A salt-tolerant Bacillus zanthoxylum bungeanum strain and its application

Abstract

This invention discloses a salt-tolerant Bacillus zanthoxyli strain and its applications, belonging to the field of microbial technology. The Bacillus zanthoxyli RX10 strain of this invention, with the accession number CCTCC M 20242733, integrates multiple functions such as salt tolerance, growth promotion, nitrogen fixation, phosphorus solubilization, potassium solubilization, iron carrier production, indoleacetic acid production, control of grape powdery mildew, and soil improvement. It is a multifunctional plant endophytic bacterium, which is of great significance for promoting growth, preventing disease, and improving soil in saline-alkali conditions.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, specifically to a salt-tolerant Bacillus zanthoxylum bungeanum strain and its applications. Background Technology

[0002] Soil salinization is the process by which soluble salts accumulate in the soil, leading to the deterioration of soil properties and a decline in soil quality. Soil salinization seriously affects agricultural development. When crops are subjected to salt stress, the osmotic pressure and ion homeostasis within the plant are disrupted, resulting in inhibited photosynthesis, slowed growth and development, and metabolic disorders. Ultimately, this leads to reduced crop yield, decreased quality, increased risk of pests and diseases, and in severe cases, even death.

[0003] Plant endophytes are microorganisms that live within the tissues and organs of healthy plants at certain or all stages of their life cycle without causing significant plant diseases. Plant endophytes can improve the osmotic balance and reduce ion toxicity in plant tissues by influencing the plant's antioxidant system, osmotic regulation, mineral element absorption, and photosynthesis, thereby alleviating the damage caused by salt and alkali stress. However, the actual efficacy of microbial inoculants is affected by numerous variables, especially environmental variables, including temperature, humidity, pH, and soil texture. These variables not only challenge the survival and proliferation of the strains but may also interfere with the interaction between the strains and the plant. In saline soils, high salinity is an extreme condition for most microorganisms, and only a very few can adapt. Therefore, screening for microbial strains that can adapt to saline soil environments and function normally under salt stress, promoting growth and disease resistance, is extremely difficult. Summary of the Invention

[0004] In view of the above-mentioned prior art, the purpose of this invention is to provide a salt-tolerant Bacillus zanthoxylum and its applications. This invention isolates a Bacillus zanthoxylum RX10 strain from young grape berries, which can promote plant growth, enhance photosynthesis, reduce plant diseases, and improve plant stress resistance under salt stress.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a strain of Bacillus zanthoxyli RX10, which was deposited on December 5, 2024, at the China Center for Type Culture Collection (CCTC), located at Wuhan University, Bayi Road, Wuchang District, Wuhan City, Hubei Province; its accession number is CCTCC M 20242733.

[0007] The Bacillus zanthoxyli RX10 of the present invention has the following characteristics compared with the previously reported Bacillus zanthoxyli:

[0008] (1) It integrates multiple functions such as salt tolerance, growth promotion, nitrogen fixation, phosphorus solubilization, potassium solubilization, iron carrier production, indoleacetic acid production, prevention and control of grape powdery mildew and soil improvement. It is a multifunctional plant endophytic fungus, which is of great significance for promoting the growth of plants, preventing diseases and improving soil in saline soil conditions.

[0009] (2) The strain of the present invention is derived from young Cabernet Sauvignon grapes, is not pathogenic to humans and animals, and is safe to use.

[0010] In a second aspect, the present invention provides a microbial agent containing the aforementioned Bacillus zanthoxyli RX10.

[0011] Preferably, in the bacterial agent, Bacillus zanthoxyli RX10 exists in the form of cultured live bacteria, bacterial suspension, or fermentation broth.

[0012] Furthermore, the bacterial suspension is prepared by the following method:

[0013] Bacillus zanthoxyli RX10 was inoculated into LB liquid medium and cultured in a constant temperature shaking incubator at 37℃ and 180rpm for 24h. After centrifugation, the bacterial cells were collected and resuspended in sterile distilled water to prepare a bacterial suspension.

