techniques including high through-put sequencing of genetic material, differential display techniques (including DDRT-PCR, and DD-PCR), nucleic acid microarray techniques, RNA-seq (Transcriptome Sequencing), qPCR (quantitative real time PCR) and RT-qPCR (reverse transcriptase quantitative real time PCR).

[0190] In one embodiment, the evaluating step of a plant breeding program involves the identification of desirable traits in progeny plants. Progeny plants can be grown in, or exposed to conditions designed to emphasize a particular trait (e.g. drought conditions for drought tolerance, lower temperatures for freezing tolerant traits). Progeny plants with the highest scores for a particular trait may be used for subsequent breeding steps.

[0191] In some embodiments, plants selected from the evaluation step can exhibit a 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 120% or more improvement in a particular plant trait compared to a control plant.

[0192] In other embodiments, the evaluating step of plant breeding comprises one or more molecular biological tests for genes or other markers. For example, the molecular biological test can involve probe hybridization and / or amplification of nucleic acid (e.g., measuring nucleic acid density by Northern or Southern hybridization, PCR) and / or immunological detection (e.g., measuring protein density, such as precipitation and agglutination tests, ELISA (e.g., Lateral Flow test or DAS-ELISA), Western blot, immune labeling, immunosorbent electron microscopy (ISEM), and / or dot blot).

[0193] The procedure to perform a nucleic acid hybridization, an amplification of nucleic acid (e.g., PCR, RT-PCR) or an immunological detection (e.g., precipitation and agglutination tests, ELISA (e.g., Lateral Flow test or DAS-ELISA), Western blot, RIA, immunogold or immunofluorescent labeling, immunosorbent electron microscopy (ISEM), and / or dot blot tests) are performed as described elsewhere herein and well-known by one skilled in the art.

[0194] In one embodiment, the evaluating step comprises PCR (semi-quantitative or quantitative), wherein primers are used to amplify one or more nucleic acid sequences of a desirable gene, or a nucleic acid associated with said gene, or QTL or a desirable trait (e.g., a co-segregating nucleic acid, or other marker).

[0195] In another embodiment, the evaluating step comprises immunological detection (e.g., precipitation and agglutination tests, ELISA (e.g., Lateral Flow test or DAS-ELISA), Western blot, RIA, immuno labeling (gold, fluorescent, or other detectable marker), immunosorbent electron microscopy (ISEM), and / or dot blot), wherein one or more gene or marker-specific antibodies are used to detect one or more desirable proteins. In one embodiment, said specific antibody is selected from the group consisting of polyclonal antibodies, monoclonal antibodies, antibody fragments, and combination thereof.

[0196] Reverse Transcription Polymerase Chain Reaction (RT-PCR) can be utilized in the present disclosure to determine expression of a gene to assist during the selection step of a breeding scheme. It is a variant of polymerase chain reaction (PCR), a laboratory technique commonly used in molecular biology to generate many copies of a DNA sequence, a process termed “amplification”. In RT-PCR, however, RNA strand is first reverse transcribed into its DNA complement (complementary DNA, or cDNA) using the enzyme reverse transcriptase, and the resulting cDNA is amplified using traditional or real-time PCR.

[0197] Real time RT-PCR provides a method where the amplicons can be visualized as the amplification progresses using a fluorescent reporter molecule. There are three major kinds of fluorescent reporters used in real time RT-PCR, general non-specific DNA Binding Dyes such as SYBR Green I, TaqMan Probes and Molecular Beacons (including Scorpions).

[0198] Other forms of nucleic acid detection can include next-generation sequencing methods such as DNA SEQ or RNA SEQ using any known sequencing platform including, but not limited to: Roche 454, Solexa Genome Analyzer, AB SOLiD, Illumina GA / HiSeq, Ion PGM, Mi Seq, among others (Liu et al,. 2012 Journal of Biomedicine and Biotechnology Volume2012 ID 251364; Franca et al., 2002 Quarterly Reviews of Biophysics 35 pg 169-200; Mardis 2008 Genomics and Human Genetics vol 9 pg 387-402).

[0199] In other embodiments, nucleic acids may be detected with other high-throughput hybridization technologies including microarrays, gene chips, LNA probes, nanoStrings, and fluorescence polarization detection, among others.

[0200] In some embodiments, detection of markers can be achieved at an early stage of plant growth by harvesting a small tissue sample (e.g., branch, or leaf disk). This approach is preferable when working with large populations as it allows breeders to weed out undesirable progeny at an early stage and conserve growth space and resources for progeny which show more promise. In some embodiments the detection of markers is automated, such that the detection and storage of marker data is handled by a machine. Recent advances in robotics have also led to full-service analysis tools capable of handling nucleic acid / protein marker extractions, detection, storage and analysis.Methods of identifying, selecting, producing sugar beet plants resistant to yellowing virus(es)

[0201] There are numerous steps in the development of any novel, desirable plant germplasm. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germplasm, the establishment of program goals, and the definition of specific breeding objectives.

[0202] The next step is selection of germplasm that possesses the traits to meet the program goals. The goal is to combine in a single variety or hybrid an improved combination of desirable traits from the parental germplasm.

[0203] In beet, these important traits may include higher yield of roots or leaves, improved leaf color, consistent leaf color at the juvenile stage in warm as well as cool conditions, agronomic quality such as sugar level, root size, root color or texture, root firmness, resistance to diseases and insects, adaptability for soil and climate conditions, harvest flexibility, tolerance to drought and heat, improved post-harvest shelf-life of the leaves or postharvest quality of roots, improved standing ability in the field, improved uniformity of leaves or roots, improved bolting tolerance in seed production, improved seedling vigor, and the like.

[0204] In some embodiments, receivers of the desired traits (e.g., a recurrent parent) can be any susceptible individual belonging to a species crossable with sugar beet such as members of the Beta vulgaris ssp. vulgaris group which includes crops such as sugarbeet, chard, beetrootand mangold but also closely related species such as Beta vulgaris ssp. maritima or any other member of the Betoideae family able to produce viable offspring when crossed with Beta vulgaris ssp. vulgaris.

[0205] In further embodiments, a plant of the present disclosure can be crossed with a .Be genus plant that is crossable (e.g., sexually compatible). The genus Beta, to which B. vulgaris belongs, is comprised of 15 recognized species which are divided into four sections: Beta, Corollinae, Procumbentes and Nanae. First, hybridization between B. vulgaris and specific members within the Beta section (i.e. fodder beet, red beet, leaf beet, Swiss chard) can occur. Successful hybridization events between B. vulgaris and relatives of Western European origin; B. maritima, B. macrocarpa and B. atriphcifoha (BRIDGE, 1993). Hybrids of B. vulgaris and B. maritima are fertile and show compatibility at the chromosomal level (Forster et al., 1997). Hybrids between B. macrocarpa and B. vulgaris have caused weed problems in European sugar beet fields (McFarlane, 1975). Second, artificial hybrids have been produced with species in the section Corollinae. However, such hybrids are highly sterile and few plants set seed when backcrossed to sugar beet. Third, artificial hybrids between sugar beet and members of the genus Procumbentes have been produced with great difficulty. The hybrids become necrotic and die at the seedling stage. The chromosomes of the species of section Procumbentes do not pair with those of the genus Beta (Van Geyt et al., 1990).

[0206] In some embodiments, the present disclosure teaches an interspecific cross of a beet of the present disclosure with another species in the genus Beta and / or an intergeneric cross of a beet of the present disclosure with another species not in the genus Be ta, but in the same family Amaranthaceae.

[0207] In some embodiments, commercial lines of interest can be used as a receiver of desired trait(s) of the present disclosure by breeding and / or introgressing. An exemplary list of the commercial lines are presented in Table 1.Table 1

[0208] In some embodiments, particularly desirable traits that may be incorporated by this disclosure are improved resistance to different bacterial fungal, and viral pathogens. Important diseases include but are not limited to (i) bacterial diseases such as Bacterial blight (Pseudomonas syringae pv. Apiaia). Bacterial pocket (Xanthomonas helicoid). Bacterial soft rot (Envinia carotovora subsp. Carotovora), Bacterial vascular necrosis and rot (Envinia carotovora subsp. Betavasculorum), Crown gall (Agrohacterium tumefaciens), Silvering disease (Curtohacterium flaccumfaciens pv. hetae=Corynehacterium betae)’. (ii) fungal disease such as Altemaria leaf spot (Alternaria alternata; Alternaria brassicae), Anthracnose (Colletotrichum dematium), Aphanomyces root rot (black root; Aphanomyces cochlioides). Black wood vessel (Pythium irregulare), Cercospora leaf spot (Cercospora beticoki), Charcoal rot (Macrophomina phaseolina), Choanephora rot (Choanephora cucurbitarum), Damping-off, black leg, black root and seedling blight (Aphanomyces cochlioides; Cylindrocladium spp. Fusarium spp.; Phoma betae Pleospora; betae; Pythium spp.; Rhizoctonia solani; Thanatephorus cucumeris), Downy mildew (Peronospora farinosa; Peronospora schachtii), Fusarium yellows (Fusarium oxysporum), Fusarium yellows and root rot (Fusarium oxysporum f.sp. betae), Leaf gall (beet tumor, or crown wart; Physoderma leproides), Phoma leaf spot and root rot (Phoma betae), Phymatotrichum root rot (cotton root rot; Phymatotrichopsis omnivora), Phytophthora wet rot (Phytophthora drechsleri), Powdery mildew (Erysiphe polygoni), Pythium root rot (Pythium aphanidermatum; Pythium deliense), Ramularia leaf spot (Ramularia beticola), Rhizoctonia foliar blight, crown and root rot (Rhizoctonia solani), Rhizopus root rot (Rhizopus arrhizus; Rhizopus stolonifer), Rust (Uromyces betae), Sclerotinia crown & root rot (Sclerotinia sclerotiorum), Seedling rust (Puccinia subnitens), Slime molds (Physarum cinereum), Southern blight (Sclerotium root rot and stem rot; Sclerotium rolfsii; Athelia rolfsii), Stemphylium leaf spot (Stemphylium botryosum; Pleospora tarda), Storage rots (Botrytis cinerea: Botryotinia fuckeliana; Penicillium spp.: Phoma betae), Verticillium wilt (Verticillium albo-atrum), Violet root rot (Helicobasidium brebissonii; Rhizoctonia crocorum); (iii) viral diseases such as Alfalfa mosaic virus (AMV), Beet curly top virus (BCTV), Beet distortion mosaic virus, Beet leaf curl virus (BCLV), Beet western yellows virus (BMY), Beet mosaic virus (BtMV), Beet yellow net virus (BYNV), Beet yellows virus (BYV),Cucumber mosaic virus (CMV), Lettuce infectious yellows virus (LIYV), and Beet necrotic yellow vein virus (BNYVV).

[0209] Also, improved resistance to insect pests is another desirable trait that may be incorporated into new beet plants developed by this disclosure. Insect pests affecting the various species of beet include Sugar beet root aphids (Pemphigus populivenae betae), Beet leaf miner (Pegomya hyoscyami), Beet webworms (Loxostege sticticalis), Blister beetles (Pyrota lineata), European Com Borers, Flea beetles (Psylliodes punctulata melsheimer), Sugar beet maggots (Tetanops myopaeformis) sugar beet nematodes (Heterodera schachiii)' and root not nematodes (Meloidogyne spp.) and vegetable weevils.

