Application of SCAB82331 gene or protein coded by SCAB82331 gene in regulation and control of synthesis of thaxtomin A

Abstract

The invention discloses an application of an SCAB82331 gene or a protein coded by the SCAB82331 gene in regulation and control of synthesis of thaxtominA, and belongs to the technical field of gene engineering. According to the application disclosed by the invention, the SCAB82331 gene in the streptomyces scabies is deleted through a genetic engineering way, so that the high-yield strain of the thaxtominA is obtained, and the yield of the thaxtominA in the streptomyces scabies is increased. When the SCAB82331 gene is deleted in the streptomyces scabies, the yield of the thaxtominA is obviously increased by 66.2%; after the SCAB82331 gene is supplemented in the delta SCAB82331 mutant strain, the yield of the thaxtominA is recovered, and the yield of the thaxtominA is recovered; the deletion of the SCAB82331 gene can be used for directionally improving the biosynthesis yield of the thaxtominA in streptomyces scabies.

Description

Technical Field

[0001] The present invention relates to the field of genetic engineering technology, and particularly to the application of the SCAB_82331 gene or the protein encoded thereby in regulating the synthesis of thaxtomin A. Background Art

[0002] Streptomyces is a type of Gram-positive bacteria widely present in soil. The most remarkable feature of Streptomyces is its strong secondary metabolic ability, capable of producing a variety of bioactive substances such as antibiotics, enzymes, and plant growth regulators. These metabolites have important application values in the fields of medicine, agriculture, etc. In recent years, with the increasing attention to environmental protection and sustainable development, the research and development of biogenic pesticides have received growing attention. As a secondary metabolite produced by Streptomyces, thaxtonin A exhibits significant herbicidal activity and is expected to become an ideal alternative to traditional chemical herbicides. Thaxtonin A belongs to polyketide compounds. Its molecular structure contains multiple active groups, endowing it with unique herbicidal activity. Thaxtonin A mainly exerts its herbicidal effect by interfering with plant cell wall synthesis and inhibiting photosynthesis. Research shows that thaxtonin A can specifically act on certain weeds with less impact on crops and the environment.

[0003] The thaxtomin A biosynthetic gene cluster is about 18 kb long and contains 7 genes (txtR, txtA, txtB, txtE, txtD, txtC, and txtH). Among them, txtR encodes the positive regulator txtR in the thaxtomin A biosynthetic pathway, and this protein activates the biosynthesis of thaxtomin by acting on the promoter regions of txtA and txtE.

[0004] Lrp family proteins (Leucine-responsive regulatory proteins) are a class of transcriptional regulators widely present in bacteria, mainly involved in regulating various metabolic pathways and stress responses. Lrp family proteins play a central role in the metabolic regulation of bacteria. They can respond to the nutritional status inside and outside the cell, especially the change in the concentration of amino acids, thereby regulating the expression of related genes. Lrp activates or inhibits the transcription of these genes by binding to the promoter region of the target gene, thus finely regulating the metabolic pathway. There is very little research on increasing the yield of thaxtomin A by regulating genetic engineering means in Streptomyces scabiei. Summary of the Invention

[0005] The object of the present invention is to provide the application of the SCAB_82331 gene or the protein encoded thereby in regulating the synthesis of thaxtomin A, so as to solve the problems existing in the above-mentioned prior art. The present invention discovers that after the deletion of the SCAB_82331 gene, the yield of thaxtomin A in Streptomyces scabies is significantly increased, confirming that SCAB_82331 is a negative regulator involved in the biosynthesis of thaxtomin A.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is the application of the SCAB_82331 gene or the protein encoded thereby in regulating the synthesis of thaxtomin A.

[0008] Another technical solution of the present invention is the application of a recombinant vector, expression cassette, transgenic cell line or recombinant bacterium containing the SCAB_82331 gene in increasing the synthesis of thaxtomin A.

[0009] Still another technical solution of the present invention is the application of a recombinant vector, expression cassette, transgenic cell line or recombinant bacterium containing the SCAB_82331 gene in cultivating an engineered bacterium with high yield of thaxtomin A.

