Ibmyb4 protein and use thereof

Abstract

The application relates to the biotechnology field and discloses a protein IbMYB4 related to sweet potato stem nematode disease resistance and application thereof. The application discloses application of IbMYB4 protein in improving sweet potato stem nematode disease resistance. Experiments prove that overexpression of the IbMYB4 gene in sweet potato can enhance the resistance of the sweet potato to stem nematodes.

Description

Technical Field

[0001] This invention relates to the biotechnology field of the protein IbMYB4, which is associated with resistance to sweet potato stem nematode disease, and its applications. Background Technology

[0002] The MYB family is one of the largest gene families in plants. MYB family genes are widely involved in regulating plant secondary metabolism, morphogenesis, responses to environmental factors and hormones, and disease resistance. In plants, MYB transcription factors possess a highly conserved MYB domain at their N-terminus. This domain typically includes 1-4 tandemly linked incomplete repeat units of 51-52 amino acids each. Each repeat unit contains 51-52 amino acids that can form three α-helices, with the latter two forming a helix-turn-helix (HTH) structure that binds to the major groove of DNA. The three spacer tryptophan residues within each repeat unit have hydrophobic properties, contributing to the stability of the HLH helical structure. In plants, MYB transcription factors play a crucial role in responding to abiotic stresses. Overexpression of the Arabidopsis thaliana AtMYB2 and AtMYB60 genes enhances drought tolerance (Hoeren et al., 1998; Cominelli et al., 2005). AtMYB68 has been shown to participate in high-temperature responses (Feng et al., 2004). Overexpression of the OsMYB4 gene significantly improves the tolerance of rice plants to stresses such as high salinity and drought (Vannini et al., 2004). In addition, MYB transcription factors also play important roles in plant responses to various environmental factors such as hypoxia, hormone induction, and UV-B radiation.

[0003] Sweet potato stem nematode disease is caused by the potato rot nematode (Ditylenchus destructor). The stem nematode is highly tolerant of low temperatures, reproduces year-round, and can continuously damage sweet potatoes throughout their growth and storage periods. Based on symptoms, stem nematode disease can be classified into "hollow heart type," "hollow skin type," and "mixed type." Infection typically causes a 30%-50% yield reduction, and in severe cases, can lead to total crop failure. In recent years, the disease has spread rapidly and become increasingly severe, posing a serious threat to sweet potato production and becoming one of the three major sweet potato diseases. Therefore, improving resistance to sweet potato stem nematode disease is of great significance. Cloning stem nematode resistance-related genes in sweet potatoes and studying their functions is therefore of great importance. Discovering new genes with stress resistance and utilizing them through bioengineering is an effective way to improve plant stress resistance.

[0004] Currently, there are no reports on the role of MYB4 in stem nematode resistance. Therefore, cloning stem nematode resistance-related genes in sweet potato and studying their functions is of great significance. Discovering new genes with stress resistance and utilizing them through bioengineering is an effective way to improve plant stress resistance. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to improve resistance to sweet potato stem nematode disease.

[0006] To solve the above-mentioned technical problems, the present invention first provides the application of IbMYB4 protein, substances that increase the expression level of the IbMYB4 protein encoding gene, and substances that increase the content or activity of IbMYB4 protein in improving sweet potato stem nematode resistance;

[0007] The IbMYB4 protein is a protein of type A1, A2, or A3 as follows:

[0008] A1. The amino acid sequence is the protein that is the amino acid sequence shown in SEQ ID No. 2 of the sequence listing;

[0009] A2, a protein obtained by substituting and / or deleting and / or adding amino acid residues of the amino acid sequence shown in SEQ ID No. 2 in the sequence listing, which has more than 80% identity with the protein shown in A1) and is associated with resistance to sweet potato stem nematode disease;

[0010] A3, a fusion protein obtained by attaching a protein tag to the N-terminus and / or C-terminus of A1 or A2).

[0011] In the above application, SEQ ID No.2 in the sequence listing consists of 239 amino acid residues.

[0012] In the above applications, identity refers to the identity of amino acid sequences. The identity of amino acid sequences can be determined using homology search sites on the Internet, such as the BLAST page on the NCBI homepage. For example, in Advanced BLAST 2.1, using blastp as the procedure, setting the Expect value to 10, setting all filters to OFF, using BLOSUM62 as the matrix, setting the Gap existence cost, Per residue gap cost, and Lambda ratio to 11, 1, and 0.85 (default values) respectively, and performing an identity search on a pair of amino acid sequences, the identity value (%) can then be obtained.