[0210] The present disclosure teaches additional desirable traits of disease resistance that can be combined with the yellowing vims resistant trait. That is, these additional desirable traits can be stacked with yellowing disease resistant traits taught herein. The disease resistant traits include, but are not limited to, resistances against the following: Cercospora beticola Aphanomyces cochlioides, Heterodera schachtii, Beet necrotic yellow vein virus, Rhizoctonia solani, Pemphigus populivenae betae, Uromyces betae, Peronospora farinose, and Fusarium oxysporum.

[0211] In other embodiments, biotechnological traits can be incorporated to the new beet plants of the present disclosure having resistance against yellowing vims(es). The biotechnological traits include, but are not limited to, Roundup ready (H7-1), Acetolactate Synthase (ALS)- resistance, and Protoporphyrinogen Oxidase (PPO)-resistance.

[0212] Other important traits to be stacked with the yellowing vims resistance are as follows; Cytosolic male sterility (CMS), Genetic male sterility (GMS), Bolting resistance, Hypocotyl colour, Genetic haploid induction systems, extreme bolting tolerance (“winter beet”) and changes in carbon metabolism to achieve higher sugar contents.

[0213] In some embodiments, the present disclosure teaches methods of using molecular markers taught herein for selection of BMYV -resistant plants.

[0214] In some embodiments, the present disclosure teaches methods of selecting or identifying a plant comprising a resistance against Beet Mild Yellow Vims (BMYV), said method comprising the steps of: (a) screening for the presence of at least one QTL allele, such as a QTL allele associated with resistance against BMYV), wherein said QTL is selected from the group consisting of QTL1, QTL2, QTL3, and QTL4, wherein QTL1 located on chromosome 1 is genetically linked to at least one marker loci selected from the groupconsisting of PBV504245, PBV125552, PBV291217, PBV369685, PBV261963, PBV757437, PBV638722, and EPBV6296; wherein QTL2 located on chromosome 4 is genetically linked to at least one marker loci selected from the group consisting of PBV577030, PBV562771, PBV573138, PBV273480, and PBV821051, wherein QTL3 located on chromosome 8 is genetically linked to at least one marker loci selected from the group consisting of PB VI 48969, PBV331644, PBV882826, PBV374371, PBV757436, PBV738292, PBV738293, and EPBV7349; and wherein QTL4 located on chromosome 2 is genetically linked to at least one marker loci selected from the group consisting of GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821; and (b) isolating a plant which tested positive from said at least one QTL comprising the resistance against BMYV).

[0215] In some embodiments, the screening for the presence of QTL1 comprises at least one of: PCR amplification of DNA with SEQ ID NO: 2 and SEQ ID NO: 3, PCR amplification of DNA with SEQ ID NO: 5 and SEQ ID NO: 6, PCR amplification of DNA with SEQ ID NO: 8 and SEQ ID NO: 9, PCR amplification of DNA with SEQ ID NO: 11 and SEQ ID NO: 12, PCR amplification of DNA with SEQ ID NO: 14 and SEQ ID NO: 15, PCR amplification of DNA with SEQ ID NO: 52 and SEQ ID NO: 54, PCR amplification of DNA with SEQ ID NO: 56 and SEQ ID NO: 57, and PCR amplification of DNA with SEQ ID NO: 58 and SEQ ID NO: 60.

[0216] In some embodiments, the screening for the presence of QTL2 comprises at least one of: PCR amplification of DNA with SEQ ID NO: 17 and SEQ ID NO: 18, PCR amplification of DNA with SEQ ID NO: 20 and SEQ ID NO: 21, PCR amplification of DNA with SEQ ID NO: 23 and SEQ ID NO: 24, PCR amplification of DNA with SEQ ID NO: 26 and SEQ ID NO: 27, and PCR amplification of DNA with SEQ ID NO: 29 and SEQ ID NO: 30.

[0217] In some embodiments, the screening for the presence of QTL3 comprises at least one of: PCR amplification of DNA with SEQ ID NO: 32 and SEQ ID NO: 33, PCR amplification of DNA with SEQ ID NO: 35 and SEQ ID NO: 36, PCR amplification of DNA with SEQ ID NO: 38 and SEQ ID NO: 39, PCR amplification of DNA with SEQ ID NO: 41 and SEQ ID NO: 42, PCR amplification of DNA with SEQ ID NO: 44 and SEQ ID NO: 45, PCR amplification of DNA with SEQ ID NO: 62 and SEQ ID NO: 63, PCR amplification of DNA with SEQ ID NO: 65 and SEQ ID NO: 66, and PCR amplification of DNA with SEQ ID NO: 67 and SEQ ID NO: 69.

[0218] In some embodiments, the screening for the presence of QTL4 comprises at least one of: PCR amplification of DNA with SEQ ID NO: 70 and SEQ ID NO: 72, PCR amplification of DNA with SEQ ID NO: 73 and SEQ ID NO: 75, PCR amplification of DNA with SEQ ID NO: 76 and SEQ ID NO: 78, PCR amplification of DNA with SEQ ID NO: 79 and SEQ ID NO: 81, PCR amplification of DNA with SEQ ID NO: 83 and SEQ ID NO: 84, and PCR amplification of DNA with SEQ ID NO: 85 and SEQ ID NO: 87.

[0219] In further embodiments, a marker for selection of Beet Mild Yellowing Virus resistant plants is selected from the group consisting of SEQ ID NO: 1 to SEQ ID NO: 45 and SEQ ID NO: 52 to SEQ ID NO: 87. The marker of the present disclosure utilizes a sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 29, SEQ ID NO: 32, SEQ ID NO: 35, SEQ ID NO: 38, SEQ ID NO: 41, SEQ ID NO: 44, SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 58, SEQ ID NO: 62, SEQ ID NO: 65, SEQ ID NO: 67, SEQ ID NO: 70, SEQ ID NO: 73, SEQ ID NO: 76, SEQ ID NO: 79, SEQ ID NO: 83, and SEQ ID NO: 85.

[0220] In some embodiments, the present disclosure teaches methods of producing a plant of the subspecies Beta vulgaris subsp. vulgaris expressing a resistance against Beet Mild Yellowing Virus (BMW), said method comprising the steps of: (a) providing a plant resistant to BMW, (b) crossing the plant of (a) with another plant and harvesting the seed resulting from said cross, (c) growing the seed from step (b). Also, methods comprise submitting the resulting plants for test, diagnosing, and selecting a plant which comprises at least one QTL selected from the group consisting of QTL1, QTL2, QTL3, and QTL4. Optionally, the method comprises (d) continuing the crossing until all QTLs are introgressed, and (e) further propagating or multiplying the resulting variety.

[0221] In some embodiments, the present disclosure teaches methods for reducing yield loss as a consequence of BMW infection, the method comprising the steps of: (a) providing a plant resistant to BMW, a plant identified by the method taught herein, or a plant produced by the method taught herein, or a progeny of thereof having the resistance against BMW, (b) creating seed material, and (c) planting seed in areas which are prone to BMW infection.

[0222] In some embodiments, the present disclosure teaches methods for producing sugar, the method comprising the steps of: (a) growing a plant according to the disclosure and / or a plant identified by the methods taught herein, or a plant produced by the method taught herein, or aprogeny thereof having the having the resistance against BMYV, harvesting the root / beet of said plant, and (b) extracting the sugar from said root / beet of (b). In some embodiments, the growing in step (a) is conducted without the use of insecticides and the sugar extracted from said root / beet is qualified for the organic market.

[0223] In some embodiments, the present disclosure teaches methods of identifying a nucleic acid molecule, which encodes a protein capable of imparting resistance to the pathogen BMYV in a plant of the Beta genus, in which the protein is expressed, characterized in that the method comprises the steps of: (a) detecting at least one polymorphism in the coding nucleotide sequence of the nucleic acid molecule taught herein, using molecular markers, which detect the polymorphism.

[0224] In some embodiments, the present disclosure teaches that resistant varieties having at least one of QTLs taught herein may exhibit some disease symptoms or damage under heavy pest or pathogen pressure. Following an infection by the virus, the viral load in the resistant variety is reduced by at least 5%, by at least 10%, by at least 15%, by at least 20%, by at least 25%, by at least 30%, by at least 35%, by at least 40%, by at least 45%, by at least 50%, by at least 100%, by at least 200%, by at least 30%, when compared to the susceptible variety or the wild type variety without at least one QTL taught herein. The viral load is measured, for example, in an ELISA assay or qPCR.

[0225] In some embodiments, the resistance against yellowing virus(es) is associated with a reduced load of the Beet Mild Yellows Virus by at least 25% in comparison to a variety lacking QTL1, QTL2, QTL3, and QTL4. In some embodiments, the resistance against yellowing virus(es) is associated with a reduced load of the Beet Mild Yellows Virus by at least 50% in comparison to a variety lacking QTL1, QTL2, QTL3, and QTL4. In some embodiments, the resistance against yellowing virus(es) is associated with a reduced load of the Beet Mild Yellows Virus by at least 75% in comparison to a variety lacking QTL1, QTL2, QTL3, and QTL4.

[0226] The present disclosure provides four QTLs on four different chromosomes; on chromosome 1, chromosome 4, chromosome 8, and chromosome 2, conferring tolerance or resistance to BMYV according to the present disclosure. These are heterozygously present in the genome of the plant deposited, and such plant can be used to produce additional BMYV resistant plants by self-crossing or out-crossing.

[0227] In another embodiment, additional desirable traits may be introduced into the resistant or tolerant line. Methods of introducing additional desirable traits may include genetic transformation, genome editing, targeted mutagenesis, traditional breeding, and induced random mutagenesis.

[0228] Traits obtained by genetic transformations include - for example - (i) event H7-1 (OECD ID: KM-000H71-4), which confers resistance against glyphosate, and is described in US7335816, and is commercialized in for example the sugar beet varieties MA902 and HIL9528, (ii) event GTSB77 (OECD ID: SY-GTSB77-8) coding for glyphosate resistance in sugar beet, and (iii) event T120-7 (OECD ID: ACS-BV001-3) coding for glufosinate resistance in sugar beet, described in www.agbios.com / dbase.php# and www.isaaa.org / gmapprovaldatabase / default.asp.

[0229] Traits obtained by induced mutagenesis (mutation breeding) include - for example - tolerance against ALS inhibitor herbicide as described for example in EP3326453A1 (ALS INHIBITOR HERBICIDE TOLERANT BETA VULGARIS MUTANTS), US20210054360A1, and EP2627168A1, and available either from the related patent deposit (NCIMB, Aberdeen, UK, under Number NCIMB 41705) or from multiple commercially available sugar beet varieties including for example SMART RIXTA KWS.

[0230] In some embodiments, the desirable trait is selected from the group consisting of (i) the H7-1 event conferring glyphosate tolerance, (ii) a mutated ALS gene conferring tolerance against ALS herbicides, (iii) the GTSB77 event conferring glyphosate tolerance, and (iv) the T120-7 event conferring glufosinate tolerance. In further embodiments, the ALS gene encodes an ALS polypeptide containing an amino acid different from tryptophan at a position 569 of the ALS polypeptide.DEPOSIT INFORMATION

[0231] A deposit of the sugar beet seed of this disclosure is maintained by DLF Seeds A / S (Ny Oestergade 9, Roskilde 4000, Denmark). In addition, a sample of the beet seed of this disclosure has been deposited with the National Collections of Industrial, Food and Marine Bacteria (NCIMB), 23 St Machar Drive, Aberdeen, Scotland, AB24 3RY, United Kingdom. The seed deposit of the beet cultivar 21000003-71 was made on January 27, 2023.