[0014] In a third aspect, the present invention provides the use of the above-mentioned Bacillus zanthoxyli RX10 or its inoculum in at least one of the following (1)-(3):

[0015] (1) Improve the photosynthetic capacity of plants under salt stress;

[0016] (2) Promote plant growth under salt stress conditions;

[0017] (3) Improve soil enzyme activity under salt stress conditions.

[0018] In the above applications, preferably, the plant is grape or corn.

[0019] In the above applications, the soil enzyme is one or more of sucrase, urease, FDA hydrolase, alkaline phosphatase, and neutral protease.

[0020] In a fourth aspect, the present invention provides the application of the above-mentioned Bacillus zanthoxyli RX10 or its inoculum in the following (1) or (2):

[0021] (1) Control of grape powdery mildew;

[0022] (2) Prepare agents for the prevention and control of grape powdery mildew.

[0023] The beneficial effects of this invention are:

[0024] (1) The Bacillus zanthoxyli RX10 of the present invention has excellent salt tolerance and can fix nitrogen, dissolve phosphorus, solubilize potassium, produce iron carrier and produce indoleacetic acid.

[0025] (2) The Bacillus zanthoxyli RX10 of the present invention can improve the photosynthesis of plants under salt stress and promote plant growth.

[0026] (3) The Bacillus zanthoxyli RX10 of the present invention can improve the activity of sucrase, urease, FDA hydrolase, alkaline phosphatase and neutral protease in soil under salt stress, and has the effect of improving soil.

[0027] (4) The Bacillus zanthoxyli RX10 of the present invention can also effectively prevent and control grape powdery mildew. In particular, under salt and alkali stress conditions, it can aggravate the disease caused by grape powdery mildew, while the Bacillus zanthoxyli RX10 of the present invention can still play a role in preventing and controlling grape powdery mildew under salt stress conditions.

[0028] (5) The Bacillus zanthoxyli RX10 of the present invention is a plant endophytic bacterium derived from young Cabernet Sauvignon grapes. It will not cause any harm to plants, can coexist well with various crops, is not pathogenic to humans and animals, and is highly safe to use. Attached Figure Description

[0029] Figure 1 This is a colony diagram of the RX10 strain of the present invention on LB solid medium.

[0030] Figure 2 This is a Gram staining image of the RX10 strain of the present invention.

[0031] Figure 3 The phylogenetic tree to be constructed.

[0032] Figure 4 This is a colony diagram of Bacillus zanthoxylum RX10 cultured on a combined nitrogen-fixing medium for 1 day.

[0033] Figure 5 This is a colony diagram of Bacillus zanthoxylum bungeanum RX10 cultured on silicate medium for 1 day.

[0034] Figure 6 Images of *Bacillus zanthoxylum bungeanum* RX10 colonies cultured on inorganic phosphorus medium for 4 days.

[0035] Figure 7 Images of *Bacillus zanthoxylum bungeanum* RX10 colonies cultured on CAS detection medium for 4 days.

[0036] Figure 8 The color development of Bacillus zinica RX10 under the Salksowski colorimetric method.

[0037] Figure 9 The results of quantitative determination of IAA production by Bacillus zanthoxylum bungeanum RX10.

[0038] Figure 10 The figure shows the growth characteristics of grape seedlings in pot experiments in Experiment Example 1.

[0039] Figure 11 The image shows the photosynthetic capacity results of the potted grape seedlings in Experiment Example 1.

[0040] Figure 12 The figure shows the results of the reactive oxygen species scavenging system measurement in the potted grape seedling experiment of Experiment Example 1.

[0041] Figure 13 The image shows the soil enzyme determination results of the potted grape seedling experiment in Experiment Example 1.

[0042] Figure 14 The image shows the results of the pot experiment on corn seedlings in Experiment Example 2.

