Cultivation method of disease-resistant rice

Abstract

The invention belongs to the technical field of rice cultivation, and provides a disease-resistant rice cultivation method which comprises the following steps: selecting a donor parent with a disease-resistant gene and QTL (Quantitative Trait Loci) and an excellent receptor parent, and hybridizing to obtain a filial generation; carrying out genotype identification on the filial generation by using a molecular marker closely linked with the disease-resistant gene and the QTL, and screening out an individual with a target gene and the QTL as a backcross parent; backcrossing the screened backcross parent and the receptor parent to obtain a backcross progeny; repeating the steps S2 and S3 until the genotype of the backcross parent is close to that of the receptor parent, and meanwhile, retaining the target gene and the QTL; performing phenotype identification on the backcross progeny, and selecting excellent individuals as cultivated varieties; the disease resistance, yield and breeding efficiency of disease-resistant rice can be effectively improved, occurrence and harm of diseases are reduced, the use and cost of pesticides are reduced, the genetic diversity of rice is enriched, and the adaptability of rice is improved.

Description

Technical Field

[0001] This invention belongs to the field of rice cultivation technology, specifically a method for cultivating disease-resistant rice. Background Technology

[0002] Rice diseases and pests are major natural disasters that seriously affect the stable and high yield of rice and the optimization of its quality, restricting the realization of rice's potential for increased production and seriously threatening the safe planting of rice. The annual rice planting area in Guangxi Zhuang Autonomous Region is about 34 million mu, with an overall disease and pest occurrence level of 4 (5) and an annual occurrence area of ​​about 90 million mu. Rice stem borers (three-stemmed stem borer, two-stemmed stem borer), rice planthoppers, rice leaf rollers, rice gall midges, rice blast, rice stripe disease, white leaf blight, etc. are the most important rice diseases and pests in Guangxi. In recent years, they have generally occurred at a moderate to severe level. Rice planthoppers, three-stemmed stem borers, rice leaf rollers, and rice blast have reached a large-scale occurrence level in some areas, with an occurrence area of ​​about 55 million mu. It can be seen that rice diseases pose the greatest threat to grain production in our region and cause great economic losses to farmers. In terms of production, there is a lack of a rice variety that can prevent diseases and pests without relying on chemical pesticides. Moreover, the use of pesticides leaves residues and seriously pollutes the environment.

[0003] Rice varieties that are resistant to diseases and pests are popular among farmers because they are easy to use, economical, and environmentally friendly. With the continuous research and development by scholars from various countries, a series of varieties that are highly resistant to rice leaf rollers and rice stem borers and other lepidopteran pests have been developed. However, there are very few varieties that are resistant to diseases such as rice blast, rice stripe, and white leaf blight. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for cultivating disease-resistant rice, thereby resolving the issues raised in the background section.

[0005] A method for cultivating disease-resistant rice, comprising the following steps:

[0006] S1. Select donor parents with disease-resistant genes and QTLs and excellent recipient parents, and hybridize them to obtain hybrid offspring;

[0007] S2. Genotyping of hybrid offspring is performed using molecular markers closely linked to disease resistance genes and QTLs, and individuals carrying the target gene and QTL are selected as backcross parents.

[0008] S3. The selected backcross parents are backcrossed with the recipient parents to obtain backcross offspring;

[0009] S4. Repeat steps S2 and S3 until the genotype of the backcross parent is close to that of the recipient parent, while preserving the target gene and QTL.

[0010] S5. Perform phenotypic identification on the backcross offspring and select superior individuals as the breeding varieties.

[0011] Preferably, the disease-resistant gene includes at least one of Xa21, Xa4, Pi9, Pi-z, and PICI1.

[0012] Preferably, the superior recipient parent has excellent agronomic traits such as high yield, early maturity, and strong stress resistance, and is easy to breed and has no recessive pathogenic genes.

[0013] Preferably, step S2 specifically includes:

[0014] S201. Randomly select individuals from the hybrid offspring and extract their DNA samples;

[0015] S202. Select molecular markers closely linked to disease resistance genes and QTLs, including SSRs and SNPs, and perform PCR amplification.

[0016] S203. The genotype of each individual is determined by detecting the polymorphism of molecular markers through electrophoresis and sequencing;

[0017] S204. Based on the genotype data, individuals carrying the target gene and QTL are selected as backcross parents.