[0232] To satisfy the enablement requirements of 35 U.S.C. 112, and to certify that the deposit of the present disclosure meets the criteria set forth in 37 C.F.R. 1.801-1.809, Applicantshereby make the following statements regarding deposited beet cultivar 21000003-71 (deposited as NCIMB Accession No. 44107):

[0233] 1. During the pendency of this application, access to the disclosure will be afforded to the Commissioner upon request;

[0234] 2. All restrictions on availability to the public will be irrevocably removed upon granting of the patent under conditions specified in 37 CFR 1.808;

[0235] 3. The deposit will be maintained in a public repository for a period of 30 years or 5 years after the last request or for the effective life of the patent, whichever is longer;

[0236] 4. A test of the viability of the biological material at the time of deposit will be conducted by the public depository under 37 C.F.R. 1.807; and

[0237] 5. The deposit will be replaced if it should ever become unavailable.

[0238] Access to this deposit will be available during the pendency of this application to persons determined by the Commissioner of Patents and Trademarks to be entitled thereto under 37 C.F.R. § 1.14 and 35 U.S.C. § 122. Upon allowance of any claims in this application, all restrictions on the availability to the public of the variety will be irrevocably removed by affording access to a deposit of at least 625 seeds of the same variety with the NCIMB.

[0239] In some embodiments, the QTL associated with tolerance to BMYV described herein are chosen from those present in the genome of sugar beet line 21000003-71, which seeds are deposited under the NCIMB accession number 44107. In some embodiments, the Beta vulgaris subsp. vulgaris plant according to the disclosure is line 21000003-71, which seeds are deposited under NCIMB accession number 44107.

[0240] The present disclosure provides that the deposited beet cultivar 21000003-71 is a uniform Fl hybrid, which is heterozygous for all four QTLs (i.e., QTL1, QTL2, QTL3, and QTL4 taught herein). Beet cultivar 21000003-71 was developed by the introgression of a donor beet variety having four QTLs associated with resistance to BMYV into a susceptible beet variety or a beet variety lacking the QTLs taught herein. Beet cultivar 21000003-71 can be used as breeding material and also commercialized as organic commodity plant products.EXAMPLESExample 1 - Introgression of the trait into susceptible sugar beet germplasm

[0241] Once the genetic determinants had been identified, the resistance germplasm was crossed with a susceptible, high yielding elite germplasm and the resulting Fl was backcrossedwith the same elite germplasm two times to create a back-cross population 2 (BC2). The identified genetic determinants were obtained from a private collection of wild beet, which is proprietarily owned by DLF Seeds A / S and not publicly available. A total of 200 individuals from this BC2 was analyzed using 15 trait specific markers. 10 plants that were heterozygous for the traits were selected and self-crossed to create a BC2S 1 -population that were segregating for all three genetic determinants. A total of 1200 plants were analyzed for the presence of the genetic determinants and one or more plants that were homozygous for the trait were selected. Further self-crossing was conducted until an acceptable level of line homozygosity was achieved and the resulting line is regarded as an output from the introgression program. From each initial cross between the resistant and susceptible germplasm, several outputs were produced and evaluated for resistance.Example 2 - Phenotypic evaluation of virus yellows resistance

[0242] Phenotypic evaluation of resistant material was conducted in two different ways using either semi-field or field trails. For semi-field trials seeds of the test germplasm were sown in greenhouse in 3.5 1 pots. The plants were inoculated in the two-leaf stage with 10 viruliferous Myzus persicae carrying BMYV. The aphids were killed with an insecticide 4 days after inoculation. The plants were then moved outside to a semi-field trial facility when they were in the 6-8 leaf stage. 2-4 reps with 5-10 plants per rep were used for each germplasm. The plants were grown outside normally from May to September and were sprayed with insecticides several times over the growing season to avoid contamination by other aphids.

[0243] For field trials, seeds of the relevant germplasm were sown in field trials with 4 reps and 90 plants per plot. Randomized Complete Block design were used. In each plot a number of the plants were inoculated with 10 viruliferous Myzus persicae carrying BMYV, BChV or BYV when the plants were in the 6-8 leaf stage. The ratio of infected plants is commonly measured in % where for example, 10% refers to one in ten of the available plants that were inoculated with viruliferous aphids. A higher ratio of inoculated plants results in higher overall disease pressure and in faster spread of the disease. The aphids were killed with an insecticide four days after inoculation and the plants were sprayed with insecticides several times over the growing season to avoid contamination by other aphids. The development of symptoms was scored every 3rdweek during the entire season.

[0244] The development of symptoms was scored every 3rdweek during the growing season using a scale from 1-9, with 1 being the worst and 9 being the best. Examples of the scoringcriterias can be seen in FIGs. 1A-1F. Symptom scoring cannot distinguish tolerant from resistant germplasm as neither would show clear symptoms of infection.Example 3- Analysis of virus content

[0245] Enzyme linked immunosorbent assay (ELISA) was used to quantify the virus content of the individual plants. Leaf samples are collected in the tip of the leaves. Leaves of similar age and developing stage were collected for analysis. Sap of 0.3 g of leaf tissue was extracted in 3 ml extraction buffer and analyzed using the recommended protocol from the supplier (DSMZ “QC-SOP-0087 Anl. 002 Double Antibody Sandwich ELISA (DAS-ELISA), Version 2.0” for BYV and “QC-SOP-0087 Anl. 006 Triple Antibody Sandwich ELISA (TAS-ELISA), Version 2.0” for BMYV / BChV). A standard curve based on ground freeze-dried leaf tissue was used on each ELISA plate and used for virus quantification. The highest concentration in the standard curve is 0.15 g freeze dried powder mixed with 3 ml extraction buffer (“100%” in the standard curve ). The standard curve was made in 10 steps and for each step the sample was diluted with buffer 1 : 1 giving the concentrations: 100%, 50%, 25%, 12.5% etc. Polyclonal antibodies for BYV (DSMZ No: AS-0185) and monoclonal antibodies for BMYV and BChV (DSMZ No: RT-0049) supplied by DSMZ (Leibniz Institute DSMZ -German Collection of Microorganisms and Cell Cultures GmbH) in Braunschweig, Germany. The antisera for BMYV and BChV is unable to distinguish between the two poleroviruses BMYV and BChV. To determine which one is present and to test for contaminations, all samples were analyzed using virus-specific qRT-PCR. This was done by sampling leaves in the same manner as described above into RNAlater stabilization solution (ThermoFischer Scientific) and incubated at 4°C for 24 hours. Total RNA extraction was carried out using the PureLink Plant RNA Reagent (ThermoFischer Scientific) in accordance with the manufacturer’s instructions for small scale RNA isolation. The concentration of the RNA was then measured and all samples were diluted to 80 ng / pl before cDNA synthesis was carried out using the iScript cDNA Synthesis kit (BIORAD) following the manufacturer’s instructions. qRT-PCR was then set up and ran using the following program: 95°C for 10 min followed by 95°C for 15 seconds, 54°C for 15 seconds, 72°C for 20 seconds for 40 cycles. Three pairs of virus specific primers were used (Table 2).Table 2Example 4 - Evaluation of resistance of introgressed lines

[0246] Output from several introgression programs was evaluated. Table 3 shows the result of BMYV-infection in semi -field trial conditions on three different elite germplasm before and after the introgression of the resistance trait described above. “LineX (Res)” denotes the introgressed version of “LineX (Sus)” into which all four genetic determinants have been introgressed and fixed in a homozygous form. “Control” is a susceptible line. This shows that it is possible to transfer the resistance trait using the methods described herein and that the resistance is largely independent of the receiving germplasm, although some minor variation is observable which is to be expected.Table 3

[0247] Table 4 shows ELISA %BMYV data for leaves of different ages (“Old”, “Middle” and “Young”) sampled at two different timepoints (TO and 21 days after TO). “Source” is the original resistance source used for the identification of the genetic determinants. “LineX (Res)” denotes the introgressed version of “LineX (Sus)” into which all four genetic determinants have been introgressed using the method described above. For “Line B”, the numbers denote different outputs from the same introgression project. This shows that the introgressed resistance trait is systemic in the plant and stable over time and not significantly influenced by sampling time point.Table 4Example 5 - Creation and evaluation of three-way hybrids

[0248] Three-way hybrids can be created in a number of ways but most commonly a male sterility system is used allowing for large scale production of tightly controlled crosses. Using such a system, the first step is to convert a fertile elite germplasm into a male sterile by transferring the genetic determinants required for the male sterility trait. This male sterile germplasm can then be pollinated by a fully fertile line creating a heterozygous but heterogenous Fl population. If for example a cytosolic male sterility system is used, the male sterility can also be maintained in the Fl. This Fl MS can then easily be pollinated by an additional pollinator to create the final three-way hybrid. Dominant traits can be introduced and maintained in either the female (F 1 MS) side or the male (pollinator) side of the final hybrid while a recessive trait must be fixed in all three components of the final hybrid. A dominant trait is therefore of very high economic value to the breeders. In order to confirm the nature of the trait and evaluate its performance in hybrid form the genetic determinants were introgressed into several pollinator germplasm and combined with several commercially relevant F1MS-mothers. These three-way hybrids were then evaluated in semi-field and field conditions for virus yellows resistance.

[0249] Tables 5 and 6 contains data from semi-field evaluation of three different three-way hybrids showing the results from phenotypic scoring and ELISA-based quantification of virus content for all three viruses. Table 5 covers experiments carried out in year 1 (2021) while Table 6 contains data from year 3 (2023). “Pollinator (Res)” is the resistant pollinator created by introgressing the genetic determinants from “Source” into “Control (Pollinator (Sus))”. F1MS-X is the single hybrid used as the parent for the three-way hybrid. This shows that the resistance achievable by the above described method of introgression is functional in a hybrid and heterozygous form against BMYV and BChV. No data was collected for BYV except for the introgressed pollinator (line level) showing that some resistance / tolerance against BYV is linked to the same genetic determinants. ND = No data.Table 5Table 6(sus): Means a susceptible (non-converted) line / hybrid. res: Means a resistant (converted) line / hybrid.

[0250] The source material (#1) and the converted (resistant) lines (#3) and hybrids (#7, #9) show a clear improvement in phenotype (Score) and a substantial reduction in virus content in comparison to non-resistant / non-tolerant material (#2, #4, #5, #6, #8) but also in comparison to varieties Maruscha (#11) and Yellowstone (#110) which are described to be BMYV -tolerant.

[0251] Results from two different field trials on hybrids conducted in Sweden can be found in Table 7. In this evaluation, two different single hybrids (“F1MS-C” and “F1MS-D”) were used to evaluate the influence of one resistant pollinator (“PollA”) compared with two different susceptible pollinators (“PollB” and “PollC”). As a control, a commercial susceptible hybrid was used. These results show that when used as the pollinator, the three-way hybrid becomes resistant compared to when a susceptible pollinator is used. This is true for all three viruses evaluated.Table 7

[0252] Additional field trials were carried out in Svalof, Sweden in year 2. All entries consisted of three-way hybrids with the commercial hybrids Yellowstone and Maruscha. In Table 8, The F1MS-D is the same female used in Table 6 and Table 9. The term “Source” refers to the source germplasm for the genetic determinants. Pollinators referred to as “(sus)” consist of elite germplasm which does not carry any of the mentioned genetic determinants while “(res)” refers to the corresponding susceptible germplasm to which the genetic determinants required for resistance has been transferred by e.g. introgression.Table 9(sus): Means a susceptible (non-converted) line / hybrid. res: Means a resistant (converted) line / hybrid.