[0010] One of the technical solutions of the present invention is an engineered bacterium with high yield of thaxtomin A, and the engineered bacterium is a ΔSCAB_82331 deletion mutant of Streptomyces scabies 87.22.

[0011] Another technical solution of the present invention is a method for cultivating an engineered bacterium with high yield of thaxtomin A. In the starting strain, the SCAB_82331 gene is silenced or knocked out, or the level of the protein encoded thereby is down-regulated to promote the synthesis of thaxtomin A.

[0012] Based on the above technical solutions, the present invention has the following technical effects:

[0013] The negative regulatory gene SCAB_82331 for thaxtomin A biosynthesis was identified in this invention. By deleting the SCAB_82331 gene in Streptomyces scabies through genetic engineering, a high-yield strain of thaxtomin A was obtained, increasing the production of thaxtomin A in Streptomyces scabies and providing technical support for improving the fermentation production of thaxtomin A in industrial production. When the SCAB_82331 gene was deleted in Streptomyces scabies, the production of thaxtomin A increased significantly by 66.2%. After the SCAB_82331 gene was complemented in the ΔSCAB_82331 mutant strain, the production of thaxtomin A was restored. This indicates that SCAB_82331 is a negative regulatory factor involved in thaxtomin A biosynthesis, and the deletion of the SCAB_82331 gene can be used to directionally increase the biosynthesis yield of thaxtomin A in Streptomyces scabies. Brief Description of the Drawings

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 It is the position information of the SCAB_82331 gene and its adjacent genes on the chromosome of Streptomyces scabies.

[0016] Figure 2 It is a schematic diagram for constructing a deletion mutant using the suicide plasmid pUCTSR and homologous recombination technology.

[0017] Figure 3 It is a schematic diagram for PCR verification of the ΔSCAB_82331 deletion mutant. Among them, 1 represents the positive control of 1660 bp, 2 represents the negative control of 492 bp, 3 represents that the PCR cloning amplification band of the positive clone is the same size as 1, and M represents the 5000 bp DNA Marker.

[0018] Figure 4 It is an analysis chart of the production of thaxtomin A in the fermentation products of related strains such as the original strain 87.22 of Streptomyces scabies and the ΔSCAB_82331 deletion mutant.

[0019] Figure 5 It is an analysis chart of the biomass of the ΔSCAB_82331 deletion mutant.

[0020] Figure 6It is an analysis diagram of the spore growth of the ΔSCAB_82331 deletion mutant strain. Specifically, it includes the sporulation of the original strain Streptomyces scabies 87.22, the deletion mutant strain ΔSCAB_82331, the complemented strain ΔSCAB_82331 / pIB-82331 and its empty vector control strain ΔSCAB_82331 / pIB139 on the SFM plate. Among them, A is the sporulation situation on the 1st day, B is the sporulation situation on the 3rd day, and C is the sporulation situation on the 5th day.

[0021] Figure 7 It is the transcriptional analysis of the genes related to thaxtomin A biosynthesis in the original strain Streptomyces scabies 87.22 and the ΔSCAB_82331 deletion mutant strain. Specifically, it includes the 24h and 48h transcriptional analysis of the thaxtomin A biosynthesis genes txtR(A), txtA(B), and txtE(C).

[0022] Figure 8 It is the EMSA analysis of the SCAB_82231 encoded protein and the promoter region of the genes related to thaxtomin A biosynthesis. Detailed implementation manners

[0023] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be regarded as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0024] It should be understood that the terms described in the present invention are only for describing particular implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0025] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0026] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the specification of the present invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of this application are merely exemplary.

[0027] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0028] The technical solutions of the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are all purchased from commercial channels or have been made public.

[0029] The embodiments of the present invention provide the application of the SCAB_82331 gene or the protein encoded thereby in regulating the synthesis of thaxtomin A.