[0043] Figure 15 This is a diagram illustrating the antagonistic effect of Experiment Example 3 on grape powdery mildew. Detailed implementation method:

[0044] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0045] To enable those skilled in the art to more clearly understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments. If specific experimental conditions are not specified in the embodiments, they are generally based on conventional conditions or conditions recommended by the reagent company; the reagents, consumables, etc. used in the following embodiments, unless otherwise specified, can be obtained commercially. Wherein:

[0046] M9 glucose medium: Dissolve 1g ammonium chloride, 0.13g magnesium sulfate, 3g potassium dihydrogen phosphate, 6g disodium hydrogen phosphate, and 0.338g glucose in 1L distilled water and sterilize at 115℃ for 20min.

[0047] Example 1: Isolation and purification of strains

[0048] The surface of young Cabernet Sauvignon grapes from the experimental field (116.16'N, 36.17'E) of the Horticultural Experiment Station of Shandong Agricultural University was washed with running water to remove surface adhering substances. One g of grape sample was weighed, disinfected with 75% alcohol for 30 seconds, washed 3-5 times with sterile distilled water, rinsed in 0.1% mercuric chloride solution for 1 minute, and then washed 5 times with sterile distilled water. The disinfected and cleaned young Cabernet Sauvignon grapes were placed in a high-temperature sterilized mortar, and an appropriate amount of sterilized quartz sand and 9 mL of sterile water were added. The plant sample was ground, and after grinding, it was allowed to stand for 30 minutes. Then, 100 μL of the supernatant was spread on M9 glucose medium and incubated at 28℃.

[0049] Single colonies with different morphological characteristics were selected for purification. The salt tolerance of the purified strains was determined using LB medium containing different concentrations of NaCl. The strain with the best salt tolerance (which could still grow on LB medium with 10% NaCl) was selected and named RX10, and stored in glycerol tubes.

[0050] Example 2: Identification of the strain

[0051] 1. Morphological and physiological-biochemical identification of the strain:

[0052] The colonies of strain RX10 on LB agar plates were round, milky white, opaque, with a rough, raised surface, sticky texture, and no halo. Figure 1 ).

[0053] Gram staining of stable strain RX10 yielded a purple color (…). Figure 2 This confirms that it is a Gram-positive bacterium. Under an optical microscope, it appears as a rod-shaped bacterium. The growth temperature of strain RX10 is 23–37℃, the pH range is 4–9, the optimal growth temperature is 37℃, and the optimal pH is 7.

[0054] 2. Identification of the strain's 16S rDNA:

[0055] Single colonies were picked from plates using the three-region streak method and activated on LB medium. The bacterial culture was then sent to Shanghai Sangon Biotech for sequencing. After sequencing, the sequencing assembly results were submitted to NCBI (https: / / www.ncbi.nlm.nih.gov / ) for BLAST sequence alignment. 16S rRNA sequences of strains from species closely related to the sequenced strains were obtained from GenBank. Six to eight sequences with over 98% homology were selected, and a phylogenetic tree was constructed using neighbor-joining with MEGA64 software. Phylogenetic analysis revealed that this strain had the highest sequence similarity to *Bacillus zanthoxyli*. Figure 3 ).

[0056] Based on the morphological, physiological and biochemical identification and 16S rDNA identification results, strain RX10 was identified as Bacillus zanthoxyli, and was biodeposited using a patented procedure. The biodeposit information is as follows:

[0057] Reference biological material (strain): RX10;

[0058] Suggested classification and nomenclature: Bacillus zanthoxyli;

[0059] Accession number: CCTCC M 20242733.

[0060] Example 3: Investigation on the growth-promoting performance of Bacillus zanthoxylum bungeanum RX10

[0061] 1. Test method:

[0062] The purified RX10 single colonies were inoculated into LB liquid medium and cultured at 37°C and 180 rpm for 24-48 hours for activation, followed by determination of their growth-promoting ability. The main growth-promoting indicators measured included: nitrogen fixation ability, potassium solubilization ability, phosphorus solubilization ability, siderophore production ability, and IAA production ability.

