Bacillus velezensis XF-8 and application thereof in prevention and treatment of tomato bacterial wilt

Abstract

The invention discloses bacillus velezensis XF-8 and application of the bacillus velezensis XF-8 in prevention and treatment of tomato bacterial wilt caused by Ralstonia solanacearum, and belongs to the technical field of microorganisms. The bacillus velezensis XF-8 capable of antagonizing Ralstonia solanacearum is obtained through separation and screening, and it is found that the bacillus velezensis XF-8 also has an excellent inhibition effect on various pathogenic fungi and shows broad-spectrum antibacterial activity of the bacillus velezensis XF-8. The bacillus velezensis XF-8 has a good inhibition effect on tomato bacterial wilt, and the control effect of the bacillus velezensis XF-8 in potted tomatoes reaches 74.25%. Results of the invention show that the bacillus velezensis XF-8 has a great application prospect in prevention and treatment of tomato bacterial wilt, and a good biocontrol resource is provided for research and development of a biocontrol agent for tomato bacterial wilt.

Description

Technical Field

[0001] The present invention discloses a strain of Bacillus velezensis XF-8 and its application in controlling tomato bacterial wilt caused by Ralstonia solanacearum, belonging to the field of microbial technology. Background Art

[0002] During the growth process of tomatoes, they are extremely vulnerable to various biotic and abiotic stresses, resulting in a significant decline in annual yield and quality. Tomato bacterial wilt is one of the serious soil-borne diseases, which is caused by Ralstonia solanacearum. The pathogen invades from the wounds of the roots or the base of the stem, spreads in the vascular tissue of the plant, causing blockage of the ducts and cell poisoning, resulting in the death of the stems and leaves due to the lack of normal water supply. The disease develops rapidly and is difficult to control. In severe cases, it even leads to a complete crop failure, seriously affecting the tomato yield. In addition, Ralstonia solanacearum can survive in the soil for many years and form latent infections in other plants, posing a threat to the development of the tomato planting industry in China.

[0003] At present, the control of tomato bacterial wilt mainly relies on the application of chemical fungicides, but the chemical control effect is not obvious, and the extensive use of chemical pesticides will cause pollution of the soil and water resources, ultimately seriously endangering human health. At the same time, the long-term use of the same chemical pesticide will cause drug resistance of the pathogenic bacteria. Using microorganisms or their metabolites to inhibit the occurrence of plant diseases, whose raw materials and active ingredients are natural products, conforms to the concept of sustainable development and is a green and environmentally friendly control method. Therefore, developing more biological control methods is of great significance for the control of tomato bacterial wilt.

[0004] Bacillus velezensis has become a hot spot in biological control applications in recent years due to its stable performance, strong stress resistance, and fast growth rate. However, its control effect is affected by environmental factors such as soil, and the effect is relatively unstable. Therefore, further exploring more high-quality strain resources is of great significance for agricultural production. Summary of the Invention

[0005] The purpose of the present invention is to provide a strain of Bacillus velezensis XF-8 and its application in controlling tomato bacterial wilt.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for screening and isolating antagonistic bacteria against tomato bacterial wilt, comprising the following steps:

[0008] 1) Weigh 10 g of soil sample into a sterilized conical flask, make up the volume to 100 mL with sterilized NB culture solution, shake culture at 30 °C and 200 r / min for 30 min; place it in a 75 °C water bath for 15 min to eliminate most harmful pathogens.

[0009] 2) Leave it to stand at room temperature until the soil particles sink to the bottom of the conical flask, take the supernatant for gradient dilution, and dilute the 10 -2 , 10 -3 , 10 -4 , 10 -5 , 10 -6 dilution solution and spread it on the NA medium.

[0010] 3) Activate the Ralstonia solanacearum and transfer it to the NB medium for culturing for 24 h, dilute it with sterile water in gradient, and the dilution factor is 10 -3 , and aspirate 200 μL and add it to the NA medium obtained after the treatment in step 2), and spread it evenly.

[0011] 4) After the inhibition zone is formed on the medium in step 3), streak and purify the mixed bacteria in the inhibition zone on a new NA medium, and then purify the single colony again until the colony size, morphology, and color in each bacterial culture dish are completely consistent.