[0030] In some specific embodiments, the nucleotide sequence of the SCAB_82331 gene is as shown in SEQ ID NO.1; the amino acid sequence of the protein encoded thereby is as shown in SEQ ID NO.2.

[0031] In some specific embodiments, overexpressing the SCAB_82331 gene or upregulating the level of the protein encoded thereby reduces the synthesis of thaxtomin A; silencing or knocking out the SCAB_82331 gene or downregulating the level of the protein encoded thereby promotes the synthesis of thaxtomin A.

[0032] The embodiments of the present invention also provide the application of a recombinant vector, expression cassette, transgenic cell line or recombinant bacterium containing the SCAB_82331 gene in enhancing the synthesis of thaxtomin A.

[0033] The embodiments of the present invention also provide the application of a recombinant vector, expression cassette, transgenic cell line or recombinant bacterium containing the SCAB_82331 gene in cultivating an engineered bacterium with high yield of thaxtomin A.

[0034] The embodiments of the present invention also provide an engineered bacterium with high yield of thaxtomin A, and the engineered bacterium is a ΔSCAB_82331 deletion mutant strain of Streptomyces scabies 87.22.

[0035] The embodiments of the present invention also provide a method for cultivating an engineered bacterium with high yield of thaxtomin A. In the starting strain, the SCAB_82331 gene is silenced or knocked out or the level of the protein encoded thereby is downregulated to promote the synthesis of thaxtomin A.

[0036] In some specific embodiments, the starting strain includes Streptomyces scabies 87.22.

[0037] In some specific embodiments, a recombinant vector, expression cassette, transgenic cell line or recombinant bacterium of the SCAB_82331 gene is used to silence or knockout the SCAB_82331 gene and down-regulate the protein level encoded thereby.

[0038] In the present invention, the SCAB_82331 gene is first deleted in Streptomyces scabies through genetic engineering to obtain a high-yield strain of Streptomyces scabies thaxtomin A, and then the obtained corresponding high-yield engineering strain of Streptomyces scabies thaxtomin A is used for fermentative production of thaxtomin A; wherein, the nucleotide sequence of the SCAB_82331 gene is as shown in SEQ ID NO.1, and the amino acid sequence encoded by the nucleotide sequence is as shown in SEQ ID NO.2.

[0039] In the step of deleting the SCAB_82331 gene in Streptomyces scabies, the specific Streptomyces scabies used is the strain Streptomyces scabies 87.22, and the deletion of the gene is achieved through the suicide plasmid pUCTSR and homologous recombination technology.

[0040] The SCAB_82331 gene belongs to the Lrp (leucine-responsive regulatory protein) family of transcriptional regulatory proteins.

[0041] The strain Streptomyces scabies 87.22 is a publicly available strain provided by the China General Microbiological Culture Collection Center, and the deposit number is CGMCC 4.1765.

[0042] The SCAB_82331 gene deletion mutant of Streptomyces scabies enhances the synthesis of thaxtomin A and is used as a herbicide.

[0043] The strains and plasmids used in the examples of the present invention are shown in Table 1, and the primer sequences used are shown in Table 2.

[0044] Table 1 Strains and plasmids used in the examples of the present invention

[0045]

[0046] Table 2 Primers used in the examples of the present invention

[0047]

[0048]

[0049] The Escherichia coli used in the embodiments of the present invention was cultured at 37°C in liquid LB medium or on an LB solid plate supplemented with 2.0% agar. Streptomyces scabies 87.22 was cultured at 28°C in TSB medium or on an SFM solid plate containing 2% agar. The medium used for Streptomyces scabies to ferment and produce thaxtomin A was OBB liquid fermentation medium, and it was cultured at 28°C. The general operation techniques for Escherichia coli and Streptomyces scabies were carried out according to standard operations. The synthesis of primers and DNA sequencing were completed by General Biosystems (Anhui) Co., Ltd.

[0050] Example 1

[0051] Information related to the SCAB_82331 gene:

[0052] For the location information of the SCAB_82331 gene and its adjacent genes on the chromosome of Streptomyces scabies, see Figure 1 .