[0253] The resistant hybrids (#1, #3) show a clear improvement in phenotype (Score) and a substantial reduction in virus content in comparison to non-resistant / non-tolerant material (#2) but also in comparison to varieties Maruscha (#5) and Yellowstone (#4) which are described to be BMYV-tolerant.

[0254] Table 10 contains results from yield trials conducted in Svalof, Sweden in year 2 using a 20% infection rate. All entries, with the exceptions from the two controls (Y ellowstone and Maruscha) which are commercially available hybrids, consists of three-way hybrids consisting of the same female (F1MS-D) crossed with a pollinator. The pollinator group DI -D6 represents closely related germplasm where an elite pollinator (DI) with no resistance against BMYV and BYV has undergone the introgression process to transfer the genetic determinants with the resulting outputs (D2-D6) used for hybrid production. Pollinator El and E2 represent a similar setup but with only a single output (E2). The % yield was calculated using the following formula:Where YTP denotes Yield Trial Plot and I refer to inoculated plots.Table 10(sus): Means a susceptible (non-converted) line / hybrid. res: Means a resistant (converted) line / hybrid.

[0255] The resistant hybrids (#1, #3, #4, #5, #6, #7) show an improvement in yield in comparison to non-resistant / non-tolerant material (#2, #8, #9) under the conditions of a moderate (20%) infection challenge.

[0256] The following two tables are data from official trials conducted in Year 2 (2022) by official testing organizations using a 5% infection rate. In Table 11 is shown the relative results from French official testing conducted by CTPS. Four different three-way hybrids were submitted to the trials composed of two different single -hybrids (“F1MS-X”) crossed with three different pollinators, one of which was resistant (“Poll A (Res)”). The plant material was evaluated for root yield (RY, tonnes / hectare) and sugar content (SC, % sugar wet weight).Table 11

[0257] Table 12 shows data from official trials in Belgium Year 2 using a 5% infection rate where field inoculated with BMYV were scored at three different timepoints: 32, 43 and 71 days post inoculation (DPI). Scoring was done by counting number of plants with visible symptoms and them calculating their percentage. The same single hybrid was used as the mother for all three hybrids. This result confirms that the resistant hybrid carrying the trait in a heterozygous form is able to withstand the disease pressure significantly better than the susceptible hybrids.Table 12

[0258] Table 13 contains data from UK COMEX trials in 2023 where a 100% infection rate of all three viruses (BYC, BMYV and BChV) was used and the yield reduction measured.Table 13(sus): Means a susceptible (non-converted) line / hybrid. res: Means a resistant (converted) line / hybrid.

[0259] The resistant hybrids (#3, #4, #5, #6) show an improvement in yield in comparison to non-resistant / non-tolerant material (#1, #2).Example 6 - Introgression of the trait into susceptible sugar beet germplasm

[0260] Introgression of the desired trait into susceptible sugar beet germplasm was conducted in the following manner. A homozygous resistant line (“donor parent”) carrying the four required genetic determinants is crossed with a susceptible line (’’recurrent parent”). A recurrent parent can consist of any susceptible individual belonging to a species crossable with sugar beet such as members of the Beta vulgaris ssp. vulgaris group which includes crops such as sugar beet, chard, beetroot and mangold but also closely related species such as Beta vulgaris ssp. maritima or any other member of the Betoideae family able to produce viable offspring when crossed with Beta vulgaris ssp. vulgaris. The resulting Fl can then be self-crossed to establish an F2 population in which the genetic determinants are segregating. By the application of the informative molecular markers developed in this work individuals that carry one or more of these genetic determinants. This process can then be repeated with additional crosses to resistant germplasm until all three genetic determinants have been assembled and the resistant trait has been introgressed into the selected germplasm.

[0261] Another approach is to backcross the Fl with the recurrent parent. Single plant offspring from this first backcross (BC1) or any additional backcrosses (BCX) can then be selected using the markers developed from the initial mapping population to identify plants carrying the genetic determinants responsible for the trait in a heterozygous or homozygous form. Based on these markers, plants carrying the markers for the trait but otherwise showing high similarity with the receiver line are selected for selfing. These plants can then be selfcrossed to produce a BCXS 1 which will be segregating for the desired trait. By again applying the herein developed markers, plants which carry the trait in either heterozygous or homozygous form can be selected for further breeding and evaluation. A large number of the offspring is then analyzed using the molecular markers described above to determine the inheritance pattern across the genome between the donor and receiver parental genotypes. In this analysis, a number (-100 SNP-markers) are used to trace the parental genomes over a population of around 100 offsprings and identify the individuals carrying the desired regions associated with the traits from the donor parent. Flanking markers for the trait have been developed to allow for the identification of crossovers close to the region of interest. Additional markers (i.e. five) between the two flanking markers are also used to ensure correct introgression. Fewer markers can be used but increase the risk of failed introgression due to unwanted crossovers. Other markers are used to select for crossovers with the receiver germplasm. Based on these markers, plants carrying the markers for the trait but otherwise showing high similarity with the receiver line are selected for selfing. At this stage, only heterozygous trait specific markers are selected.Example 7 - Application of marker technology to select for the trait

[0262] Once a susceptible germplasm has been crossed with a resistant germplasm carrying the required genetic determinants described above, the resulting heterozygous offspring, commonly called Fl, can be used to create a segregating population by additional crossing using any suitable germplasm, including self-crossing. From such a segregating population, commonly called F2, homozygous resistant germplasm can be extracted by using the described molecular markers. For this, plants from the segregating population are analyzed for the presence of the resistant alleles and the plants carrying all the correct alleles are selected as resistant. The fixation of all genetic determinants can be done stepwise by repeated crosses. For the purpose of marker selection, both the confidence interval (usually 95%) or the single point best likelihood model can be utilized.Example 8 - Description on KASP marker technology

[0263] KASP genotyping is based on competitive allele-specific PCR and is within this application used to distinguish germplasm carrying the relevant genetic determinants in a bi- allelic manner. The KASP-technology requires two allele-specific forward primers and one common reverse primer. Each allele-specific primer carries a FRET (Forster resonance energy transfer) cassette labeled with either the FAM or HEX dye. Before thermal cycling, the FRET cassettes are associated through sequence homology with a quencher molecule. Once the newly synthesized template is available, the quencher carrying sequence will dissociate allowing the FRET cassette allowing the fluorophores (HEX and FAM) to emit light within their respective emission range. These signals can then be measured for each sample and if only one of the signals are present, the sample will be interpreted as being homozygous forthat specific allele. If both signals are present, the sample is heterozygous. The technology is therefore able to reliably detect heterozygous germplasm. An overview of the KASP-markers designed to assess the virus yellows resistance trait can be found in Table 14.Table 14

[0264] SEQ ID NO: 1-45, and SEQ ID NO: 52 to SEQ ID NO: 87 are primer sequences used for KASP / marker analysis of the trait. Three primers are needed for the marker system to work (e.g., SEQ ID NO: 1-3). For example, for QTL1, SEQ ID NO: 1 is the forward primer for the susceptible allele at that position, SEQ ID NO:2 is the forward primer for the resistant allele and SEQ ID NO:3 is the common reverse primer for both forward primers. In a KASP-assay, all three primers would be mixed, but theoretically, only the primer for the resistant allele is required to detect the SNP of interest. If only one primer is used, heterozygous alleles are not able to be detected (the assay becomes dominant).

[0265] SEQ ID NO:46-SEQ ID NO:51 are primers used in qRT-PCR verification ofthe viruses and are also presented in Table 2. SEQ ID NO:46 and SEQ ID NO:47 are specific for BMYV, SEQ ID NO:48 and SEQ ID NO:49 are specific for BChV and SEQ ID NO:50 and SEQ ID NO:51 are specific for BYV. The PCR condition is described in Table 15 and the primer sequence information in Table 16.Table 15Table 16Example 9 - Resistant lines disclosed herein exhibit significantly reduced viral load compared to lines lacking OTLl, QTL2, QTL3, and QTL4

[0266] The varieties provided by KWS provide a certain tolerance against yellowing viruses, which mitigates some of the effects to some extent and provides a certain “stay green” effect under virus pressure. However, no substantial reduction of virus load can be seen from Marushca KWS when compared to a hybrid of the present disclosure containing three QTLs (i.e., QTL1, QTL2, QTL3, and QTL4), as presented in Table 17. The value shown in Table 17 is the average ELISA-results of 8 plants from semi-field trials to test resistance to yellowing viruses (BMYV, BYV, and BChV). The susceptible hybrid plants as a control show no resistance to yellowing viruses and a full viral load. While Maruscha KWS plants show mild tolerance to yellowing viruses with no significant reduction of viral load (about 20%), the resistant hybrid plants possessing three QTLs of the present disclosure present strong resistancewith significant reduction of viral road (about 66% to about 99%), which is at least about 3 times higher resistance than the Maruscha KWS.Table 17INCORPORATION BY REFERENCE

[0267] All references, articles, publications, patents, patent publications, and patent applications cited herein are incorporated by reference in their entireties for all purposes. However, mention of any reference, article, publication, patent, patent publication, and patent application cited herein is not, and should not be taken as an acknowledgment or any form of suggestion that they constitute valid prior art or form part of the common general knowledge in any country in the world.

[0268] It should be understood that the above description is only representative of illustrative embodiments and examples. For the convenience of the reader, the above description has focused on a limited number of representative examples of all possible embodiments, examples that teach the principles of the disclosure. The description has not attempted to exhaustively enumerate all possible variations or even combinations of those variations described. That alternate embodiments may not have been presented for a specific portion of the disclosure, or that further undescribed alternate embodiments may be available for a portion, is not to be considered a disclaimer of those alternate embodiments. One of ordinary skill will appreciate that many of those undescribed embodiments, involve differences in technology and materials rather than differences in the application of the principles of the disclosure. Accordingly, the disclosure is not intended to be limited to less than the scope set forth in the following claims and equivalents.NUMBERED EMBODIMENTS OF THE DISCLOSURE