[0012] 5) Heat and dissolve the NA medium, and when it cools to about 50 °C, add 200 μL of the Ralstonia solanacearum bacterial solution to every 100 mL of the medium, shake well, and then pour it into the bacterial culture dish.

[0013] 6) After culturing the bacteria purified in step 4) in the NB medium for 24 h, centrifuge the bacterial solution at 3500 r / min for 5 min, discard the supernatant, and then use the NB culture solution to make up the volume to 1 / 10 of the original volume, and mix well to obtain a 10-fold concentrated bacterial solution.

[0014] 7) Place a 6-mm round filter paper in the center of the solidified medium, aspirate 10 μL of the concentrated bacterial solution obtained in step 6) into the filter paper, and observe the presence or absence of the inhibition zone in each plate after culturing at 30 °C for 72 h to screen out the antagonistic bacteria against tomato bacterial wilt.

[0015] The present invention also provides a strain of Bacillus velezensis XF-8, including the following steps:

[0016] 1) Collect soil from the forest land of Guling in Fuzhou, Fujian, and screen out the strains that can antagonize Ralstonia solanacearum from it.

[0017] 2) After culturing the strain obtained in step 1) in the NA medium, the colony of the strain is light yellow, irregular in shape, serrated at the edge, opaque, with a small amount of wrinkles and slight bulges on the surface, dry, dull, and sticky; Gram staining is positive.

[0018] 3) Observe the strain obtained in step 1) under a scanning electron microscope, and the bacterial cells are short rod-shaped with blunt ends at both ends.

[0019] 4) The strain obtained in step 1) was subjected to physiological and biochemical tests, and it was found that the strain could produce acid by using mannose, fructose, and glucose, but could not produce acid by using lactose, raffinose, maltose, and sorbitol. The V-P test, catalase test, and nitrate reduction reaction were positive, while the MR test, oxidase test, and arginine dihydrolase test were negative. It could not utilize citrate, could hydrolyze gelatin, and could grow and survive in an environment with a salt concentration of 2%-10%.

[0020] 5) The DNA of the strain obtained in step 1) was extracted, and the PCR product was amplified using specific primers for 16S rRNA and gyrA, sequenced, and a phylogenetic tree was constructed. The strain obtained in step 1) was identified as Bacillus velezensis and named Bacillus velezensis XF-8.

[0021] The present invention also provides the application of the Bacillus velezensis XF-8 in the field of preventing and controlling tomato bacterial wilt, including the following applications:

[0022] 1) In a specific embodiment of the present invention, the Bacillus velezensis XF-8 has an antagonistic effect against Ralstonia solanacearum, the pathogen causing tomato bacterial wilt.

[0023] 2) In a specific embodiment of the present invention, the Bacillus velezensis XF-8 has a preventive and control effect on tomato bacterial wilt in detached tomato leaves.

[0024] 3) In a specific embodiment of the present invention, the Bacillus velezensis XF-8 has a significant preventive and control effect on tomato bacterial wilt in potted tomato plants.

[0025] Advantages and beneficial effects of the present invention:

[0026] 1. The present invention provides a direct screening method for strains capable of antagonizing pathogens, which can quickly and efficiently screen out beneficial strains, facilitating the further expansion of the strain resource library of biocontrol bacteria.

[0027] 2. The present invention provides a Bacillus velezensis XF-8 capable of antagonizing Ralstonia solanacearum, providing biocontrol resources for the prevention and control of plant diseases caused by Ralstonia solanacearum. Moreover, it is found that this strain also has good antibacterial activity against a variety of plant pathogenic fungi, demonstrating the broad antibacterial spectrum of Bacillus velezensis XF-8.

[0028] 3. The present invention provides a method for preventing and controlling tomato bacterial wilt in potted plants using Bacillus velezensis XF-8. The preventive and control effect in the greenhouse reaches 74.25%, which is higher than the 45.11% preventive and control effect of the pesticide control group. Moreover, the biocontrol agent used in this method avoids the environmental pollution and drug resistance caused by the use of chemical pesticides, is beneficial to the green production of tomatoes, and has great potential for developing into a commercial biocontrol agent for tomato bacterial wilt. Brief Description of the Drawings

[0029] Figure 1 In (A), it is the inhibition zone in the NA medium during the primary screening of the strain in Example 1 of the present invention; (B) is the plate colony morphology diagram of Bacillus velezensis XF-8 in the present invention; (C) is the inhibition zone diagram in the NA medium during the secondary screening of the strain in Example 1 of the present invention; (D) is the blank control for antibacterial (pathogen plate).