[0063] Methods for determining the nitrogen fixation capacity, potassium solubilization capacity, phosphorus solubilization capacity, and siderophore production capacity of the strain: The RX10 strain was activated on LB solid medium, and a single colony was picked and inoculated into the purchased medium for observation.

[0064] Nitrogen fixation capacity assay (combined nitrogen-fixing bacteria culture medium, catalog number HB8541), potassium solubilization capacity assay (silicate bacteria culture medium, catalog number HB8548-1), phosphorus solubilization capacity assay (inorganic phosphorus bacteria culture medium, catalog number HB8549-2), and siderophore production capacity assay (CAS detection culture medium, catalog number HB9132) were all purchased from Qingdao Haibo Biotechnology Co., Ltd.

[0065] Methods for determining IAA production capacity:

[0066] (1) Qualitative determination:

[0067] The isolated and purified RX10 strain was inoculated into a solution containing 200 mg / L of L-tryptophan. -1 The culture was incubated in LB liquid medium at 28°C and 180 rpm with shaking. After 4 days, the bacterial culture was removed and thoroughly mixed with Salksowski colorimetric solution at a ratio of 1:2. A positive control was also prepared using 50 mg / L of the solution. -1 Add IAA to Salksowski colorimetric solution. Observe after developing the color for 30 minutes at room temperature in the dark. If a pink color appears, it indicates that IAA has been produced.

[0068] (2) Quantitative determination:

[0069] The yield of IAA was determined by ultraviolet spectrophotometry. First, an IAA standard curve was plotted: 2 mL of IAA standard solution of various concentrations was added to test tubes, and the tubes were labeled. Then, 8 mL of Lalksowski colorimetric solution was added, and the mixture was incubated in the dark for 30 minutes. The OD was then measured using a spectrophotometer. 530 Then, plot the concentration of the IAA standard solution on the x-axis and the OD value on the y-axis. 530 Use the vertical axis to plot the standard curve.

[0070] Then, samples were taken every 12 hours, and the bacterial culture was centrifuged at 10,000 rpm for 10 minutes. The supernatant was then added to the same volume of Salkowski colorimetric solution, and the mixture was placed in the dark for 30 minutes for color development. The absorbance at a wavelength of 530 nm was then measured.

[0071] 2. Test Results:

[0072] The nitrogen fixation capacity test results of strain RX10 are as follows: Figure 4 As shown, the strain RX10 of this invention grows well on combined nitrogen-fixing medium (commercially available medium) and exhibits good nitrogen-fixing effect. The results of the strain's potassium-solubilizing ability test are as follows: Figure 5 As shown, strain RX10 was inoculated onto silicate medium (commercially available medium), and the colony morphology was transparent oil droplets, indicating that strain RX10 of this invention has a good potassium-solubilizing effect. The results of the phosphorus-solubilizing ability test of strain RX10 are as follows... Figure 6 As shown, the strain described in this invention can grow on inorganic phosphorus-solubilizing medium, and the colonies are surrounded by obvious phosphorus-solubilizing zones, indicating good phosphorus-solubilizing effects. The results of the siderophore production capacity test of strain RX10 are as follows... Figure 7 As shown, strain RX10 can grow on CAS detection medium, and the colonies have obvious orange-yellow rings around them, indicating that it has the ability to produce siderophores.

[0073] This invention also uses the Salksowski colorimetric method to qualitatively determine the IAA production capacity of strain RX10, using LB liquid medium containing 200 mg / L L-tryptophan without inoculation as a blank control and IAA as a positive control. The results are as follows: Figure 8 As shown, the solution was pink, indicating that the strain had the ability to produce IAA. A quantitative determination of IAA production capacity was then performed; after 72 hours, the amount of IAA secreted by strain RX10 was approximately 57.67 mg / L. Figure 9 ).