[0269] Notwithstanding the appended claims, the disclosure sets forth the following numbered embodiments:Beta vulgaris subsp. vulgaris plant, plant part, or plant cell resistant to Beet Mild Yellowing Virus (BMYV)1. A Beta vulgaris subsp. vulgaris plant, plant part, or plant cell resistant to Beet Mild Yellowing Virus (BMYV), wherein said plant, plant part, or plant cell comprises at least one Quantitative Trait Loci (QTL) associated with resistance to BMYV, wherein said QTL is selected from the group consisting of QTL1, QTL2, and QTL3, and wherein QTL1, QTL2, and QTL 3, are obtainable from Beta vulgaris subsp. vulgaris line 21000003-71, representative seed of which has been deposited under NCIMB number 44107.2. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of embodiment 1, wherein QTL1 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV504245, PBV125552, PBV291217, PBV369685, and PBV261963, wherein:PBV504245 is a C to G substitution corresponding to position 1050427 of chromosome1 of the Refbeet 1.5 reference genome,PBV125552 is a G to A substitution corresponding to position 3069972 of chromosome1 of the Refbeet 1.5 reference genome,PBV291217 is a G to A substitution corresponding to position 4315236 of chromosome1 of the Refbeet 1.5 reference genome,PBV369685 is an A to G substitution corresponding to position 4330737 of chromosome 1 of the Refbeet 1.5 reference genome, andPBV261963 is an A to T substitution corresponding to position 4356001 of chromosome 1 of the Refbeet 1.5 reference genome,3. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of embodiment 1 or 2, wherein QTL1 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV757437, PBV638722, and EPBV6296, wherein:PBV757437 is a G to A substitution corresponding to position 17043 of chromosome 1 of the Refbeet 1.5 reference genome,PBV638722 is an A to G substitution corresponding to position 2645728 of chromosome1 of the Refbeet 1.5 reference genome, andEPBV6296 is a T to C substitution corresponding to position 1117040 of chromosome 1 of the Refbeet 1.5 reference genome.4. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of embodiment 1, wherein QTL2 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV577030, PBV562771, PBV573138, PBV273480, and PBV821051, wherein:PBV577030 is an A to G substitution corresponding to position 5742753 of chromosome 4 of the Refbeet 1.5 reference genome,PBV562771 is a G to A substitution corresponding to position 9767085 of chromosome4 of the Refbeet 1.5 reference genome,PBV573138 is an A to G substitution corresponding to position 10271308 of chromosome 4 of the Refbeet 1.5 reference genome,PBV273480 is a G to A substitution corresponding to position 46718199 of chromosome 4 of the Refbeet 1.5 reference genome, andPBV821051 is a G to A substitution corresponding to position 47855576 of chromosome 4 of the Refbeet 1.5 reference genome.5. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of embodiment 1, wherein QTL3 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV148969, PBV331644, PBV882826, PBV374371, and PBV757436, wherein:PBV148969 is an A to G substitution corresponding to position 436005 of chromosome8 of the Refbeet 1.5 reference genome,PBV331644 is a G to A substitution corresponding to position 1366650 of chromosome8 of the Refbeet 1.5 reference genome,PBV882826 is an A to G substitution corresponding to position 7979633 of chromosome 8 of the Refbeet 1.5 reference genome,PBV374371 is a G to A substitution corresponding to position 8822544 of chromosome8 of the Refbeet 1.5 reference genome, andPBV757436 is an A to C substitution corresponding to position 25201555 of chromosome 8 of the Refbeet 1.5 reference genome.6. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of embodiment 1 or 5, wherein QTL3 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV738292, PBV738293, and EPBV7349, wherein:PBV738292 is a G to an A substitution corresponding to position 35831 of chromosome8 of the Refbeet 1.5 reference genome,PBV738293 is an A to G substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, andEPBV7349 is an A to C substitution corresponding to position 275340 of chromosome8 of the Refbeet 1.5 reference genome,7. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of any one of embodiments 1-6, further comprising a fourth QTL (QTL4) associated with resistance to BMYV, wherein QTL4 is genetically linked to at least one marker loci selected from the group consisting of GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821, wherein:GRKPBV98281 is a G to A substitution corresponding to position 8040503 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV627372 is a C to an A substitution corresponding to position 9433027 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV672273 is a G to an A substitution corresponding to position 12212298 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV627178 is an A to C substitution corresponding to position 18410288 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV116271 is an A to C substitution corresponding to position 20007280 of chromosome 2 of the Refbeet 1.5 reference genome, and wherein QTL4 is obtainable from Beta vulgaris subsp. vulgaris line 21000003-71, representative seed of which has been deposited under NCIMB number 44107.8. The plant, plant part, or plant cell of any one of embodiments 1-7, wherein the resistance is associated with a reduced load of the Beet Mild Yellows Virus by at least 25% in comparison to a variety lacking QTL1, QTL2, QTL3, and / or QTL4.9. The plant, plant part, or plant cell of any one of embodiments 1-7, wherein the resistance is associated with a reduced load of the Beet Mild Yellows Virus by at least 50% in comparison to a variety lacking QTL1, QTL2, QTL3, and / or QTL4.10. The plant, plant part, or plant cell of any one of embodiments 1-7, wherein the resistance is associated with a reduced load of the Beet Mild Yellows Virus by at least 75% in comparison to a variety lacking QTL1, QTL2, QTL3, and / or QTL4.11. The plant, plant part, or plant cell of any one of embodiments 8- 10, wherein the reduced load of the Beet Mild Yellows Virus is determined by an antibody assay.12. The plant, plant part, or plant cell of embodiment 11, wherein the antibody assay is an enzyme-linked immunosorbent assay.13. The plant, plant part, or plant cell of any one of embodiments 8-12, wherein the reduced load of the Beet Mild Yellows Virus is determined by an antibody assay in comparison to a plant, plant part, or plant cell which is genetically essentially identical except for the presence of the resistance to BMYV.14. The plant, plant part, or plant cell of any of embodiments 1-13, wherein said plant, plant part, or plant cell is also resistant against Beet yellows virus (BYV) or Beet chlorosis virus (BChV).15. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for at least one of QTL1, QTL2, QTL3, and QTL4.16. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL1 and QTL2.17. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL1 and QTL3.18. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL1 and QTL4.19. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL2 and QTL3.20. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL2 and QTL4.21. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL3 and QTL4.22. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL1, QTL2, QTL3, and QTL4.23. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for at least one of QTL1, QTL2, QTL3, and QTL4.24. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL1 and QTL2.25. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL1 and QTL3.26. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL3 and QTL4.27. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL2 and QTL3.28. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL2 and QTL4.29. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL3 and QTL4.30. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL1, QTL2, QTL3, and QTL4.31. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL1, and homozygous for at least one of QTL2, QTL3, and QTL4.32. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL2, and homozygous for at least one of QTL1, QTL3, and QTL4.33. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL3, and homozygous for at least one of QTL1, QTL2, and QTL4.34. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is heterozygous for QTL4, and homozygous for at least one of QTL1, QTL2, and QTL3.35. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL1, and heterozygous for at least one of QTL2, QTL3, and QTL4.36. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL2, and heterozygous for at least one of QTL1, QTL3, and QTL4.37. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL3, and heterozygous for at least one of QTL1, QTL2, and QTL4.38. The plant, plant part, or plant cell of any of embodiments 1 to 14, wherein said plant, plant part, or plant cell is homozygous for QTL4, and heterozygous for at least one of QTL1, QTL2, and QTL3.39. The plant, plant part, or plant cell of any of embodiments 1 to 38, wherein said plant is a fodder beet or sugar beet.40. The plant, plant part, or plant cell of any one of embodiments 1 to 39, wherein said plant, plant part, or plant cell comprises a desirable trait introduced by a method selected from the group consisting of genetic transformation, genome editing, targeted mutagenesis, and induced random mutagenesis.41. The plant, plant part, or plant cell of embodiment 40, wherein said desirable trait is selected from the group consisting of (i) the H7-1 event conferring glyphosate tolerance, (ii) amutated ALS gene conferring tolerance against ALS herbicides, (iii) the GTSB77 event conferring glyphosate tolerance, and (iv) the T 120-7 event conferring glufosinate tolerance.42. The plant, plant part, or plant cell of embodiment 41, wherein the ALS gene encodes an ALS polypeptide containing an amino acid different from tryptophan at a position 569 of the ALS polypeptide.43. The plant, plant part, or plant cell of any one of embodiments 1-42, further comprising a Beet Mild Yellowing Virus tolerance trait obtainable from the group of sugar beet varieties comprising Maruscha KWS and Novalina KWS.44. A plant part of any one of embodiments 1-43, wherein the plant part is a seed.45. The plant part of embodiment 44, wherein said seed is technically treated, whereby the technical treatment is selected from the group consisting of polishing, pelleting, incrustation, and coloring.46. The plant part of embodiment 45, wherein the technical treatment does not include insecticide.47. A plant part of any one of embodiments 1-46, wherein the plant part is a commodity plant product.48. The commodity plant product of embodiment 47, wherein the plant product is a beet.A marker for selection of Beet Mild Yellowing Virus resistant plants49. A marker for selection of Beet Mild Yellowing Virus resistant plants selected from the group consisting of SEQ ID NO: 1 to SEQ ID NO: 45.50. A marker for selection of Beet Mild Yellowing Virus resistant plants selected from the group consisting of SEQ ID NO: 52 to SEQ ID NO: 87.51. The marker of embodiment 49, wherein the marker utilizes a sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 29, SEQ ID NO: 32, SEQ ID NO: 35, SEQ ID NO: 38, SEQ ID NO: 41, and SEQ ID NO: 44.52. The marker of embodiment 50, wherein the marker utilizes a sequence selected from the group consisting of SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 58, SEQ ID NO: 62, SEQ ID NO: 65, SEQ ID NO: 67, SEQ ID NO: 70, SEQ ID NO: 73, SEQ ID NO: 76, SEQ ID NO: 79, SEQ ID NO: 83, and SEQ ID NO: 85.53. A method of using any one of the molecular markers in embodiment 49 for selection of a plant resistant against a virus selected from the group consisting of Beet Mild Yellowing Virus (BMYV), Beet yellows virus (BYV), and Beet chlorosis virus (BChV).54. A method of using any one of the molecular markers in embodiment 50 for selection of a plant resistant against a virus selected from the group consisting of Beet Mild Yellowing Virus (BMYV), Beet yellows virus (BYV), and Beet chlorosis virus (BChV).55. The method embodiment 53, wherein said molecular markers identify at least one of the Single Nucleotide Polymorphisms present in PBV504245, PBV125552, PBV291217, PBV369685, PBV261963, PBV577030, PBV562771, PBV573138, PBV273480, PBV821051, PBV148969, PBV331644, PBV882826, PBV374371, and PBV757436.56. The method embodiment 54, wherein said molecular markers identify at least one of the Single Nucleotide Polymorphisms present in PBV757437, PBV638722, EPBV6296, PBV738292, PBV738293, EPBV7349, GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821.Methods of identifying a plant, plant part, or plant cell comprising at least one of a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV)57. A method of identifying a plant, plant part, or plant cell comprising a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 1 (QTL1), said