Application of SlSRC2 gene in regulation and control of broad-spectrum disease resistance of tomatoes

Abstract

The invention provides application of an SlSRC2 gene in regulation and control of tomato broad-spectrum disease resistance, AtSRC2 in arabidopsis thaliana is retrieved through NCBI (National Center of Biotechnology Information), BLAST analysis is performed in a tomato genome by using an amino acid sequence of the AtSRC2, and a protein, namely the SlSRC2, which has the highest similarity with the AtSRC2 in tomatoes is found. Through overexpression of the CDS region of the SlSRC2 in the tomato, the purpose of overexpression of the SlSRC2 is achieved, the alkaloid content in the tomato can be reduced, and the resistance to botrytis cinerea, phytophthora infestans and tomato yellow leaf curl virus is weakened; on the other hand, gene editing is conducted on the specific sequence of the SlSRC2 gene in the tomato by means of the CRISPR-Cas9 technology, the alkaloid content of the obtained mutant plant can be increased, and the resistance of the mutant plant to botrytis cinerea, phytophthora infestans and tomato yellow leaf curl virus is enhanced.

Description

Technical Field

[0001] This invention belongs to the field of biotechnology, specifically relating to a... SlSRC2 Application of genes in regulating broad-spectrum disease resistance in tomatoes. Background Technology

[0002] Tomatoes are a favorite horticultural product among global consumers, making a significant contribution to human health. However, tomato production is often threatened by various pathogens, such as bacteria, fungi, oomycetes, nematodes, and plant viruses, causing substantial losses in yield and quality. Among these, the necrotrophic fungus *Botrytis cinerea*, the semi-biotrophic oomycete *Phytophthora blight*, and tomato yellow leaf curl virus have become several important pathogens harming tomato production. Currently, chemical and biological control methods are mainly used to manage these diseases. Chemical control, primarily using pesticides, can reduce disease occurrence to some extent, but it leads to pesticide residues and environmental pollution. Biological control utilizes microbial agents and plant inducers, leveraging beneficial microorganisms to antagonize and regulate pathogens, but it also faces challenges such as limited and unstable control effects. Therefore, introducing broad-spectrum disease-resistant genes into tomato breeding is essential and the most effective approach.

[0003] Current research on broad-spectrum disease resistance in plants has yielded some results in field crops such as rice, wheat, and corn. However, there are relatively few broad-spectrum disease resistance genes in tomatoes that can be applied to breeding. Therefore, identifying broad-spectrum disease resistance genes in tomatoes can provide a molecular basis for tomato breeding and promote the application of molecular breeding research for broad-spectrum disease resistance. Summary of the Invention

[0004] In view of this, the present invention provides a SlSRC2 The application of genes in regulating broad-spectrum disease resistance in tomatoes, through gene editing and knockout in tomatoes. SlSRC2 This increases the alkaloid content in the plant, thereby enhancing the tomato's resistance to various pathogens. Conversely, overexpression in tomatoes... SlSRC2 Afterwards, its resistance does not change significantly or may even decrease.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a SlSRC2 Application of genes in regulating broad-spectrum disease resistance in tomatoes.

[0006] In the above technical solution, this invention retrieves AtSRC2 from Arabidopsis thaliana using NCBI, and then performs BLAST analysis on its amino acid sequence in the tomato genome to find the protein in tomato with the highest similarity to it, namely... SlSRC2 The amino acid sequence of AtSRC2 is shown in the sequence listing SEQ ID NO: 1. SlSRC2 The cDNA sequence is shown in the sequence listing SEQ ID NO: 2. SlSRC2 The amino acid sequence is shown in the sequence listing SEQ ID NO: 3; by SlSRC2 The CDS region is overexpressed in tomatoes, achieving the effect of... SlSRC2 The purpose of overexpression is to reduce the alkaloid content in tomatoes, thereby weakening their resistance to Botrytis cinerea, Late Blight, and Tomato Yellow Leaf Curl Virus; on the other hand, this invention utilizes CRISPR-Cas9 technology to target alkaloids in tomatoes... SlSRC2 Gene editing of specific gene sequences can produce mutant plants that have increased alkaloid content and enhanced resistance to botrytis cinerea, late blight, and tomato yellow leaf curl virus.

[0007] Preferably, the spectrum of disease resistance includes resistance to gray mold, late blight, and tomato yellow leaf curl virus.