[0013] In the above applications, the 80% or more of identity can be at least 81%, 85%, 90%, 91%, 92%, 95%, 96%, 98%, 99%, or 100% identity.

[0014] In the above applications, the IbMYB4 protein can be derived from sweet potatoes.

[0015] In the above applications, substances that increase the expression level of the IbMYB4 protein-encoding gene, or substances that increase the content or activity of the IbMYB4 protein, can be substances that perform at least one of the following six types of regulation: B1) regulation at the transcriptional level of the gene; B2) post-transcriptional regulation of the gene (i.e., regulation of the splicing or processing of the primary transcript of the gene); B3) regulation of RNA transport of the gene (i.e., regulation of the transport of mRNA of the gene from the nucleus to the cytoplasm); B4) regulation of the translation of the gene; B5) regulation of mRNA degradation of the gene; and B6) post-translational regulation of the gene (i.e., regulation of the activity of the protein translated from the gene).

[0016] In the above applications, the substance that increases the expression level of the IbMYB4 protein-encoding gene, or the substance that increases the content or activity of the IbMYB4 protein, is a biological material related to the IbMYB4 protein; the biological material is any one of the following C1-C3:

[0017] C1. The nucleic acid molecule encoding the IbMYB4 protein;

[0018] C2. Nucleic acid molecules that enhance the expression of the IbMYB4 protein;

[0019] C3, expression cassettes, recombinant vectors, recombinant microorganisms, transgenic plant cell lines, transgenic plant tissues, or transgenic plant organs containing nucleic acid molecules described in C1 or C2.

[0020] In the above applications, the nucleic acid molecule described in C1 or C2 can be DNA, such as cDNA, genomic DNA, or recombinant DNA; the nucleic acid molecule can also be RNA, such as mRNA or hnRNA.

[0021] In the above applications, the nucleic acid molecule described in C1 may specifically be a nucleic acid molecule whose coding sequence is SEQ ID No. 1 in the sequence listing.

[0022] In this application, the improvement of sweet potato stem nematode resistance can be manifested in any of the following ways:

[0023] Z1. The weight loss rate of potato tubers decreased when infected by stem nematodes;

[0024] Z2. The area infected by stem nematodes in potato tubers decreased during stem nematode infestation.

[0025] Z3. Lignin content increases when stem nematodes infect the plant.

[0026] The present invention also provides a method for improving the resistance of sweet potato to stem nematodes, the method comprising step M, wherein step M is to enhance, increase or upregulate the activity and / or content of the IbMYB4 protein in the target sweet potato, or / and enhance, increase or upregulate the expression level of the gene encoding the IbMYB4 protein, so as to improve the resistance of sweet potato to stem nematodes.

[0027] This invention provides an IbMYB4 protein and its encoding gene. When this gene was introduced into the sweet potato cultivar *Chestnut Fragrance*, IbMYB4-transgenic sweet potato plants were obtained. Compared to the wild type, these plants exhibited enhanced resistance to stem nematodes. This invention has broad application prospects and a promising market outlook in the agricultural field. Attached Figure Description

[0028] Figure 1 The results are PCR amplification results of transgenic sweet potato plants; where M is the DNA molecular marker DL2000, WT is the wild-type sweet potato plant, P is the plasmid control (pCB-IbMYB4), and L1, L2, L3 and L4 are all sweet potato plants transgenic with the IbMYB4 gene.

[0029] Figure 2 The relative expression levels of the IbMYB4 gene in IbMYB4-transgenic sweet potato plants and wild-type plants are shown in the figure. The internal control gene is the sweet potato actin gene. Among them, WT is wild-type sweet potato, and L1, L2, L3, and L4 are IbMYB4-transgenic sweet potato lines. The data shown in the figure are mean ± standard deviation, with 3 replicates. ** indicates that the significance analysis result compared with the control WT is P < 0.01.

[0030] Figure 3 To identify the stem nematode resistance of IbMYB4 transgenic sweet potato plants L1 and L2 and wild-type sweet potato plant WT; where A is the phenotypic identification result; B is the statistical result of weight loss rate; C is the statistical result of diseased area after nematode infection; D is the result of lignin content determination; WT is wild-type sweet potato, and the control is not inoculated with stem nematodes. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0032] In the quantitative experiments described below, three replicate experiments were conducted, and the average value of the results was taken.