[0018] Preferably, step S4 involves calculating the genotype similarity between the new backcross parent and the recipient parent, including the backcross recovery rate Rc and the backcross selection coefficient Rsc, until Rc > 0.9 or Rsc > 0.95, at which point the backcrossing is stopped; if the similarity does not meet the standard, steps S1 to S4 are repeated until the standard is met.

[0019] The formula for the backcross recovery rate Rc is expressed as:

[0020]

[0021] Where n represents the number of molecular markers, a i A represents the number of alleles of the i-th molecular marker that are identical to those of the recipient parent in the backcross parent. i Rc represents the total number of alleles of the i-th molecular marker. The value of Rc is between 0 and 1. The closer it is to 1, the closer the genotype of the backcross parent is to the genotype of the recipient parent.

[0022] The formula for the backcross selection coefficient Rsc is as follows:

[0023]

[0024] Where n represents the number of molecular markers, a i A represents the number of alleles of the i-th molecular marker that are identical to those of the recipient parent in the backcross parent.i This represents the total number of alleles for the i-th molecular marker. Indicates a i The average value, A represents i The average value of Rsc is between -1 and 1. The closer it is to 1, the closer the genotype of the backcross parent is to the genotype of the recipient parent. The closer it is to -1, the closer the genotype of the backcross parent is to the genotype of the donor parent.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention improves the disease resistance, yield, and breeding efficiency of disease-resistant rice by screening individuals carrying target genes and QTLs as backcross parents, preserving the target genes and QTLs, thereby reducing the occurrence and damage of diseases, lowering pesticide use and costs, enriching the genetic diversity of rice, and increasing the adaptability of rice. Attached Figure Description

[0027] Fig. 1 This is a flowchart of the overall cultivation method steps of the present invention;

[0028] Fig. 2 This is a detailed flowchart of the second step of the overall cultivation method of the present invention. Detailed Implementation

[0029] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0030] As attached Figs. 1-2 As shown:

[0031] Example 1: This invention provides a method for cultivating disease-resistant rice, comprising the following steps:

[0032] S1. Select donor parents with disease-resistant genes and QTLs and excellent recipient parents, and hybridize them to obtain hybrid offspring;

[0033] S2. Genotyping of hybrid offspring is performed using molecular markers closely linked to disease resistance genes and QTLs, and individuals carrying the target gene and QTL are selected as backcross parents.

[0034] S3. The selected backcross parents are backcrossed with the recipient parents to obtain backcross offspring;

[0035] S4. Repeat steps S2 and S3 until the genotype of the backcross parent is close to that of the recipient parent, while preserving the target gene and QTL.

[0036] S5. Perform phenotypic identification on the backcross offspring and select superior individuals as the breeding varieties.

[0037] Disease resistance genes include at least one of Xa21, Xa4, Pi9, Pi-z, and PICI1.

[0038] Excellent recipient parents possess superior agronomic traits such as high yield, early maturity, and strong stress resistance, and are easy to breed, without recessive pathogenic genes.

[0039] The specific steps for S2 are as follows:

[0040] S201. Randomly select individuals from the hybrid offspring and extract their DNA samples;

[0041] S202. Select molecular markers closely linked to disease resistance genes and QTLs, including SSRs and SNPs, and perform PCR amplification.

[0042] S203. The genotype of each individual is determined by detecting the polymorphism of molecular markers through electrophoresis and sequencing;

[0043] S204. Based on the genotype data, individuals carrying the target gene and QTL are selected as backcross parents.

[0044] S4 calculates the genotype similarity between the new backcross parent and the recipient parent, including the backcross recovery rate Rc and the backcross selection coefficient Rsc, until Rc > 0.9 or Rsc > 0.95, at which point the backcrossing stops; if the similarity does not meet the standard, S1 to S4 are repeated until the standard is met.

[0045] The formula for the backcross recovery rate Rc is expressed as:

[0046]

[0047] Where n represents the number of molecular markers, a i A represents the number of alleles of the i-th molecular marker that are identical to those of the recipient parent in the backcross parent. i Rc represents the total number of alleles of the i-th molecular marker. The value of Rc is between 0 and 1. The closer it is to 1, the closer the genotype of the backcross parent is to the genotype of the recipient parent.

[0048] The formula for the backcross selection coefficient Rsc is expressed as:

[0049]

[0050] Where n represents the number of molecular markers, a i A represents the number of alleles of the i-th molecular marker that are identical to those of the recipient parent in the backcross parent. i This represents the total number of alleles for the i-th molecular marker. Indicates a i The average value, A represents i The average value of Rsc is between -1 and 1. The closer it is to 1, the closer the genotype of the backcross parent is to the genotype of the recipient parent. The closer it is to -1, the closer the genotype of the backcross parent is to the genotype of the donor parent.