[0008] Preferably, gene editing is used to knock out the gene in tomatoes. SlSRC2 Genes can enhance the broad-spectrum disease resistance of tomatoes.

[0009] Preferably, the SlSRC2 Gene insertion into tomatoes SlSRC2 Overexpression of genes to reduce the resistance of tomatoes to gray mold, late blight, and yellow leaf curl virus.

[0010] Preferably, the step of achieving overexpression is: isolating and cloning from tomatoes SlSRC2 Genes, utilizing the aforementioned SlSRC2 Gene overexpression vectors were constructed and introduced into the cells or tissues of tomatoes.

[0011] Preferably, the overexpression vector is introduced into tomatoes by introducing the overexpression vector into tomato cells or tissues through Agrobacterium-mediated genetic transformation.

[0012] Preferably, SlSRC2 The nucleotide sequence of the gene is any of the following: a. Has a nucleotide sequence as shown in SEQ ID NO:2; b. A complementary nucleotide sequence to the nucleotide sequence shown in SEQ ID NO:2; c. A sequence that has more than 90% homology with the nucleotide sequence shown in SEQ ID NO:2; d. A nucleotide sequence that encodes the same protein as a, b, and c, but is different from them due to the degeneracy of the genetic code.

[0013] Preferably, SlSRC2 The amino acid sequence encoded by the gene is shown in SEQ ID NO:3.

[0014] Secondly, the present invention provides a product containing the aforementioned SlSRC2 overexpression vectors of gene nucleotide sequences.

[0015] Thirdly, the present invention provides an engineered bacterium containing the aforementioned overexpression vector.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The genetically modified tomatoes of the present invention have greatly improved resistance to gray mold, late blight and tomato yellow leaf curl virus, which saves production costs, protects the environment, and can effectively improve the post-harvest quality of tomatoes. They are especially suitable for cultivation in facility environment conditions.

[0017] (2) The present invention uses transgenic methods to obtain resistant plants, which is economical, direct and effective, solves the problem of scarce germplasm resources and greatly shortens the breeding cycle. Attached Figure Description

[0018] Figure 1 As provided in 3.1 of Embodiment 3 of the present invention SlSRC2 Diagram illustrating the construction process of a vehicle for expressing justice (excessive quantity); Figure 2 This is a diagram illustrating the gene editing vector construction process provided in 3.2 of Embodiment 3 of the present invention; Figure 3 The embodiment provided in embodiment 5 of the present invention SlSRC2 Image showing expression levels and protein levels in positive (overexpression) plants; Figure 4 As provided in Embodiment 6 of the present invention SlSRC2 A comparison diagram of gene editing in gene-edited plants; Figure 5 This is a statistical chart showing the disease incidence and lesion area of ​​the transgenic material detached leaves inoculated with Botrytis cinerea, provided in 7.1 of Example 7 of the present invention; Figure 6 This is a statistical chart showing the disease incidence and lesion area of ​​the transgenic material leaves inoculated with Late Blight pathogens, provided in section 7.2 of Example 7 of the present invention. Figure 7 The graph shows the disease incidence and virus accumulation in tomato yellow leaf curl virus-inoculated plants of the transgenic material provided in 7.3 of Example 7 of this invention. Figure 8 The graph shows the detection of alkaloid content in the transgenic material provided in Example 8 of this invention after inoculation with Botrytis cinerea and tomato yellow leaf curl virus. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention.

[0020] The present invention will now be described in more detail with reference to specific embodiments. Based on the following description and these embodiments, those skilled in the art can determine the essential features of the invention, and various changes and modifications can be made to the invention to suit various uses and conditions without departing from its spirit and scope.