[0053] The nucleotide sequence of the SCAB_82331 gene is shown in SEQ ID NO.1, and the encoded amino acid sequence is shown in SEQ ID NO.2.

[0054] SEQ ID NO.1: ATGGCCGTGGACGAGCTCGACACGCGCATCCTGCGGCTGCT GCTGGACCGGCCGCGCACCAGCGTGCGGGAGTACGCCCGCATCCTCGGCGTCGCCCGTGGCACGCTGCAGGCCCGCCTCGACCGGCTGGAACGCGAGGGCGTGATCACGGGCACCGGGCCGTCCCTCTCCCCCGCCGCGCTGGGCCACCCCGTGCTGGCGTTCGTGCACATCGAGGTGACCCAGGGGCATCTGGACGACGTGGGGGACGCGCTGGCGGCCGTACCGGAGATCGTCGAGGCCTTCTCGATCACCGGCGGCGGCGATCTCCTGACCCGGGTCGTGGCCCGGGACAACGCGCACCTGGAGGACGTCATCCAGGCACTGATCAGCCTTCCGGGCGTCGTGCGCACCCGCACGGAGGTCGCGCTCAGGGAACGGGTGCCCCACCGGCTGTCACCGCTGGTGGAGTCGATCGGCGCGGCGGCGGCCCGGTCGGCGGCGCGGAACTGA;

[0055] SEQ ID NO.2: MAVDELDTRILRLLLDRPRTSVREYARILGVARGTLQARLDRLE REGVITGTGPSLSPAALGHPVLAFVHIEVTQGHLDDVGDALAAVPEIVEAFSITGGGD LLTRVVARDNAHLEDVIQALISLPGVVRTRTEVALRERVPHRLSPLVESIGAAAARSA ARN。

[0056] Example 2

[0057] Construction of the ΔSCAB_82331 deletion mutant strain (see Figure 2 ):

[0058] Using the Streptomyces scabies genome as a template, and 82331-UF / R and 82331-DF / R as primers, 1500 bp homologous fragments upstream and downstream of the partial SCAB_82331 gene were amplified by PCR. The target fragments were recovered, and the upstream and downstream fragments were double-digested with HindIII / XbaI and KpnI / EcoRI respectively. After recovering the target fragments by agarose gel electrophoresis, they were cloned into the pUCTSR plasmid to obtain the recombinant plasmid pUCTSR-ΔSCAB_82331, and the pUCTSR-ΔSCAB_82331 was verified by double digestion. The specific primer sequences are shown in Table 2. Among them, the underlined sequences of "AAGCTT", "TCTAGA", "GGTACC" and "GAATTC" are the cleavage sites of the restriction enzymes HindIII, XbaI, KpnI and EcoRI respectively.

[0059] The constructed recombinant plasmid was transferred into Escherichia coli ET12567(pUZ8002), and the plasmid pUCTSR-ΔSCAB_82331 was transformed into Streptomyces scabies 87.22 by the intergeneric conjugation transfer technique. Thiostrepton was used to screen for resistant positive mutant strains, and the picked strains were analyzed by PCR with the primers 82331-CF / R. The positive strain with successful verification was named ΔSCAB_82331( Figure 3 ).

[0060] Example 3

[0061] Construction of the complemented strain and the empty vector complemented strain:

[0062] Using the Streptomyces scabies genome as a template, the complete SCAB_82331 gene fragment was amplified by PCR with primers 82331-CF / R. Meanwhile, EcoRI and NdeI restriction enzyme sites were introduced at both sides. The PCR product was recovered by agarose gel and cloned into the pIB139 plasmid to obtain the recombinant plasmid pIB-82331, which was verified by double enzyme digestion. The specific primer sequences are shown in Table 2. Among them, the underlined sequences "CATATG" and "GAATTC" are the restriction enzyme sites of restriction endonucleases NdeI and EcoRI, respectively.