[0074] Example 4: Preparation of Bacillus zanthoxylum RX10 bacterial suspension

[0075] The purified strain RX10 was inoculated into LB liquid medium at a rate of 1% (v / v) and cultured at 37°C and 180 rpm for 24 h in a constant temperature shaking incubator. The fermentation broth was then transferred to sterile centrifuge tubes and centrifuged at 10,000 rpm for 10 min at room temperature. The supernatant was carefully discarded, and the cells were resuspended three times in sterile distilled water. The OD values ​​were then measured. 600 The absorbance value at 600 nm was adjusted to 1 to prepare a suspension of Bacillus zineb RX10.

[0076] Experiment 1: Growth-promoting experiment on Cabernet Sauvignon grape seedlings

[0077] 1. Test method:

[0078] Vermiculite and vineyard soil were mixed in a 1:1 mass ratio and sterilized to obtain mixed soil. One-year-old Cabernet Sauvignon seedlings were planted in the mixed soil. When the seedlings grew to 5-6 functional leaves, Cabernet Sauvignon seedlings of uniform size and growth were selected for further treatment.

[0079] The experiment consisted of four treatment groups:

[0080] Single-strain treatment (RX10): Water each seedling pot with 500mL of clean water once every 5 days; 3 days after watering, apply 50ml of the Bacillus pilosa RX10 bacterial suspension prepared in Example 4 to each pot once a week for a total of two applications of bacterial suspension.

[0081] Single salt stress treatment (NaCl): Water each seedling with 500mL of 250mM NaCl solution once every 5 days; 3 days after watering with NaCl solution, add 50ml of water to each pot once a week, for a total of two waterings.

[0082] Salt stress + bacterial treatment (NaCl + RX10): 500 mL of 250 mM NaCl solution was applied to each pot of seedlings every 5 days; 3 days after applying the NaCl solution, 50 mL of the Bacillus xibacillus RX10 bacterial suspension prepared in Example 4 was applied to each pot once a week for a total of two applications.

[0083] Control treatment (CK): Water each seedling with 500mL of clean water once every 5 days; 3 days after watering, add 50ml of clean water to each pot once a week, for a total of two waterings.

[0084] Water each seedling with 50mL of clean water once a week, for a total of two times.

[0085] Each treatment group consisted of 14 biological replicates and was treated for 28 days.

[0086] Sampling and measurement of various indicators, including: plant height, stem diameter, root length, aboveground fresh weight, root fresh weight, aboveground dry weight, root dry weight, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, water use efficiency, chlorophyll a content, chlorophyll b content, total chlorophyll content, carotenoid content, MDA content, hydrogen peroxide content, superoxide anion content, ascorbate peroxidase activity, peroxidase activity, superoxide dismutase activity, and reduced glutathione content.

[0087] In addition, the activities of sucrase, urease, catalase, FDA hydrolase, alkaline phosphatase, neutral protease, soil organic carbon content, soil organic matter content, soil available potassium content, soil available phosphorus content, soil alkaline nitrogen content, soil total potassium content, and soil total phosphorus content were measured in the treated soil.

[0088] The methods for determining the above indicators are all existing technical methods, or can be performed using existing instruments or reagent kits; for example, photosynthetic indicators were determined using the portable photosynthesis system TARGAS-1; hydrogen peroxide content (product number: G0168F), superoxide anion content (product number: G0129F), ascorbate peroxidase activity (product number: G0203F), peroxidase activity (product number: G0107F), superoxide dismutase activity (product number: G0103F), reduced glutathione content (product number: G0206F), sucrase activity (product number: G0302F), urease activity (product number: G0301F), and so on. Catalase activity (catalog number: G0303F), FDA hydrolase activity (catalog number: G0322F), alkaline phosphatase (catalog number: G0305F), and neutral protease activity (catalog number: G0315F) can be detected using the corresponding kits purchased from Suzhou Grace Biotechnology Co., Ltd.; soil organic matter content (potassium dichromate titration method-dilution heat method), soil available potassium content (flame photometry), soil available phosphorus content (molybdenum-antimony-colorimetric method), soil alkaline nitrogen content (alkaline diffusion method), soil total potassium content (flame photometry), and soil total phosphorus content (molybdenum-antimony-colorimetric method); the specific determination methods will not be described in detail here.