[0033] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0034] The sweet potato variety JS6-5 used in the following examples is described in the following literature: Zhao HY, Zhang SS, Wang FB, Zhao N, He SZ, Liu QC, Zhai H* (2018): Comparative transcriptome analysis of purple-fleshed sweet potato provides insights into the molecular mechanism of anthocyanin biosynthesis. Frontiers of Agricultural Science and Engineering, 2018, 5(2): 214-225, doi:org / 10.15302 / J-FASE-2018219. With the authors' consent, the public can obtain this variety from the Sweet Potato Genetics and Breeding Laboratory of China Agricultural University to replicate this experiment.

[0035] The sweet potato variety Chestnut Fragrance used in the following examples is described in the following literature: Zhang et al (2017) (Zhang Q, Wang YN, Li Y, Zhai H, Liu QC, He SZ. Characterization of salt tolerance and fusarium wilt resistance of a sweet potato mutant. 2017, Journal of Integrative Agriculture. 16(0):60345-7). It is available to the public from the Sweet Potato Genetics and Breeding Laboratory of China Agricultural University to replicate this experiment.

[0036] The plant total RNA extraction kit used in the following examples is the Transzol Up Plant Total RNA Extraction Kit from TransGen Biotech (Beijing), product catalog number ET111.

[0037] The QuantScript RT Kit used in the following examples is a product of TIANGEN (Beijing) Co., Ltd., with product catalog number KR103.

[0038] The vector pCAMBIA3301 used in the following examples is a product of UBO Biotechnology Co., Ltd., with product number VT1386.

[0039] The vector pBI121 used in the following examples is a product of UBO Biotechnology Co., Ltd., with product number VT1388.

[0040] The pEASY-Blunt simple vector used in the following examples is a product of Beijing TransGen Biotech Co., Ltd., with product catalog number CB111-01.

[0041] The following examples use SPSS statistical software to process the data. The experimental results are expressed as mean ± standard deviation. The Student t-test is used. P < 0.05 (*) indicates a significant difference, and P < 0.01 (**) indicates a highly significant difference.

[0042] Example 1: Obtaining the IbMYB4 gene

[0043] The steps for obtaining the IbMYB4 gene are as follows:

[0044] 1. Total RNA was extracted from the young leaves of sweet potato variety JS6-5 using a plant total RNA extraction kit. The total RNA was then reverse transcribed into first-strand cDNA using the QuantScript RT Kit Quant cDNA First-Strand Synthesis Kit.

[0045] 2. Design and synthesize primers OF and OR. Use the cDNA obtained in step 1 as a template to perform PCR amplification, obtain a PCR amplification product of about 720 bp and sequence it.

[0046] Primer sequences:

[0047] OF: 5′-ATGGTGAGGGCTCCTTGCT-3′;

[0048] OR: 5′-TCACGATGTATTTCCAGCATTAATA-3′.

[0049] Sequencing results showed that the nucleotide sequence of the PCR amplification product is shown in SEQ ID NO.1 from position 1 to 720 from the 5′ end. The gene represented by this sequence is named the IbMYB4 gene, and the protein encoded by this gene is named IbMYB4. The amino acid sequence of this protein is shown in SEQ ID NO.2.

[0050] Example 2: Application of IbMYB4 protein in improving resistance to sweet potato stem nematode disease

[0051] I. Construction of Recombinant Plasmids

[0052] 1. The vector pCAMBIA3301 was digested with the restriction endonucleases HindIII and EcoRI, and the 11256 bp vector backbone was recovered.

[0053] 2. The vector pBI121 was digested with the restriction endonucleases HindIII and EcoRI, and the fragment containing approximately 3032 bp was recovered.

[0054] 3. Connect fragment 1 to vector backbone 1 to obtain recombinant plasmid pCBGUS.

[0055] 4. The recombinant plasmid pCBGUS was digested with restriction endonucleases BglII and PmlI, and the vector backbone of approximately 12388 bp was recovered.