[0021] Example 1 SlSRC2 Gene cloning and analysis SlSRC2 The process begins by retrieving the amino acid sequence of AtSRC2 (AT1G09070) from NCBI (see SEQ ID NO: 1 in the sequence listing). Then, BLAST is performed on SGN using the AtSRC2 amino acid sequence to identify homologous proteins in tomatoes. SlSRC2 To obtain its sequence number, its cDNA sequence (see SEQ ID NO: 2) and amino acid sequence (see SEQ ID NO: 3) were retrieved from SGN. Primers for amplifying the ORF were designed: the forward primer was (5'-GATGACGATGACAAGGAATTCATGGAGTATCCAACATTAGAC-3') and the reverse primer was (5'-GTCCTTGTAATCCATGAATTCAAAATCAAATCCCCCAACATCA-3'). The full-length ORF was amplified from the background material Ailsa Craig using PCR. SlSRC2 The ORF (open reading frame) sequence was obtained. The amplification method involved first extracting RNA from tomato, then using a reverse transcription kit (purchased from Nanjing Novizan Biotechnology Co., Ltd.) to synthesize the ORF sequence according to the kit's instructions. SlSRC2 The cDNA of the gene was then amplified by PCR to obtain the required ORF fragment. The fragment was then recovered using a 1% agarose gel electrophoresis kit (OMEGA, see the instruction manual for specific procedures) after PCR detection.

[0022] The amplification reaction system is as follows: 2*Phanta Max Buffer 25μL dNTP Mix (10mM each) 1μL SlSRC2-OE-FW (10μM) 2μL SlSRC2-OE-RV (10μM) 2μL Phanta Max Super-Fidelity DNA Polymerase1μL 1 μL template cDNA ddH2O 18μL The reaction procedure is as follows: Pre-denaturation 95℃ for 3 min Denaturation at 95°C for 15 seconds Annealing at 55℃ for 15 seconds Extend at 72℃ for 1 minute Extend completely at 72℃ for 5 minutes The denaturation, annealing, and extension processes are repeated 38 times.

[0023] Example 2 SlSRC2 Gene editing target design and amplification In this invention, gene function was studied through gene editing, and it was found that... SlSRC2 The edited tomato plants showed increased resistance to gray mold, late blight, and tomato yellow leaf curl virus. SlSRC2 It plays an important role in regulating the broad-spectrum disease resistance of tomatoes.

[0024] Gene editing first involves using (partial) gene information annotated on a gene chip (http: / / solgenomics.net / tomato / ), and then... (The sentence is incomplete and requires more context to translate accurately.) SlSRC2 Cas9 target analysis was performed on the cDNA, and primers with two targets were designed. The primer for the first target was (AATCTAACAGTGTAGTTTGACGTCGTCGTTTCAATCTCGTTTTAGAGCTAGAAATAGC), and the primer for the second target was (CTATTTCTAGCTCTAAAACTCCGGTAAACCCAAAGGTCCAAACTACACTGTTAGATTC). A 608 bp sequence was amplified from the 043 plasmid by PCR. The amplification method was to extract the 043 plasmid using a small-scale method (kit purchased from Beijing TransGen Biotech Co., Ltd., see the instruction manual for specific procedures), and amplify it using a one-step method with the plasmid as a template. The amplification product was then recovered using a recovery kit (purchased from OMEGA, see the instruction manual for specific procedures).

[0025] Example 3: Vector Construction 3.1 Construction of Overexpression Vectors The empty pCAMBIA2300-flag vector was digested with BamHI and StuI. The large fragment of the pCAMBIA2300-flag vector was recovered using 1.0% agarose gel assay. The concentrations of the recovered gene fragment and the large vector fragment were determined using a NaNO Drop 2000 assay. The cloned fragment and vector were mixed at a 1:1 ratio, and 2 µL of 5×Cell Buffer and 1 µL of Exnase II were added. The volume was then adjusted to 10 µL with sterile water. Ligation was performed at 37°C for 30 min. The specific reaction procedure is as follows: Exnase II 1μL 5X CE II Buffer 2μL Linearized cloning vector 25-100 ng Insert fragment amplification product 10-100 ng Add sterile water to a volume of 10 μL Ligation was performed at 37℃ for 30 min. All 10 µL of the ligation product was transformed into *E. coli* TransT1. Positive clones were screened using Kana culture plates, and PCR detection was performed using the reverse primer with the 35S gene. Correctly detected clones were sent to the company for sequencing using the 35S primer. The vector construction process is described in [link to documentation]. Figure 1 .

[0026] The obtained recombinant clones were transformed into Agrobacterium GV3101 using an electroporator at 1800V. Positive clones were selected by screening on LB agar plates containing 100 mg / L Rif and 50 mg / L Kan. The plates were then cultured overnight at 28°C with shaking at 200 rpm. 20 µL of the bacterial culture was collected, resuspended in ddH2O, denatured at 95°C for 10 min, centrifuged at 10000 rpm for 1 min, and 2 µL of the supernatant was used as a template for PCR detection using a 35S forward primer and a gene-specific reverse primer.