[0063] The recombinant plasmid pIB-82331 and the empty plasmid pIB139 were transformed into the competent cells of ET12567(pUZ8002). After conjugation transfer, they were respectively introduced into the deletion mutant ΔSCAB_82331. The conjugants with resistance were screened with apramycin. After PCR verification, the correct complemented strain ΔSCAB_82331 / pIB-82331 and the empty plasmid control strain ΔSCAB_82331 / pIB139 were obtained.

[0064] Example 4

[0065] Detection of the yield of thaxtomin A in a series of Streptomyces scabies strains:

[0066] The spores of Streptomyces scabies 87.22 and the ΔSCAB_82331 series strains with the same growth on the plate were inoculated into a TSB seed bottle. The shaker was set at a temperature of 28 °C and a rotation speed of 220 rpm for oscillation culture for 2 days, and then transferred to an OBB liquid medium for continuous oscillation culture for 7 days. After the fermentation was completed, thaxtomin A in the fermentation broth was extracted and analyzed by HPLC, and the yield was calculated using the thaxtomin A standard curve.

[0067] Example 5

[0068] Transcriptional analysis of genes related to thaxtomin A biosynthesis in Streptomyces scabies 87.22 and ΔSCAB_82331:

[0069] Using an RNA extraction kit, RNA was extracted from Streptomyces scabies 87.22 and the mutant ΔSCAB_82331 during the fermentation process. After reverse transcription into cDNA, the transcriptional levels of genes related to thaxtomin A biosynthesis were analyzed by real-time fluorescence quantitative PCR.

[0070] Example 6

[0071] EMSA analysis of the SCAB_82331 protein and the promoter region of genes related to thaxtomin A biosynthesis:

[0072] Using the genomic DNA of Streptomyces scabii as a template and pET-82331F / R as primers, PCR amplified the complete SCAB_82331 gene fragment, and after double digestion with NdeI and EcoRI, cloned into the pET28a plasmid to obtain the recombinant plasmid pET28a-82331. The specific primer sequences are shown in Table 2, where the underlined "CATATG" and "GAATTC" sequences are the restriction endonuclease cutting sites of NdeI and EcoRI, respectively.

[0073] pET28a-82331 was transformed into competent E. coli BL21 (DE3) to obtain protein expression strain BL21 / pET-82331. The SCAB_82331 protein was successfully expressed and isolated and purified using inducer IPTG and nickel column affinity chromatography.

[0074] Using the genome of Streptomyces scabii as a template, txtA-EF / R, txtE-EF / R and txtR-EF / R were used as primers to PCR amplify the promoter regions of txtA, txtE and txtR genes. After recovery by agarose gel electrophoresis, they were named PtxtA, PtxtE and PtxtR probes respectively. The total volume of the EMSA system of different concentrations of SCAB_82331 protein combined with 200ng DNA probe was 20μL. After fully mixing, it was placed in a 30℃ incubator for incubation for 10-20min. After the incubation, the whole system was spotted onto the wells of 6% active PAGE gel for electrophoresis.

[0075] Analysis of specific experimental results of the above embodiments:

[0076] 1. The production of thaxtomin A was significantly increased after the SCAB_82331 gene was deleted

[0077] Construction process of SCAB_82331 gene deletion mutant strain ΔSCAB_82331 ( Figure 2 ) and PCR validation ( Figure 3 ) As shown in the figure. ΔSCAB_82331 was fermented in OBB liquid medium for 7 days, and the thaxtomin A production of the original strain 87.22 was increased by 66.2% by HPLC analysis. Figure 4 ), indicating that the SCAB_82331 gene is negatively regulated by thaxtomin A biosynthesis. During the fermentation process, the fermented bacteria were sampled and the biomass was measured every day. The results showed that there was almost no difference in the biomass of the mutant strain ΔSCAB_82331 and the original strain 87.22 ( Figure 5) It shows that the deletion of SCAB_82331 has little effect on the growth of the bacterial cells, that is, the effect of the deletion of SCAB_82331 on the production of thaxtomin A is not caused by affecting the growth of the bacterial cells.