[0056] 5. The double-stranded DNA molecule shown in SEQ ID NO.1 was artificially synthesized. Using this double-stranded DNA molecule as a template, primer OE-F-BglⅡ:5'-GA was used. AGATCT ATGGTGAGGGCTCCTTGCT-3' (underlined is the recognition sequence of restriction endonuclease BglⅡ) and primer OE-R-PmlI: 5'-GC CACGTG PCR amplification was performed using a primer pair consisting of TCACGATGTATTTCCAGCATTAATA-3' (the underlined part is the recognition sequence of the restriction endonuclease PmlI) to obtain a double-stranded DNA molecule containing the restriction endonuclease recognition sequence.

[0057] 6. The double-stranded DNA molecule containing the restriction endonuclease recognition sequence obtained in step 5 is ligated into the pEASY-Bluntsimple vector to obtain an intermediate vector.

[0058] 7. The intermediate vector was digested with restriction endonucleases BglII and PmlI to recover fragment 2, which is about 700 bp.

[0059] 8. Connect fragment 2 to vector backbone 2 to obtain recombinant plasmid pCB-IbMYB4.

[0060] The recombinant plasmid pCB-IbMYB4 was sequenced. Based on the sequencing results, the structure of the recombinant plasmid pCB-IbMYB4 is described as follows: The small fragment between the restriction endonuclease BglII and PmlI recognition sequences of the recombinant plasmid pCBGUS was replaced with the DNA molecule shown in SEQ ID NO.1, resulting in the recombinant plasmid. The recombinant plasmid pCB-IbMYB4 expresses the IbMYB4 protein shown in SEQ ID NO.2.

[0061] II. Obtaining IbMYB4-transferred sweet potato plants

[0062] 1. The recombinant plasmid pCB-IbMYB4 was transformed into Agrobacterium tumefaciens EHA105 competent cells (purchased from Beijing Bairddi Biotechnology Co., Ltd.) to obtain recombinant Agrobacterium, which was named EHA105 / pCB-IbMYB4.

[0063] 2. Obtaining IbMYB4 sweet potatoes

[0064] (1) Transformation

[0065] The coding sequence of IbMYB4 was introduced into the sweet potato variety Chestnut Fragrance using an Agrobacterium-mediated method, as follows:

[0066] 1) Select embryogenic cell clusters of the sweet potato variety *Chestnut Fragrance*, with a diameter of 0.7-1.3 mm, after approximately 3 days of suspension culture. Suspend these clusters in the prepared *Agrobacterium* EHA105 / pCB-IbMYB4 bacterial suspension (prepared in the previous step). After 5 minutes, aspirate the bacterial suspension. Inoculate the infected embryogenic cell clusters onto solid culture medium (30 mg / L AS, 2.0 mg / L 2,4-D MS). Culture at 28°C in the dark for 3 days.

[0067] The preparation method of embryogenic cell clusters of the sweet potato variety Chestnut Fragrance was based on the method in the literature "Yu B, Zhai H, Wang YP, Zang N, He SZ, Liu QC. Efficient Agrobacterium tumefaciens-mediated transformation using embryogenic suspension cultures in sweet potato, Ipomoea batatas (L.) Lam. 2007, Plant Cell, Tissue & Organ Culture, 90(3):265-273".

[0068] 2) After co-culturing for 3 days, the embryogenic cell masses were washed twice with MS liquid medium containing 500 mg / L Carb and 2.0 mg / L 2,4-D. The embryogenic cell masses were then transferred to solid MS medium containing 2.0 mg / L 2,4-D, 100 mg / L Carb, and 0.3-0.6 mg / L PPT for selection culture at 27±1℃ in the dark, with subculture every 2 weeks. After 10-12 weeks of selection culture, the cells were transferred to solid MS medium containing 1.0 mg / L ABA and 100 mg / L Carb for somatic embryo induction at 27±1℃, 13 h / day light, and 3000 lx illumination. After 2-4 weeks, the resistant callus tissue was transferred to MS basal medium at 27±1℃, 13 h / day light, and 3000 lx illumination. After 4-8 weeks, complete regenerated plants were formed, which were the proposed transgenic plants.

[0069] (2) Genetically modified organism (GMO) detection

[0070] A: PCR testing

[0071] Genomic DNA was extracted from the transgenic plants and wild-type chestnut sweet potato plants using the CTAB method. PCR detection was performed using standard methods, with the amplified fragment length expected to be approximately 800 bp. The primers used were:

[0072] P1: 5'-GACGCACAATCCCACTATCC-3'

[0073] P2: 5'-TCACGATGTATTTCCAGCATTAATAAG-3'.