[0027] 3.2 Construction of gene editing vectors The PTX plasmid was digested with BsaI (NEB) (37℃, >3h). The digestion product was detected by 1.0% agarose gel extraction and the large PTX fragment (around 18K) was recovered using a recovery kit. The fragment with two target sites was mixed with the vector at a 1:1 ratio, and 1µL of Exnase II, 2µL of 5X Cell Buffer, 25-100ng of linearized cloning vector, and 10-100ng of insert fragment amplification product were added. The volume was then adjusted to 10µL with sterile water. Ligation was performed at 37℃ for 30 min. All ligation products were transformed into E. coli TransT1 using the heat shock method. Positive clones were screened on Kans resistant LB plates, and the bacterial culture was shaken after picking the plaques. PCR detection was performed on the liquid bacterial culture. The pre-primer PTX-FW used for detection was AGCGGATAACAATTTCACACAGGA, and the post-primer PTX-RV used was GCAGGCATGCAAGCTTATTGG. PCR products were detected using 1.0% agarose gel. The empty vector fragment size was 1820 bp, while the vector with dual targets was 1169 bp. The correctly detected bacterial cultures were sent to a sequencing company (Tianyi Huiyuan). Sequence alignment was performed, and the plasmid was extracted using a small-scale method after gentle shaking of the correctly detected bacterial cultures. The vector construction process is detailed below. Figure 2 .

[0028] The obtained recombinant clones were transformed into Agrobacterium GV3101 at 1800V using an electroporator. Positive clones were selected by screening on LB solid plates containing 100mg / L Rif and 50mg / L Kan. The clones were cultured overnight at 28℃ with shaking at 200r / min. 1μL of Agrobacterium solution was used as a template for PCR detection with vector primers.

[0029] Example 4 Genetic Transformation Tomato seeds (Ailsa Craig, hereinafter referred to as A57) were sterilized with sodium hypochlorite for 15 min (with 2% available chlorine) and sown on 1 / 2 MS medium (pH=5.8). They were cultured at 25±2℃ in the dark until germination, then transferred to a photoperiod of 1800 lx, 16 h light / 8 h dark. Cotyledons from 7-8 day old sterile seedlings were pre-cultured for 2 days (MS medium, pH=5.8). The seeds were then resuspended in MS0 to OD... 600Inoculate with ≈0.5% Agrobacterium solution for 3-5 min, blot off excess solution with sterile filter paper, and return to the pre-med medium. Co-culture in the dark for 2 days. Transfer to 1.0 ZR (MS + ZR (zeatin nucleoside) 1.0 mg / L + Cef (cephalosporin) 400 mg / L + Kan (kanamycin) 100 mg / L) for resistance selection. Subculture every two weeks. After resistant shoots appear, transfer explants to 0.2 ZR + Cef (cephalosporin) 200 mg / L + Kan (kanamycin) 100 mg / L. After 20-30 days, cut off the resistant shoots and insert them into rooting medium (RM) to induce rooting. Transplant plants with well-developed root systems into flower pots. See Table 1 for specific medium formulations.

[0030] Table 1. Tomato genetic transformation medium formulation

[0031] Note: Except for MSO, all the above culture media contain 7.4 g / L agar, and the pH of all culture media is 5.8.

[0032] Example 5: In the over-strain SlSRC2 Transcription level and protein expression detection After obtaining transgenic positive plants, we studied the excess lines... SlSRC2 Transcriptional level detection was performed, and two overexpression lines, SlSRC2-flag-4 and SlSRC2-flag-43-6, were identified through quantitative real-time PCR screening. Western blotting further revealed that SlSRC2-flag-4 and SlSRC2-flag-43-6... SlSRC2 Protein expression is consistent with transcriptional levels. See details. Figure 3 .