[0078] 2. Complementation of the SCAB_82331 gene

[0079] To determine that the phenotype of the mutant strain ΔSCAB_82331 is completely caused by the gene mutation of SCAB_82331, the present invention constructs a complementation experiment of the SCAB_82331 gene. The complementation plasmid pIB-82331 uses the strong promoter PermE* of the erythromycin resistance gene to initiate the transcriptional expression of the SCAB_82331 gene and is used for the complementation of the mutant strain ΔSCAB_82331. Through fermentation and HPLC analysis, the production of thaxtomin A in the complemented strain ΔSCAB_82331 / pIB-82331 is restored to the same level as that of the original strain 87.22.

[0080] 3. Deletion of the SCAB_82331 gene does not affect the morphological differentiation of the strain

[0081] To clarify whether the SCAB_82331 gene affects the formation of spores of the strain, the original strain 87.22 and the ΔSCAB_82331 series of strains are simultaneously spread on the SFM plate and incubated upside down in an incubator at 28 °C to observe the growth of spores. The results show that, compared with the original strain 87.22, the spore formation of the mutant strain ΔSCAB_82331 is significantly advanced ( Figure 6 ), indicating that the deletion of SCAB_82331 can significantly promote the spore formation of Streptomyces scabiei.

[0082] 4. SCAB_82331 negatively regulates the transcription of genes related to thaxtomin A biosynthesis

[0083] The results of qRT-PCR prove that, compared with the starting strain 87.22, the expression levels of the genes txtR, txtA, and txtE related to thaxtomin A biosynthesis in the mutant strain ΔSCAB_82331 are all significantly increased ( Figure 7 ), indicating that the deletion of the SCAB_82331 gene can cause a significant increase in the transcriptional levels of genes related to thaxtomin A biosynthesis, thereby increasing the production of thaxtomin A.

[0084] 5. The SCAB_82331 protein directly binds to the promoters of related genes

[0085] The results of EMSA showed that, compared with the control without added protein, obvious in vitro binding effects of SCAB_82331 with each probe DNA occurred after the addition of SCAB_82331 protein ( Figure 8 ), indicating that SCAB_82331 protein can directly regulate the biosynthesis of thaxtomin A.

[0086] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. Use of the SCAB_82331 gene or the protein encoded thereby in regulating the synthesis of thaxtomin A.

2. The application according to claim 1, wherein The nucleotide sequence of the SCAB_82331 gene is shown as SEQ ID NO.1; the amino acid sequence of the protein encoded thereby is shown as SEQ ID NO.

2.

3. The application according to claim 1, characterized in that Overexpression of the SCAB_82331 gene or upregulation of the level of the protein encoded thereby reduces the synthesis of thaxtomin A; silencing or knocking out the SCAB_82331 gene or downregulating the level of the protein encoded thereby promotes the synthesis of thaxtomin A.

4. Use of a recombinant vector, expression cassette, transgenic cell line or recombinant bacterium containing the SCAB_82331 gene in enhancing the synthesis of thaxtomin A.

5. Use of a recombinant vector, expression cassette, transgenic cell line or recombinant bacterium containing the SCAB_82331 gene in cultivating an engineered bacterium with high yield of thaxtomin A.

6. An engineered bacterium with high yield of thaxtomin A, characterized in that, The engineered bacterium is a ΔSCAB_82331 deletion mutant of Streptomyces scabies 87.

22.

7. A method for cultivating an engineered bacterium with high-yield thaxtomin A, characterized in that, In the starting strain, silencing or knocking out the SCAB_82331 gene or downregulating the level of the protein encoded thereby promotes the synthesis of thaxtomin A.

8. The method according to claim 7, wherein The starting strain includes Streptomyces scabies 87.

22.

9. The method according to claim 7, wherein Using a recombinant vector, expression cassette, transgenic cell line or recombinant bacterium of the SCAB_82331 gene to silence or knock out the SCAB_82331 gene and downregulate the level of the protein encoded thereby.

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