[0051] Experimental Example: Using the indica rice line 75-1-127 as the donor parent of the broad-spectrum and durable rice blast resistance gene Pi9, and successively using the indica three-line maintainer line Sanxiang B and its sterile line Sanxiang A as recipient parents, molecular marker-assisted selection and continuous backcross breeding were carried out using the co-dominant InDel marker CoInDF1R1 in the Pi9 gene to directionally improve the rice blast resistance of Sanxiang B and Sanxiang A. Using Sanxiang B, Sanxiang A, 75-1-127 and the susceptible control CO39 as materials, an indoor seedling blast inoculation experiment was conducted with 28 rice blast fungus strains from different rice-growing areas at home and abroad. The results showed that the resistance frequency of 75-1-127 was 85.71%, while the resistance frequencies of Sanxiang A and Sanxiang B were both 28.57%. The codominant marker CoInDF1R1 amplified a clear 320 bp band from the 75-1-127 genome, while the amplification product from the Sanxiang A and Sanxiang B genomes was approximately 410 bp, showing significant and stable polymorphism.

[0052] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), installation arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0053] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the best mode of carrying out the invention as currently considered, or those features that are not relevant to implementing the invention) may be omitted.

[0054] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0055] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for breeding disease-resistant rice, characterized by, The method comprises the following steps: S1, selecting a donor parent with a disease-resistant gene and a QTL and an excellent recipient parent, and performing hybridization to obtain hybrid offspring; S2, performing genotype identification on the hybrid offspring by using a molecular marker closely linked to the disease-resistant gene and the QTL, and screening an individual with the target gene and the QTL as a backcross parent; S3, performing backcrossing on the screened backcross parent and the recipient parent to obtain backcross offspring; S4, repeating steps S2 and S3 until the genotype of the backcross parent is close to that of the recipient parent, while the target gene and the QTL are retained; S5, performing phenotype identification on the backcross offspring, and selecting an excellent individual as a cultivated later-generation variety.

2. The method for breeding disease resistant rice plants of claim 1, wherein: The disease-resistant gene comprises at least one of Xa21, Xa4, Pi9, Pi-z, and PICI1.

3. The method of claim 1, wherein the rice plant is resistant to the disease.

3. The method of claim 1, wherein the rice plant is resistant to the disease. The excellent recipient parent has excellent agronomic characteristics such as high yield, early maturity, and strong stress resistance, is easy to breed, and has no hidden pathogenic genes.

4. The method for breeding disease resistant rice plants of claim 1, wherein: The specific steps of S2 are as follows: S201, randomly extracting an individual from the hybrid offspring, and extracting a DNA sample of the individual; S202, selecting a molecular marker closely linked to the disease-resistant gene and the QTL, including SSR and SNP, and performing PCR amplification; S203, detecting polymorphism of the molecular marker by electrophoresis and sequencing, and determining the genotype of each individual; S204, screening an individual with the target gene and the QTL as the backcross parent according to the genotype data result.

5. The method for breeding disease resistant rice plants of claim 1, wherein: S4 is performed by calculating the genotype similarity between the new backcross parent and the recipient parent, including a backcross recovery rate Rc and a backcross selection coefficient Rsc, until Rc>0.9 or Rsc>0.95, and then the backcrossing is stopped; if the similarity does not meet the standard, steps S1 to S4 are repeatedly performed until the standard is met; The formula of the backcross recovery rate Rc is as follows: wherein n represents the number of molecular markers, a i represents the number of alleles of the i-th molecular marker that are identical to those of the recipient parent in the backcross parent, A i represents the total number of alleles of the i-th molecular marker, the value of Rc being comprised between 0 and 1, the closer to 1 indicating that the genotype of the backcross parent is closer to that of the recipient parent; The formula of the backcross selection coefficient Rsc is as follows: wherein n represents the number of molecular markers, a i represents the number of alleles of the i-th molecular marker that are identical to those of the recipient parent in the backcross parent, A i represents the total number of alleles of the i-th molecular marker, represents the average value of a i , and represents the average value of A i , and the value of Rsc is between -1 and 1, the closer to 1 indicating that the genotype of the backcross parent is closer to that of the recipient parent, and the closer to -1 indicating that the genotype of the backcross parent is closer to that of the donor parent.

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