[0033] Example 6: Detection and Analysis of Gene Editing in Knockout Lines Through genetic transformation, we obtained multiple transformed seedlings and performed gene editing detection on them. The specific procedures are as follows: First, tomato gDNA was extracted using the CTAB method. Gene editing was detected by sequencing the PCR products. Using tomato gDNA as a template, a 322bp amplification was performed, including two target sites. The front primer was 5'-CGCTTGGAGATAAAGATATTG-3', and the back primer was 5'-CCAGAAGCGTAGATCGGAGGC-3'. Detection was performed using 1% agarose gel electrophoresis, and the PCR products were sent for sequencing. By comparing with a reference sequence, three gene-editing positive lines were selected: SlSRC2-KO-3-3, SlSRC2-KO-3-5, and SlSRC2-KO-15-4. See details... Figure 4 .

[0034] Example 7 SlSRC2 Functional identification 7.1 SlSRC2 Identification of resistance to gray mold in transgenic plants To verify SlSRC2 Regarding the function of tomatoes in resisting gray mold, the applicant... SlSRC2 Botrytis cinerea spores were inoculated onto the undersides of mature leaflets from the same part of healthy A57 plants with consistent growth vigor, including those with excess growth, knockout plants, and control plants. The plants were kept at a constant temperature of 22℃, under 16 hours of light / 8 hours of darkness, and 75% relative humidity for 72 hours. The results showed that leaves from the excess growth lines exhibited more severe disease and larger lesion areas; while leaves from the knockout lines showed milder disease and smaller lesion areas. We used ImageJ software to calculate the lesion area and performed statistical analysis on the data. The results indicate that... SlSRC2 The transgenic excess material showed a significant increase in lesion area compared to the wild-type line A57 (see...). Figure 5 ); SlSRC2 The knockout lines showed a significantly smaller lesion area compared to the wild-type A57 line (see...). Figure 5 ).show SlSRC2 Negative regulation of resistance to gray mold.

[0035] 7.2 SlSRC2 Identification of resistance to late blight in transgenic plants To verify SlSRC2 Regarding the function of tomatoes in resisting late blight, the applicant... SlSRC2 For the over-inoculation and knockout plants and the control plant A57, the undersides of mature leaflets from the same part of the compound leaves were inoculated for identification. 10 μL of the treated late blight pathogen was inoculated onto detached leaves. The inoculated leaves were placed in a sealed plastic container with a certain humidity and treated in darkness for 24 hours. After culturing for 5 days under conditions of 16 hours of light and 8 hours of darkness, the area of ​​lesions at the inoculation site was measured. The results showed that leaves from the over-inoculation line exhibited more severe disease and larger lesion areas; while leaves from the knockout line showed milder disease and smaller lesion areas (see...). Figure 6 ).show SlSRC2 Negative regulation of resistance to late epidemic diseases.

[0036] 7.3 SlSRC2 Identification of resistance of transgenic plants to yellow leaf curl virus disease To verify SlSRC2 Regarding the function of tomato resistance to yellow leaf curl virus disease, the applicant tested three-week-old... SlSRC2 Over-inoculation and knockout materials were used for identification of yellow leaf curl virus. The Agrobacterium concentration in TYLCSV was adjusted to OD0.05. 600 =1.0, using the friction inoculation method, inoculate onto the fully expanded leaves of the plant, inoculating 3 leaves per plant. The inoculated material is placed in a 26-degree incubator and cultured for 40 days.

[0037] Inoculation results showed that, compared with the control material A57, the terminal leaves of the over-inoculated material were more curled, and the leaf margins showed deeper yellowing. The knockout material, compared with the control, was healthier and showed milder disease symptoms. RNA was further extracted from the virus-inoculated material and reverse transcribed into cDNA. The expression of TYLCSV was detected using specific primers, with the tomato endogenous actin gene (GenBank accession no. BT013524) used as an internal control. The obtained data were used... The Ct method was used for analysis. The results showed that... SlSRC2 Knockout materials had less viral accumulation, while overabundance materials with obvious symptoms had more viral accumulation (see [link to article]). Figure 7 ).show SlSRC2 Negative regulation of resistance to yellow leaf curl virus disease.

[0038] In summary, the results of the inoculation experiments with the three pathogens indicate that tomatoes SlSRC2 The gene can negatively regulate resistance to gray mold, late blight, and tomato yellow leaf curl virus, making it a promising disease-resistant functional protein for application in tomatoes.