[0089] 2. Test Results:

[0090] like Figure 10 As shown, Cabernet Sauvignon seedlings inoculated with a suspension of *Bacillus zanthoxyli* under salt stress exhibited significantly higher biomass (fresh weight, dry weight, plant height, stem diameter, and root length) compared to uninoculated seedlings. Simultaneously, this strain significantly enhanced the photosynthetic efficiency of Cabernet Sauvignon seedlings. Figure 11 ) and reactive oxygen species scavenging system ( Figure 12 Furthermore, the inoculation of the strains under salt stress significantly improved the soil environment. Figure 13 ).

[0091] Experiment Example 2: Growth Promotion Experiment on Maize Seedlings

[0092] 1. Test method:

[0093] Vermiculite and cornfield soil were mixed in a 1:1 mass ratio and then sterilized to obtain mixed soil. Corn seedlings were planted in the mixed soil, and when the seedlings grew to two leaves and a bud, corn seedlings of uniform size and growth were selected for further treatment.

[0094] The experiment consisted of four treatment groups:

[0095] Single-strain treatment (RX10): At the beginning, thoroughly water the soil with clean water. After 3 days, water each seedling with 20 mL of the Bacillus xibacillus RX10 bacterial suspension prepared in Example 4. Water once a week for a total of three times.

[0096] Single salt stress treatment (NaCl): At the beginning, thoroughly water the soil with the same amount of NaCl solution (250mM) as the single inoculation treatment. After 3 days, water each seedling with 20mL of clean water once a week for a total of three times.

[0097] Salt stress + bacterial treatment (NaCl + RX10): At the beginning, the soil was thoroughly watered with the same amount of NaCl solution (250mM) as the single bacterial treatment. After 3 days, each seedling was watered with 20mL of the Bacillus xibacillus RX10 bacterial suspension prepared in Example 4, once a week for a total of three times.

[0098] Control treatment (CK): At the beginning, the soil was thoroughly watered with the same amount of water as the single-inoculation treatment. After 3 days, each seedling was watered with 20mL of water once a week for a total of three times.

[0099] Eight biological replicates were set up for each treatment group. Samples were taken on day 27 after treatment to measure various indicators, including: plant height, stem diameter, aboveground fresh weight, underground fresh weight, root length, dry weight, chlorophyll a content, chlorophyll b content, total chlorophyll content, and carotenoid content.

[0100] 2. Test Results:

[0101] like Figure 14 As shown, maize seedlings inoculated with Bacillus zanthoxyli suspension under salt stress conditions exhibited significantly higher biomass (total fresh weight, aboveground fresh weight, underground fresh weight, dry weight, plant height, and root length) compared to uninoculated maize seedlings. Furthermore, the inoculation of the strain significantly increased the content of photosynthetic pigments in maize seedlings under salt stress conditions.

[0102] Experiment Example 3: Antagonistic Experiment against Grape Powdery Mildew

[0103] 1. Test method:

[0104] Vermiculite and vineyard soil were mixed in a 1:1 mass ratio and sterilized to obtain mixed soil. One-year-old Cabernet Sauvignon seedlings were planted in the mixed soil. When the seedlings grew to 5-6 functional leaves, Cabernet Sauvignon seedlings of uniform size and growth were selected for further treatment.

[0105] Preparation of powdery mildew pathogen spore suspension: The pathogen causing grape powdery mildew is *Hylocereus undatus*. Infected grape leaves were collected, and powdery mildew spores were gently brushed into sterilized water. After mixing, a spore suspension was obtained. The spore concentration in the suspension was adjusted to ≥3 × 10⁻⁶ using a hemocytometer method. 6 / mL, ready for use.