method comprising the steps of: screening for the presence of QTL1, wherein QTL1 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV504245, PBV125552, PBV291217, PBV369685, and PBV261963, wherein:PBV504245 is a C to G substitution corresponding to position 1050427 of chromosome 1 of the Refbeet 1.5 reference genome,PBV125552 is a G to A substitution corresponding to position 3069972 of chromosome 1 of the Refbeet 1.5 reference genome,PBV291217 is a G to A substitution corresponding to position 4315236 of chromosome 1 of the Refbeet 1.5 reference genome,PBV369685 is an A to G substitution corresponding to position 4330737 of chromosome 1 of the Refbeet 1.5 reference genome, andPBV261963 is an A to T substitution corresponding to position 4356001 of chromosome 1 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL1.58. The method of embodiment 57, wherein said screening for the presence of QTL1 further comprises identifying a plant, plant part, or plant cell having at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV757437, PBV638722, and EPBV6296, wherein:PBV757437 is a G to A substitution corresponding to position 17043 of chromosome 1 of the Refbeet 1.5 reference genome,PBV638722 is an A to G substitution corresponding to position 2645728 of chromosome 1 of the Refbeet 1.5 reference genome, andEPBV6296 is a T to C substitution corresponding to position 1117040 of chromosome 1 of the Refbeet 1.5 reference genome.59. A method of identifying a plant, plant part, or plant cell comprising a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 4 (QTL2), said method comprising the steps of: screening for the presence of QTL2, wherein QTL2 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV577030, PBV562771, PBV573138, PBV273480, and PBV821051, wherein:PBV577030 is an A to G substitution corresponding to position 5742753 of chromosome 4 of the Refbeet 1.5 reference genome,PBV562771 is a G to A substitution corresponding to position 9767085 of chromosome 4 of the Refbeet 1.5 reference genome,PBV573138 is an A to G substitution corresponding to position 10271308 of chromosome 4 of the Refbeet 1.5 reference genome,PBV273480 is a G to A substitution corresponding to position 46718199 of chromosome 4 of the Refbeet 1.5 reference genome, andPBV821051 is a G to A substitution corresponding to position 47855576 of chromosome 4 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL2.60. A method of identifying a plant, plant part, or plant cell comprising a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 8 (QTL3), said method comprising the steps of: screening for the presence of QTL3, wherein QTL3 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV148969, PBV331644, PBV882826, PBV374371, and PBV757436, wherein:PBV148969 is an A to G substitution corresponding to position 436005 of chromosome 8 of the Refbeet 1.5 reference genome,PBV331644 is a G to A substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome,PBV882826 is an A to G substitution corresponding to position 7979633 of chromosome 8 of the Refbeet 1.5 reference genome,PBV374371 is a G to A substitution corresponding to position 8822544 of chromosome 8 of the Refbeet 1.5 reference genome, andPBV757436 is an A to C substitution corresponding to position 25201555 of chromosome 8 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL3.61. The method of embodiment 60, wherein said screening for the presence of QTL3 further comprises identifying a plant, plant part, or plant cell having at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV738292, PBV738293, and EPBV7349, wherein:PBV738292 is a G to an A substitution corresponding to position 35831 of chromosome 8 of the Refbeet 1.5 reference genome,PBV738293 is an A to G substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, andEPBV7349 is an A to C substitution corresponding to position 275340 of chromosome 8 of the Refbeet 1.5 reference genome.62. A method of identifying a plant, plant part, or plant cell comprising a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 2 (QTL4), said method comprising the steps of: screening for the presence of QTL4, wherein QTL4 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821, wherein:GRKPBV98281 is a G to A substitution corresponding to position 8040503 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV627372 is a C to an A substitution corresponding to position 9433027 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV672273 is a G to an A substitution corresponding to position 12212298 of chromosome 2 of the Refbeet 1.5 reference genome, GRKPBV627178 is an Ato C substitution corresponding to position 18410288 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV 116271 is an Ato C substitution corresponding to position 20007280 of chromosome 2 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL4.63. The method of embodiment 57, wherein the screening for the presence of QTL1 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 2 and SEQ ID NO: 3,PCR amplification of DNA with SEQ ID NO: 5 and SEQ ID NO: 6,PCR amplification of DNA with SEQ ID NO: 8 and SEQ ID NO: 9,PCR amplification of DNA with SEQ ID NO: 11 and SEQ ID NO: 12, andPCR amplification of DNA with SEQ ID NO: 14 and SEQ ID NO: 15.64. The method of embodiment 58, wherein the screening for the presence of QTL1 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 52 and SEQ ID NO: 54,PCR amplification of DNA with SEQ ID NO: 56 and SEQ ID NO: 57, andPCR amplification of DNA with SEQ ID NO: 58 and SEQ ID NO: 60.65. The method of embodiment 59, wherein the screening for the presence of QTL2 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 17 and SEQ ID NO: 18,PCR amplification of DNA with SEQ ID NO: 20 and SEQ ID NO: 21,PCR amplification of DNA with SEQ ID NO: 23 and SEQ ID NO: 24,PCR amplification of DNA with SEQ ID NO: 26 and SEQ ID NO: 27, andPCR amplification of DNA with SEQ ID NO: 29 and SEQ ID NO: 30.66. The method of embodiment 60, wherein the screening for the presence of QTL3 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 32 and SEQ ID NO: 33,PCR amplification of DNA with SEQ ID NO: 35 and SEQ ID NO: 36,PCR amplification of DNA with SEQ ID NO: 38 and SEQ ID NO: 39,PCR amplification of DNA with SEQ ID NO: 41 and SEQ ID NO: 42, and PCR amplification of DNA with SEQ ID NO: 44 and SEQ ID NO: 45.67. The method of embodiment 61, wherein the screening for the presence of QTL3 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 62 and SEQ ID NO: 63PCR amplification of DNA with SEQ ID NO: 65 and SEQ ID NO: 66, andPCR amplification of DNA with SEQ ID NO: 67 and SEQ ID NO: 69.68. The method of embodiment 62, wherein the screening for the presence of QTL4 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 70 and SEQ ID NO: 72,PCR amplification of DNA with SEQ ID NO: 73 and SEQ ID NO: 75,PCR amplification of DNA with SEQ ID NO: 76 and SEQ ID NO: 78,PCR amplification of DNA with SEQ ID NO: 79 and SEQ ID NO: 81,PCR amplification of DNA with SEQ ID NO: 83 and SEQ ID NO: 84, andPCR amplification of DNA with SEQ ID NO: 85 and SEQ ID NO: 87.Methods of producing a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell having resistance to Beet Mild Yellowing Virus (BMYV)69. A method of producing a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell having resistance to Beet Mild Yellowing Virus (BMYV), said method comprising the steps of:(a) providing a plant having resistance to Beet Mild Yellowing Virus (BMYV);(b) crossing the plant of (a) with another plant and harvesting the seed resulting from said cross;(c) growing the seed from step (b) to produce a progeny plant, and submitting the progeny plant to the method of identifying a plant comprising at least one of a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV); and(d) selecting a progeny plant which comprises at least one of QTL1, QTL2, and QTL3.70. The method of embodiment 69, wherein selecting further comprises selecting a progeny plant having QTL4.71. The method of any one of embodiments 69-72, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 2 and SEQ ID NO: 3,PCR amplification of DNA with SEQ ID NO: 5 and SEQ ID NO: 6,PCR amplification of DNA with SEQ ID NO: 8 and SEQ ID NO: 9, PCR amplification of DNA with SEQ ID NO: 11 and SEQ ID NO: 12, and PCR amplification of DNA with SEQ ID NO: 14 and SEQ ID NO: 15.72. The method of any one of embodiments 69-73, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 52 and SEQ ID NO: 54, PCR amplification of DNA with SEQ ID NO: 56 and SEQ ID NO: 57, and PCR amplification of DNA with SEQ ID NO: 58 and SEQ ID NO: 60.73. The method of any one of embodiments 69-74, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 17 and SEQ ID NO: 18, PCR amplification of DNA with SEQ ID NO: 20 and SEQ ID NO: 21, PCR amplification of DNA with SEQ ID NO: 23 and SEQ ID NO: 24, PCR amplification of DNA with SEQ ID NO: 26 and SEQ ID NO: 27, and PCR amplification of DNA with SEQ ID NO: 29 and SEQ ID NO: 30.74. The method of any one of embodiments 69-75, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 32 and SEQ ID NO: 33, PCR amplification of DNA with SEQ ID NO: 35 and SEQ ID NO: 36, PCR amplification of DNA with SEQ ID NO: 38 and SEQ ID NO: 39, PCR amplification of DNA with SEQ ID NO: 41 and SEQ ID NO: 42, and PCR amplification of DNA with SEQ ID NO: 44 and SEQ ID NO: 45.75. The method of any one of embodiments 69-76, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 62 and SEQ ID NO: 63PCR amplification of DNA with SEQ ID NO: 65 and SEQ ID NO: 66, andPCR amplification of DNA with SEQ ID NO: 67 and SEQ ID NO: 69.76. The method of any one of embodiments 69-77, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 70 and SEQ ID NO: 72, PCR amplification of DNA with SEQ ID NO: 73 and SEQ ID NO: 75, PCR amplification of DNA with SEQ ID NO: 76 and SEQ ID NO: 78, PCR amplification of DNA with SEQ ID NO: 79 and SEQ ID NO: 81, PCR amplification of DNA with SEQ ID NO: 83 and SEQ ID NO: 84, andPCR amplification of DNA with SEQ ID NO: 85 and SEQ ID NO: 87.77. The method of any one of embodiments 69-76, further comprising(e) backcrossing said selected progeny plant to a parental line to produce a backcross progeny having two or more QTLs associated with resistance to Beet Mild Yellowing Virus.78. The method of any one of embodiments 69-77, further comprising(e) backcrossing said selected progeny plant to a parental line to produce backcross progeny having a desirable trait and resistance to Beet Mild Yellowing Virus.79. The method of any one of embodiments 69 to 78, further comprising introducing or introgressing a desirable trait introduced by a method selected from the group consisting of genetic transformation, genome editing, targeted mutagenesis, and induced random mutagenesis.80. The method of embodiment 78 or 79, wherein said desirable trait is selected from the group consisting of (i) the H7-1 event conferring glyphosate tolerance, (ii) a mutated Acetolactate Synthase (ALS) gene conferring tolerance against ALS herbicides, (iii) the GTSB77 event conferring glyphosate tolerance, and (iv) the T120-7 event conferring glufosinate tolerance.81. The method of embodiment 80, wherein the ALS gene encodes an ALS polypeptide containing an amino acid different from tryptophan at a position 569 of the ALS polypeptide.82. The method of any of embodiments 69-81, further comprising introgressing a Beet Mild Yellowing Virus tolerance trait obtainable from the group of sugar beet varieties comprising Maruscha KWS and Novalina KWS.83. The method of any one of embodiments 69-82, wherein the selected progeny plant or backcross progeny plant is selfed or asexually propagated.Methods of reducing yield loss as a consequence of Beet Mild Yellowing Virus (BMYV) infection84. A method for reducing yield loss as a consequence of Beet Mild Yellowing Virus (BMYV) infection, the method comprising the steps of:(a) providing a seed for a plant having resistance to Beet Mild Yellowing Virus (BMYV), a plant identified by the method of any one of embodiments 57-68, or a plant produced by the method of any one of embodiments 69-83; and(b) planting said seed in areas which are prone to Beet Mild Yellowing Virus infection.85. The method of embodiment 84, wherein the seed is planted in areas where the use of insecticides to control the vector for Beet Mild Yellowing Virus transmission is restricted, prohibited, or not desired.Methods of for producing sugar86. A method for producing sugar, the method comprising the steps of:(a) growing the plant having resistance to Beet Mild Yellowing Virus (BMYV), a plant identified by the method of any one of embodiments 57-68, or a plant produced by the method of any one of embodiments 69-83;(b) harvesting the root / beet of said plant, and(c) extracting the sugar from said root / beet of (b).87. The method of embodiment 86, wherein the growing is conducted without the use of insecticides and the sugar extracted from said root / beet is qualified for the organic market.