[0074] In a 0.2 ml Eppendorf centrifuge tube, add 2 μl of 10×PCR buffer, 1 μl of 4 dNTPs (10 mol / L), 1 μl of primers (10 μmol / L), 2 μl of template DNA (50 ng / μl), and 1 μl of Taq DNA polymerase, then add H2O to a total volume of 20 μl. The reaction program is: denaturation at 94℃ for 4 min, annealing at 57℃ for 1.5 min, and extension at 72℃ for 1 min 30 s, for a total of 35 cycles. Wild-type chestnut sweet potato plants were used as a negative control. Electrophoresis was then performed for detection.

[0075] See results Figure 1 As can be seen from the figure, the transgenic plants L1, L2, L3 and L4 all amplified the target band of about 800 bp, indicating that these plants are transgenic plants.

[0076] B: Expression analysis of the IbMYB4 gene

[0077] The transgenic plants L1, L2, L3 and L4 identified in A were propagated: transgenic plant L1 was propagated to obtain transgenic line L1, transgenic plant L2 was propagated to obtain transgenic line L2, transgenic plant L3 was propagated to obtain transgenic line L3, and transgenic plant L4 was propagated to obtain transgenic line L4.

[0078] Using wild-type sweet potato plants as a control, RNA was extracted from whole plants of wild-type and all transgenic lines using the TroZol kit. The expression level of the IbMYB4 gene was detected by qRT-PCR. The SYBR Premix Ex Taq kit was a product of TaKaRa (Takara Bio Inc., Dalian) (catalog number: RR420). Primers P3 and P4 were used for expression level analysis.

[0079] P3:5′-GCGGGAAGAGTTGTAGGCTT-3′;

[0080] P4: 5′-CGAGTGTTTGGTGCAGTTGG-3′.

[0081] Using the sweet potato actin gene as an internal control, the primer sequences are as follows:

[0082] P5: 5′-AGCAGCATGAAGATTAAGGTTGTAGCAC-3′

[0083] P6: 5′-TGGAAAATTAGAAGCACTTCCTGTGAAC-3′

[0084] The experimental results are shown in Figure 2 The results showed that the expression level of the IbMYB4 gene was significantly increased in transgenic lines L1, L2, L3 and L4 compared with the wild-type (WT).

[0085] 3. Identification of stem nematode resistance in transgenic plants

[0086] 3.1 Identification of stem nematode inoculation in transgenic plants

[0087] The stem nematode resistance of IbMYB4 transgenic sweet potato tubers was assessed, following the method described in the literature "Gao S, Yu B, Yuan L, Zhai H, He SZ, Liu QC. Production of transgenic sweet potato plants resistant to stem nematodes using oryzacystatin-I gene. Scientia Horticulturae, 2011, 128:408-414". Wild-type chestnut-scented sweet potato tubers were used as a control.

[0088] The specific method is as follows:

[0089] (1) Propagation culture and isolation of sweet potato stem nematodes

[0090] 1) The nematodes were isolated using the shallow dish method, precipitated in a beaker at room temperature, and then transferred to a 1.5 ml centrifuge tube. The nematodes were centrifuged at 5000 rpm for 2 min at room temperature to collect them. The stylets and tails of the nematodes were observed under a microscope to confirm the sweet potato stem nematode.

[0091] 2) Use 1ml of 100mg l -1 Disinfect with streptomycin sulfate (Str) for 15 minutes, and gently shake repeatedly to ensure that the nematodes and Str are fully mixed and in contact.

[0092] 3) Centrifuge at 5000 rpm for 2 min at room temperature, discard the streptavidin, and wash three times with sterile water, centrifuging at 5000 rpm for 2 min each time at room temperature. Store the collected nematodes in sterile water at 4℃.

[0093] 4) Take 10 μl of nematodes and dilute them 10 times with 90 μl of water. Count them under a microscope and repeat 3 times to determine the concentration of collected nematodes. The total number of female nematodes, male nematodes and larvae is taken as the nematode quantity.

[0094] 5) Wash the surface of the transgenic sweet potato tubers and wild-type sweet potato tubers with tap water to remove the soil, and then disinfect the surface by washing the tubers with 70% ethanol. Take 3 tubers from each line as replicates.

[0095] 6) Use a hole punch to make a hole in the middle of the sweet potato tuber. Inject 250 sweet potato stem nematodes into the hole using a nozzle. Insert the potato strip from the hole punch into the hole and seal it with molten paraffin. Incubate at 25℃ for 45 days.