[0106] The experiment consisted of four treatment groups:

[0107] Pathogen + fungicide treatment (powdery mildew + RX10): Water each seedling pot with 500mL of clean water, spray 20mL of powdery mildew pathogen spore suspension on both sides of the grape leaves, and after 3 days, apply 50ml of the Bacillus xib. RX10 fungal suspension prepared in Example 4 to each pot.

[0108] Salt stress + pathogen treatment (NaCl + powdery mildew): Apply 500mL of 250mM NaCl solution to each seedling pot, spray 20mL of powdery mildew pathogen spore suspension on both sides of the grape leaves, and after 3 days, apply 50ml of water to each pot.

[0109] Salt stress + pathogen + fungal treatment (NaCl + powdery mildew + RX10): Apply 500 mL of 250 mM NaCl solution to each seedling pot, spray 20 mL of powdery mildew pathogen spore suspension on both sides of grape leaves, and after 3 days, apply 50 mL of Bacillus pilosa RX10 fungal suspension prepared in Example 4 to each pot.

[0110] Control treatment (CK + pathogen): Water each seedling with 500mL of clean water, spray 20mL of powdery mildew pathogen spore suspension on both sides of the grape leaves, and 3 days later, apply 50mL of clean water to each seedling.

[0111] Fourteen biological replicates were set up for each treatment group to observe the growth of plants in each treatment and their resistance to powdery mildew.

[0112] 2. Test Results:

[0113] The results are as follows Figure 15 As shown, Cabernet Sauvignon seedlings inoculated with Bacillus zinniae RX10 suspension under pathogen stress showed significantly increased plant height compared to uninoculated seedlings, indicating a reduction in powdery mildew stress. Furthermore, under salt stress, the damage caused by powdery mildew pathogens to Cabernet Sauvignon seedlings increased. However, even under the dual stress of salt stress and pathogen stress, inoculation with Bacillus zinniae RX10 suspension still significantly reduced powdery mildew stress, and plant height also increased significantly. These results indicate that Bacillus zinniae RX10 can improve plant resistance to powdery mildew under salt stress conditions.

[0114] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A strain of Bacillus zanthoxylum ( Bacillus zanthoxyli RX10, with accession number CCTCC M20242733, is characterized by: The bacillus sp. (bacillus sp. Bacillus zanthoxyli ) RX10 is derived from young fruit of cabernet sauvignon grape, is a plant endophyte, has a round colony morphology on LB solid plate, has a milk-white and opaque body, has a rough and convex surface, is sticky, and has no halo; is gram-positive, has a growth temperature of 23-37℃, has a pH range of 4-9, and has a tolerance to NaCl concentration of 10%; and the bacillus sp. (bacillus sp. Bacillus zanthoxyli ) RX10 has at least one of the following functions: (1) simultaneously having the abilities of nitrogen fixation, potassium dissolution, phosphorus dissolution, iron carrier production and IAA production; (2) improving the activities of sucrose, urease, catalase, FDA hydrolytic enzyme, alkaline phosphatase, neutral protease, soil organic carbon content, soil organic matter content, soil available potassium content, soil available phosphorus content, soil alkali-hydrolyzed nitrogen content, soil total potassium content and soil total phosphorus content in salt stress soil; (3) improving the resistance of grape to grape powdery mildew under salt stress.

2. An inoculant characterized in that, The bacterial agent contains the bacillus fengkaii of claim 1 Bacillus zanthoxyli ) RX10.

3. The bacterial agent of claim 2, wherein The bacterial agent is Bacillus amyloliquefaciens (Bacillus amyloliquefaciens) Bacillus zanthoxyli ) RX10 exists in the form of cultivated live bacteria, bacterial suspension or fermentation broth.

4. The bacterial agent of claim 3, characterized in that, The bacterial suspension is prepared by the following method: Bacillus thiazolidinedilum ( Bacillus zanthoxyli RX10 was inoculated into LB liquid medium and cultured in a constant temperature shaking incubator at 37℃ and 180rpm for 24 h. After centrifugation, the bacterial cells were collected and resuspended in sterile distilled water to prepare a bacterial suspension.

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