Claims

WHAT IS CLAIMED IS:

1. A Beta vulgaris subsp. vulgaris plant, plant part, or plant cell resistant to Beet Mild Yellowing Virus (BMYV), wherein said plant, plant part, or plant cell comprises at least one Quantitative Trait Loci (QTL) associated with resistance to BMYV, wherein said QTL is selected from the group consisting of QTL1, QTL2, and QTL3, and wherein QTL1, QTL2, and QTL 3, are obtainable from Beta vulgaris subsp. vulgaris line 21000003-71, representative seed of which has been deposited under NCIMB number 44107.

2. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of claim 1, wherein QTL1 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV504245, PBV125552, PBV291217, PBV369685, and PBV261963, wherein:PBV504245 is a C to G substitution corresponding to position 1050427 of chromosome1 of the Refbeet 1.5 reference genome,PBV125552 is a G to A substitution corresponding to position 3069972 of chromosome1 of the Refbeet 1.5 reference genome,PBV291217 is a G to A substitution corresponding to position 4315236 of chromosome1 of the Refbeet 1.5 reference genome,PBV369685 is an A to G substitution corresponding to position 4330737 of chromosome 1 of the Refbeet 1.5 reference genome, andPBV261963 is an A to T substitution corresponding to position 4356001 of chromosome 1 of the Refbeet 1.5 reference genome,3. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of claim 1, wherein QTL1 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV757437, PBV638722, and EPBV6296, wherein:PBV757437 is a G to A substitution corresponding to position 17043 of chromosome 1 of the Refbeet 1.5 reference genome,PBV638722 is an A to G substitution corresponding to position 2645728 of chromosome1 of the Refbeet 1.5 reference genome, andEPBV6296 is a T to C substitution corresponding to position 1117040 of chromosome 1 of the Refbeet 1.5 reference genome.

4. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of claim 1, wherein QTL2 is genetically linked to at least one single nucleotide polymorphism (SNP) selected fromthe group consisting ofPBV577030, PBV562771, PBV573138, PBV273480, and PBV821051, wherein:PBV577030 is an A to G substitution corresponding to position 5742753 of chromosome 4 of the Refbeet 1.5 reference genome,PBV562771 is a G to A substitution corresponding to position 9767085 of chromosome4 of the Refbeet 1.5 reference genome,PBV573138 is an A to G substitution corresponding to position 10271308 of chromosome 4 of the Refbeet 1.5 reference genome,PBV273480 is a G to A substitution corresponding to position 46718199 of chromosome 4 of the Refbeet 1.5 reference genome, andPBV821051 is a G to A substitution corresponding to position 47855576 of chromosome 4 of the Refbeet 1.5 reference genome.

5. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of claim 1, wherein QTL3 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV148969, PBV331644, PBV882826, PBV374371, and PBV757436, wherein:PBV148969 is an A to G substitution corresponding to position 436005 of chromosome8 of the Refbeet 1.5 reference genome,PBV331644 is a G to A substitution corresponding to position 1366650 of chromosome8 of the Refbeet 1.5 reference genome,PBV882826 is an A to G substitution corresponding to position 7979633 of chromosome 8 of the Refbeet 1.5 reference genome,PBV374371 is a G to A substitution corresponding to position 8822544 of chromosome8 of the Refbeet 1.5 reference genome, andPBV757436 is an A to C substitution corresponding to position 25201555 of chromosome 8 of the Refbeet 1.5 reference genome.

6. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of claim 1, wherein QTL3 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV738292, PBV738293, and EPBV7349, wherein:PBV738292 is a G to an A substitution corresponding to position 35831 of chromosome8 of the Refbeet 1.5 reference genome,PBV738293 is an A to G substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, andEPBV7349 is an A to C substitution corresponding to position 275340 of chromosome8 of the Refbeet 1.5 reference genome,7. The Beta vulgaris subsp. vulgaris plant, plant part, or plant cell of claim 1, further comprising a fourth QTL (QTL4) associated with resistance to BMYV, wherein QTL4 is genetically linked to at least one marker loci selected from the group consisting of GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821, wherein:GRKPBV98281 is a G to A substitution corresponding to position 8040503 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV627372 is a C to an A substitution corresponding to position 9433027 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV672273 is a G to an A substitution corresponding to position 12212298 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV627178 is an A to C substitution corresponding to position 18410288 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV116271 is an A to C substitution corresponding to position 20007280 of chromosome 2 of the Refbeet 1.5 reference genome, and wherein QTL4 is obtainable from Beta vulgaris subsp. vulgaris line 21000003-71, representative seed of which has been deposited under NCIMB number 44107.

8. The plant, plant part, or plant cell of claim 1, wherein the resistance is associated with a reduced load of the Beet Mild Yellows Virus by at least 25% in comparison to a variety lacking QTL1, QTL2, QTL3, and / or QTL4.

9. The plant, plant part, or plant cell of claim 1, wherein the resistance is associated with a reduced load of the Beet Mild Yellows Virus by at least 50% in comparison to a variety lacking QTL1, QTL2, QTL3, and / or QTL4.

10. The plant, plant part, or plant cell of claim 1, wherein the resistance is associated with a reduced load of the Beet Mild Yellows Virus by at least 75% in comparison to a variety lacking QTL1, QTL2, QTL3, and / or QTL4.

11. The plant, plant part, or plant cell of claim 8, wherein the reduced load of the Beet Mild Yellows Virus is determined by an antibody assay.

12. The plant, plant part, or plant cell of claim 11 , wherein the antibody assay is an enzyme- linked immunosorbent assay.

13. The plant, plant part, or plant cell of claim 8, wherein the reduced load of the Beet Mild Yellows Virus is determined by an antibody assay in comparison to a plant, plant part, or plantcell which is genetically essentially identical except for the presence of the resistance to BMYV.

14. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is also resistant against Beet yellows virus (BYV) or Beet chlorosis virus (BChV).

15. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for at least one of QTL1, QTL2, QTL3, and QTL4.

16. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL1 and QTL2.

17. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL1 and QTL3.

18. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL1 and QTL4.

19. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL2 and QTL3.

20. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL2 and QTL4.

21. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL3 and QTL4.

22. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL1, QTL2, QTL3, and QTL4.

23. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for at least one of QTL1, QTL2, QTL3, and QTL4.

24. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL1 and QTL2.

25. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL1 and QTL3.

26. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL3 and QTL4.

27. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL2 and QTL3.

28. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL2 and QTL4.

29. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL3 and QTL4.

30. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL1, QTL2, QTL3, and QTL4.

31. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL1, and homozygous for at least one of QTL2, QTL3, and QTL4.

32. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL2, and homozygous for at least one of QTL1, QTL3, and QTL4.

33. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL3, and homozygous for at least one of QTL1, QTL2, and QTL4.

34. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is heterozygous for QTL4, and homozygous for at least one of QTL1, QTL2, and QTL3.

35. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL1, and heterozygous for at least one of QTL2, QTL3, and QTL4.

36. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL2, and heterozygous for at least one of QTL1, QTL3, and QTL4.

37. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL3, and heterozygous for at least one of QTL1, QTL2, and QTL4.

38. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell is homozygous for QTL4, and heterozygous for at least one of QTL1, QTL2, and QTL3.

39. The plant, plant part, or plant cell of claim 1 , wherein said plant is a fodder beet or sugar beet.

40. The plant, plant part, or plant cell of claim 1, wherein said plant, plant part, or plant cell comprises a desirable trait introduced by a method selected from the group consisting of genetic transformation, genome editing, targeted mutagenesis, and induced random mutagenesis.

41. The plant, plant part, or plant cell of claim 40, wherein said desirable trait is selected from the group consisting of (i) the H7-1 event conferring glyphosate tolerance, (ii) a mutated ALS gene conferring tolerance against ALS herbicides, (iii) the GTSB77 event conferring glyphosate tolerance, and (iv) the T 120-7 event conferring glufosinate tolerance.

42. The plant, plant part, or plant cell of claim 41, wherein the ALS gene encodes an ALS polypeptide containing an amino acid different from tryptophan at a position 569 of the ALS polypeptide.

43. The plant, plant part, or plant cell of claim 1 , further comprising a Beet Mild Y ellowing Virus tolerance trait obtainable from the group of sugar beet varieties comprising Maruscha KWS and Novalina KWS.

44. A plant part of claim 1, wherein the plant part is a seed.

45. The plant part of claim 44, wherein said seed is technically treated, whereby the technical treatment is selected from the group consisting of polishing, pelleting, incrustation, and coloring.

46. The plant part of claim 45 , wherein the technical treatment does not include insecticide .

47. A plant part of claim 1, wherein the plant part is a commodity plant product.

48. The commodity plant product of claim 47, wherein the plant product is a beet.

49. A marker for selection of Beet Mild Yellowing Virus resistant plants selected from the group consisting of SEQ ID NO: 1 to SEQ ID NO: 45.

50. A marker for selection of Beet Mild Yellowing Virus resistant plants selected from the group consisting of SEQ ID NO: 52 to SEQ ID NO: 87.

51. The marker of claim 49, wherein the marker utilizes a sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NO: 11, SEQ ID NO: 14, SEQ ID NO: 17, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 29, SEQ ID NO: 32, SEQ ID NO: 35, SEQ ID NO: 38, SEQ ID NO: 41, and SEQ ID NO: 44.

52. The marker of claim 50, wherein the marker utilizes a sequence selected from the group consisting of SEQ ID NO: 52, SEQ ID NO: 56, SEQ ID NO: 58, SEQ ID NO: 62, SEQ ID NO: 65, SEQ ID NO: 67, SEQ ID NO: 70, SEQ ID NO: 73, SEQ ID NO: 76, SEQ ID NO: 79, SEQ ID NO: 83, and SEQ ID NO: 85.

53. A method of using any one of the molecular markers in claim 49 for selection of a plant resistant against a virus selected from the group consisting of Beet Mild Yellowing Virus (BMYV), Beet yellows virus (BYV), and Beet chlorosis virus (BChV).

54. A method of using any one of the molecular markers in claim 50 for selection of a plant resistant against a virus selected from the group consisting of Beet Mild Yellowing Virus (BMYV), Beet yellows virus (BYV), and Beet chlorosis virus (BChV).

55. The method of claim 53, wherein said molecular markers identify at least one of the Single Nucleotide Polymorphisms present in PBV504245, PBV125552, PBV291217, PBV369685, PBV261963, PBV577030, PBV562771, PBV573138, PBV273480, PBV821051, PBV148969, PBV331644, PBV882826, PBV374371, and PBV757436.

56. The method of claim 54, wherein said molecular markers identify at least one of the Single Nucleotide Polymorphisms present in PBV757437, PBV638722, EPBV6296, PBV738292, PBV738293, EPBV7349, GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821.

57. A method of identifying a plant, plant part, or plant cell comprising a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 1 (QTL1), said method comprising the steps of: screening for the presence of QTL1, wherein QTL1 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV504245, PBV125552, PBV291217, PBV369685, and PBV261963, wherein:PBV504245 is a C to G substitution corresponding to position 1050427 of chromosome 1 of the Refbeet 1.5 reference genome,PBV125552 is a G to A substitution corresponding to position 3069972 of chromosome 1 of the Refbeet 1.5 reference genome,PBV291217 is a G to A substitution corresponding to position 4315236 of chromosome 1 of the Refbeet 1.5 reference genome,PBV369685 is an A to G substitution corresponding to position 4330737 of chromosome 1 of the Refbeet 1.5 reference genome, andPBV261963 is an A to T substitution corresponding to position 4356001 of chromosome 1 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL1.

58. The method of claim 57, wherein said screening for the presence of QTL1 further comprises identifying a plant, plant part, or plant cell having at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV757437, PBV638722, and EPBV6296, wherein:PBV757437 is a G to A substitution corresponding to position 17043 of chromosome 1 of the Refbeet 1.5 reference genome,PBV638722 is an A to G substitution corresponding to position 2645728 of chromosome 1 of the Refbeet 1.5 reference genome, andEPBV6296 is a T to C substitution corresponding to position 1117040 of chromosome 1 of the Refbeet 1.5 reference genome.