[0096] (2) Identification by inoculation with stem nematodes indoors

[0097] After 45 days of inoculation and culture, cross-sections were cut along the inoculation holes to observe and count the weight loss rate and diseased area of ​​transgenic sweet potato tubers and wild-type sweet potato tubers.

[0098] The method for identifying sweet potato stem nematode resistance was based on Xie Yiping et al. (2002). The infected area was graded, and the resistance of transgenic lines was determined according to the disease index.

[0099] The severity of disease in potato tubers is graded based on the degree of disease on the cross-section of the tuber, as detailed below:

[0100] Level 0: No symptoms;

[0101] Grade 1: The affected area accounts for less than 25% of the cross-section;

[0102] Grade 2: The affected area accounts for 25%-50% of the cross-section;

[0103] Grade 3: The affected area accounts for 50%-75% of the cross-section;

[0104] Grade 4: The affected area accounts for more than 75% of the cross-section.

[0105] Results of indoor stem nematode inoculation of transgenic sweet potato tubers and wild-type sweet potato tubers (control) are as follows: Figure 3 As shown in Figure A, the wild-type control plants were completely infected by nematodes, while the transgenic sweet potato lines showed a certain degree of improved nematode resistance.

[0106] The root weight loss rates of wild-type control plants and transgenic sweet potato L1 and L2 were 18.87%, 6.85%, and 6.79%, respectively. Figure 3 (B); the percentages of diseased area in cross-sections of wild-type control plants, transgenic sweet potato L1 and L2 tubers were 41.36%, 6.763%, and 12.99%, respectively. Figure 3 (C); In summary, the wild-type control plants were completely infected with nematodes and were highly susceptible, while the transgenic sweet potatoes L1 and L2 were resistant (R). The results indicate that introducing the IbMYB4 gene can improve the resistance of sweet potatoes to stem nematode disease.

[0107] (3) Determination of lignin content

[0108] The lignin content of IbMYB4 transgenic sweet potato tubers in step (2) after inoculation with stem nematodes was detected using a lignin content kit (Suzhou Keming Biotechnology Co., Ltd., catalog number: MZS-1-G). Wild-type sweet potato tubers (Lizixiang variety) were used as a control (WT). The experiment was repeated three times, and the average value was taken.

[0109] The experimental results are shown in Figure 3 The results showed that the lignin content of IbMYB4 transgenic sweet potato L1 and L2 was significantly higher than that of the control plant.

[0110] In summary, the wild-type control plants were completely infected with nematodes and were highly susceptible, while the transgenic sweet potato plants L1 and L2 were resistant (R). These results indicate that introducing the IbMYB4 gene can improve the resistance of sweet potato to stem nematode disease.

[0111] In summary, overexpression of the IbMYB4 gene enhances the resistance of sweet potato to stem nematode disease.

[0112] The present invention has been described in detail above. For those skilled in the art, the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. Although specific embodiments have been given, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein. Some of the essential features can be applied within the scope of the following appended claims.

Claims

1. Application of IbMYB4 protein in improving resistance to sweet potato stem nematode disease; The IbMYB4 protein is a protein of type A1 or A2 as follows: A1. The amino acid sequence is the protein that is the amino acid sequence shown in SEQ ID No. 2 of the sequence listing; A2, a fusion protein obtained by attaching a protein tag to the N-terminus and / or C-terminus of A1).

2. The application according to claim 1, characterized in that: The IbMYB4 protein is derived from sweet potato.

3. The application of a substance that increases the expression level of the gene encoding the IbMYB4 protein as described in claim 1 in improving resistance to sweet potato stem nematode disease; wherein the substance that increases the expression level of the gene encoding the IbMYB4 protein is a nucleic acid molecule encoding the IbMYB4 protein as described in claim 1.

4. The application according to claim 3, characterized in that: The IbMYB4 protein is derived from sweet potato.

5. The application according to claim 4, characterized in that: The coding sequence of the nucleic acid molecule is the nucleic acid molecule with SEQ ID No. 1 in the sequence listing.

6. A method for improving the resistance of sweet potatoes to stem nematodes, characterized in that: The method includes step M, which is to enhance, increase, or upregulate the expression level of the gene encoding the IbMYB4 protein of claim 1, so as to improve the resistance of sweet potato to stem nematodes.

Images