[0039] Example 8 SlSRC2 Detection of alkaloid content in transgenic plants after inoculation with pathogens In order to clarify SlSRC2 Whether the function of negative regulation of broad-spectrum resistance is related to disease-resistance-related compounds alkaloids was investigated. We measured the alkaloid content of plants before and after inoculation with *Botrytis cinerea* and yellow leaf curl virus. The results showed that after inoculation, the alkaloid content of the knockout line was significantly higher than that of the control; while the alkaloid content of the excess material was not significantly different from that of the control (see [link to study].) Figure 8 This indicates that... SlSRC2 The broad-spectrum resistance conferred by knockout materials is achieved by increasing the content of alkaloids in their bodies.

[0040] SEQ ID NO: 1 (AtSRC2 amino acid sequence) MECRSLDLTIISAEDLKDVQLIGKQDLYAVVSINGDARTKQKTKVDKDCGTKPKWKHQMKLTVDDAAARDNRLTLVFEIVADRPIAGDKPVGEVSVPVKELLDQNKGDEEKTVTYAVRLPNGKAKGSLKFSFKFGEKYTYGSSSGPHAPVPSAMDHKTMDQPVTAYPPGHGAPSAYPAPPAGPSSGYPPQGHDDKHDGVYGYPQQAGYPAGTGGYPPPGAYPQQGGYPGYPPQQQGGYPGYPPQGPYGYPQQGYPPQGPYGYPQQQAHGKPQKPKKHGKAGAGMGLGLGLGAGLLGGLLVGEAVSDIADMGDMGDMGDMGGFDF SEQ ID NO: 2 ( SlSRC2 cDNA sequence) SEQ ID NO: 3 (SlSRC2 amino acid sequence) MEYPTLDINVVSGKDLNKVNLITKMDVYVVVSISGADDDRSNQKTKTHVDHDGDNNPTWNFPIKFTIDDSPAVQNRLHLVFKLRCQRALGDKDIGQVEVPIKELLESSNTTKQFVSYQIRKPSGKPKGQLTFSYQFSDKITGNTVVDSKIENPVTAY PAANPPTMVGSTSVYPPIPPPQQGPSGLYPPPPIYASGGSGPAPPPPVAYPPSATAGYPPQPMGYPPVAAGGYGYGYPPVAAYTPPPQYGYPPHQGGHGYGYPQVQRPPKKNNNNMALGLGAGLLGGALGGMIIGDAISDVGGGFDGGFGDVGGFDF.

[0041] Unless otherwise specified, all raw materials used in this invention are existing substances that can be purchased directly from the market.

[0042] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A kind SlSRC2 Application of genes in regulating broad-spectrum disease resistance in tomatoes.

2. The application according to claim 1, characterized in that, Broad-spectrum disease resistance includes resistance to gray mold, late blight, and tomato yellow leaf curl virus.

3. The application according to claim 1, characterized in that, By gene editing to knock out the tomato SlSRC2 Genes can enhance the broad-spectrum disease resistance of tomatoes.

4. The application according to claim 1, characterized in that, Will SlSRC2 Gene insertion into tomatoes SlSRC2 Overexpression of genes to reduce the resistance of tomatoes to gray mold, late blight, and yellow leaf curl virus.

5. The application according to claim 4, characterized in that, The steps to achieve overexpression are: isolating and cloning from tomatoes SlSRC2 Genes, utilizing the aforementioned SlSRC2 Gene overexpression vectors were constructed and introduced into the cells or tissues of tomatoes.

6. The application according to claim 5, characterized in that, The specific method for introducing the overexpression vector into tomatoes is as follows: the overexpression vector is introduced into tomato cells or tissues through Agrobacterium-mediated genetic transformation.

7. The application according to claim 1, characterized in that, SlSRC2 The nucleotide sequence of the gene is any of the following: a. Has a nucleotide sequence as shown in SEQ ID NO:2; b. A complementary nucleotide sequence to the nucleotide sequence shown in SEQ ID NO:2; c. A sequence that has more than 90% homology with the nucleotide sequence shown in SEQ ID NO:2; d. A nucleotide sequence that encodes the same protein as a, b, and c, but is different from them due to the degeneracy of the genetic code.

8. The application according to claim 1, characterized in that, SlSRC2 The amino acid sequence encoded by the gene is shown in SEQ ID NO:

3.

9. Containing the contents of claim 7 SlSRC2 overexpression vectors of gene nucleotide sequences.

10. Engineered bacteria containing the overexpression vector of claim 9.

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