59. A method of identifying a plant, plant part, or plant cell comprising a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 4 (QTL2), said method comprising the steps of: screening for the presence of QTL2, wherein QTL2 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV577030, PBV562771, PBV573138, PBV273480, and PBV821051, wherein:PBV577030 is an A to G substitution corresponding to position 5742753 of chromosome 4 of the Refbeet 1.5 reference genome,PBV562771 is a G to A substitution corresponding to position 9767085 of chromosome 4 of the Refbeet 1.5 reference genome,PBV573138 is an A to G substitution corresponding to position 10271308 of chromosome 4 of the Refbeet 1.5 reference genome,PBV273480 is a G to A substitution corresponding to position 46718199 of chromosome 4 of the Refbeet 1.5 reference genome, andPBV821051 is a G to A substitution corresponding to position 47855576 of chromosome 4 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL2.

60. A method of identifying a plant, plant part, or plant cell comprising a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 8 (QTL3), said method comprising the steps of: screening for the presence of QTL3, wherein QTL3 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV148969, PBV331644, PBV882826, PBV374371, and PBV757436, wherein:PBV148969 is an A to G substitution corresponding to position 436005 of chromosome 8 of the Refbeet 1.5 reference genome,PBV331644 is a G to A substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome,PBV882826 is an A to G substitution corresponding to position 7979633 of chromosome 8 of the Refbeet 1.5 reference genome,PBV374371 is a G to A substitution corresponding to position 8822544 of chromosome 8 of the Refbeet 1.5 reference genome, andPBV757436 is an A to C substitution corresponding to position 25201555 of chromosome 8 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL3.

61. The method of claim 60, wherein said screening for the presence of QTL3 further comprises identifying a plant, plant part, or plant cell having at least one single nucleotide polymorphism (SNP) selected from the group consisting of PBV738292, PBV738293, and EPBV7349, wherein:PBV738292 is a G to an A substitution corresponding to position 35831 of chromosome 8 of the Refbeet 1.5 reference genome,PBV738293 is an A to G substitution corresponding to position 1366650 of chromosome 8 of the Refbeet 1.5 reference genome, andEPBV7349 is an A to C substitution corresponding to position 275340 of chromosome 8 of the Refbeet 1.5 reference genome.

62. A method of identifying a plant, plant part, or plant cell comprising a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV) on chromosome 2 (QTL4), said method comprising the steps of: screening for the presence of QTL4, wherein QTL4 is genetically linked to at least one single nucleotide polymorphism (SNP) selected from the group consisting of GRKPBV98281, GRKPBV627372, GRKPBV672273, GRKPBV627178, GRKPBV116271, and EPBV8821, wherein:GRKPBV98281 is a G to A substitution corresponding to position 8040503 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV627372 is a C to an A substitution corresponding to position 9433027 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV672273 is a G to an A substitution corresponding to position 12212298 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV627178 is an Ato C substitution corresponding to position 18410288 of chromosome 2 of the Refbeet 1.5 reference genome,GRKPBV 116271 is an Ato C substitution corresponding to position 20007280 of chromosome 2 of the Refbeet 1.5 reference genome, and identifying a plant, plant part, or plant cell having at least one of said marker loci linked to QTL4.

63. The method of claim 57, wherein the screening for the presence of QTL1 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 2 and SEQ ID NO: 3,PCR amplification of DNA with SEQ ID NO: 5 and SEQ ID NO: 6,PCR amplification of DNA with SEQ ID NO: 8 and SEQ ID NO: 9,PCR amplification of DNA with SEQ ID NO: 11 and SEQ ID NO: 12, andPCR amplification of DNA with SEQ ID NO: 14 and SEQ ID NO: 15.

64. The method of claim 58, wherein the screening for the presence of QTL1 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 52 and SEQ ID NO: 54, PCR amplification of DNA with SEQ ID NO: 56 and SEQ ID NO: 57, and PCR amplification of DNA with SEQ ID NO: 58 and SEQ ID NO: 60.

65. The method of claim 59, wherein the screening for the presence of QTL2 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 17 and SEQ ID NO: 18, PCR amplification of DNA with SEQ ID NO: 20 and SEQ ID NO: 21, PCR amplification of DNA with SEQ ID NO: 23 and SEQ ID NO: 24, PCR amplification of DNA with SEQ ID NO: 26 and SEQ ID NO: 27, and PCR amplification of DNA with SEQ ID NO: 29 and SEQ ID NO: 30.

66. The method of claim 60, wherein the screening for the presence of QTL3 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 32 and SEQ ID NO: 33, PCR amplification of DNA with SEQ ID NO: 35 and SEQ ID NO: 36, PCR amplification of DNA with SEQ ID NO: 38 and SEQ ID NO: 39, PCR amplification of DNA with SEQ ID NO: 41 and SEQ ID NO: 42, and PCR amplification of DNA with SEQ ID NO: 44 and SEQ ID NO: 45.

67. The method of claim 61, wherein the screening for the presence of QTL3 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 62 and SEQ ID NO: 63PCR amplification of DNA with SEQ ID NO: 65 and SEQ ID NO: 66, and PCR amplification of DNA with SEQ ID NO: 67 and SEQ ID NO: 69.

68. The method of claim 62, wherein the screening for the presence of QTL4 comprises at least one of:PCR amplification of DNA with SEQ ID NO: 70 and SEQ ID NO: 72, PCR amplification of DNA with SEQ ID NO: 73 and SEQ ID NO: 75, PCR amplification of DNA with SEQ ID NO: 76 and SEQ ID NO: 78, PCR amplification of DNA with SEQ ID NO: 79 and SEQ ID NO: 81, PCR amplification of DNA with SEQ ID NO: 83 and SEQ ID NO: 84, and PCR amplification of DNA with SEQ ID NO: 85 and SEQ ID NO: 87.

69. A method of producing a Beta vulgaris subsp. vulgaris plant, plant part, or plant cell having resistance to Beet Mild Yellowing Virus (BMYV), said method comprising the steps of:(a) providing a plant having resistance to Beet Mild Yellowing Virus (BMYV);(b) crossing the plant of (a) with another plant and harvesting the seed resulting from said cross;(c) growing the seed from step (b) to produce a progeny plant, and submitting the progeny plant to the method of identifying a plant comprising at least one of a Quantitative Trait Locus (QTL) associated with resistance to Beet Mild Yellow Virus (BMYV); and(d) selecting a progeny plant which comprises at least one of QTL1, QTL2, and QTL3.

70. The method of claim 69, wherein selecting further comprises selecting a progeny plant having QTL4.

71. The method of claim 69, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 2 and SEQ ID NO: 3,PCR amplification of DNA with SEQ ID NO: 5 and SEQ ID NO: 6,PCR amplification of DNA with SEQ ID NO: 8 and SEQ ID NO: 9,PCR amplification of DNA with SEQ ID NO: 11 and SEQ ID NO: 12, andPCR amplification of DNA with SEQ ID NO: 14 and SEQ ID NO: 15.

72. The method of claim 69, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 52 and SEQ ID NO: 54,PCR amplification of DNA with SEQ ID NO: 56 and SEQ ID NO: 57, andPCR amplification of DNA with SEQ ID NO: 58 and SEQ ID NO: 60.

73. The method of claim 69, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 17 and SEQ ID NO: 18,PCR amplification of DNA with SEQ ID NO: 20 and SEQ ID NO: 21,PCR amplification of DNA with SEQ ID NO: 23 and SEQ ID NO: 24,PCR amplification of DNA with SEQ ID NO: 26 and SEQ ID NO: 27, andPCR amplification of DNA with SEQ ID NO: 29 and SEQ ID NO: 30.

74. The method of claim 69, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 32 and SEQ ID NO: 33,PCR amplification of DNA with SEQ ID NO: 35 and SEQ ID NO: 36,PCR amplification of DNA with SEQ ID NO: 38 and SEQ ID NO: 39,PCR amplification of DNA with SEQ ID NO: 41 and SEQ ID NO: 42, andPCR amplification of DNA with SEQ ID NO: 44 and SEQ ID NO: 45.

75. The method of claim 69, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 62 and SEQ ID NO: 63PCR amplification of DNA with SEQ ID NO: 65 and SEQ ID NO: 66, andPCR amplification of DNA with SEQ ID NO: 67 and SEQ ID NO: 69.

76. The method of claim 69, wherein said selecting a progeny comprises at least one of:PCR amplification of DNA with SEQ ID NO: 70 and SEQ ID NO: 72,PCR amplification of DNA with SEQ ID NO: 73 and SEQ ID NO: 75,PCR amplification of DNA with SEQ ID NO: 76 and SEQ ID NO: 78,PCR amplification of DNA with SEQ ID NO: 79 and SEQ ID NO: 81,PCR amplification of DNA with SEQ ID NO: 83 and SEQ ID NO: 84, andPCR amplification of DNA with SEQ ID NO: 85 and SEQ ID NO: 87.

77. The method of claim 69, further comprising(e) backcrossing said selected progeny plant to a parental line to produce a backcross progeny having two or more QTLs associated with resistance to Beet Mild Yellowing Virus.

78. The method of claim 69, further comprising(e) backcrossing said selected progeny plant to a parental line to produce backcross progeny having a desirable trait and resistance to Beet Mild Yellowing Virus.

79. The method of claim 69, further comprising introducing or introgressing a desirable trait introduced by a method selected from the group consisting of genetic transformation, genome editing, targeted mutagenesis, and induced random mutagenesis.

80. The method of claim 78, wherein said desirable trait is selected from the group consisting of (i) the H7-1 event conferring glyphosate tolerance, (ii) a mutated Acetolactate Synthase (ALS) gene conferring tolerance against ALS herbicides, (iii) the GTSB77 event conferring glyphosate tolerance, and (iv) the T 120-7 event conferring glufosinate tolerance.

81. The method of claim 80, wherein the ALS gene encodes an ALS polypeptide containing an amino acid different from tryptophan at a position 569 of the ALS polypeptide.

82. The method of claim 69, further comprising introgressing a Beet Mild Yellowing Virus tolerance trait obtainable from the group of sugar beet varieties comprising Maruscha KWS and Novalina KWS.

83. The method of claim 69, wherein the selected progeny plant or backcross progeny plant is selfed or asexually propagated.

84. A method for reducing yield loss as a consequence of Beet Mild Yellowing Virus (BMYV) infection, the method comprising the steps of:(a) providing a seed for a plant having resistance to Beet Mild Yellowing Virus (BMYV), a plant identified by the method of any one of claims 57-68, or a plant produced by the method of any one of claims 69-83; and(b) planting said seed in areas which are prone to Beet Mild Yellowing Virus infection.

85. The method of claim 84, wherein the seed is planted in areas where the use of insecticides to control the vector for Beet Mild Yellowing Virus transmission is restricted, prohibited, or not desired.

86. A method for producing sugar, the method comprising the steps of:(a) growing the plant having resistance to Beet Mild Yellowing Virus (BMYV), a plant identified by the method of any one of claims 57-68, or a plant produced by the method of any one of claims 69-83;(b) harvesting the root / beet of said plant, and(c) extracting the sugar from said root / beet of (b).

87. The method of claim 86, wherein the growing is conducted without the use of insecticides and the sugar extracted from said root / beet is qualified for the organic market.

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