[0030] Figure 2 In (A), it is the optical microscope picture of Bacillus velezensis XF-8 in the present invention; (B) is the scanning electron microscope picture of Bacillus velezensis XF-8.

[0031] Figure 3 It is the gel electrophoresis diagram of the DNA sequence, 16S rRNA and gyrA gene sequence of Bacillus velezensis XF-8 in the present invention.

[0032] Figure 4 It is the phylogenetic tree diagram of Bacillus velezensis XF-8 constructed based on the 16S rRNA gene in the present invention.

[0033] Figure 5 It is the phylogenetic tree diagram of Bacillus velezensis XF-8 constructed based on the gyrA gene in the present invention.

[0034] Figure 6 It is the prevention and control effect diagram of Bacillus velezensis XF-8 on bacterial wilt of tomato detached leaves in the present invention.

[0035] Figure 7 It is the prevention and control effect diagram and prevention and control effect analysis diagram of Bacillus velezensis XF-8 on bacterial wilt of potted tomatoes in the present invention.

[0036] Figure 8 It is the inhibition effect diagram of Bacillus velezensis XF-8 on the growth of 10 kinds of pathogenic bacteria in the present invention.

[0037] Figure 9 It is the inhibition effect analysis diagram of Bacillus velezensis XF-8 on the growth of 10 kinds of pathogenic bacteria in the present invention. Detailed Embodiments

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings in the description of the specific embodiments or the prior art. Any product obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features that is the same as or similar to the present invention falls within the protection scope of the present invention.

[0039] The cultures used in the following examples: NB medium (g / L): beef extract 3 g, yeast extract 1 g, peptone 5 g, glucose 10 g, pH 7.0; NA medium (g / L): beef extract 3 g, yeast extract 1 g, peptone 5 g, glucose 10 g, agar 20 g, pH 7.0; PDA medium (g / L): 200 g of peeled potatoes, boiled for 25 min, filtered through eight layers of gauze to obtain the filtrate, added with 20 g of glucose and 20 g of agar.

[0040] Test soil samples: Forest soil samples were collected from Guling, Fuzhou City, Fujian Province (26°5′38″N, 119°23′51″E). The obtained soil samples were stored in a sealed bag and stored at -4°C for later use.

[0041] Test pathogens: The Ralstonia solanacearum, Colletotrichum nicotianae, Mycosphaerella arachidicola, Botrytis cinerea, Fusarium solani, Fusarium oxysporum, Magnaporthe grisea, Pythium aphanidermatum, Cryptophthora africanum, Valsa mali, and Fusarium avenaeum used in this experiment were all preserved by the State Key Laboratory of Ecological Control of Crop Pests in Fujian and Taiwan.

[0042] Test tomato leaves: The tomato leaves used in this experiment were collected from the greenhouse of the State Key Laboratory of Ecological Control of Crop Pests in Fujian and Taiwan. The sizes of the collected leaves were similar. The tomato plants had grown for 60 days and were of the Hong'ai sheng tomato variety.

[0043] Test tomato plant seeds: The seeds of the Hong'ai sheng tomato plants used in this experiment were provided by the State Key Laboratory of Ecological Control of Crop Pests in Fujian and Taiwan.

[0044] Example 1: Screening, isolation, and purification of antagonistic bacteria against tomato bacterial wilt

[0045] 1) Weigh 10 g of soil sample into a sterilized conical flask, make up the volume to 100 mL with sterilized NB culture solution, shake culture at 30°C and 200 r / min for 30 min; place it in a 75°C water bath for 15 min to eliminate most harmful pathogens.

[0046] 2) Let it stand at room temperature until the soil particles sink to the bottom of the conical flask. Take the supernatant for gradient dilution, and dilute it to 10 -2 , 10 -3 , 10 -4 , 10 -5 , 10 -6 . Then spread the diluted solution on the NA medium.

[0047] 3) Activate the Ralstonia solanacearum and transfer it to the NB medium for culturing for 24 h. Gradient dilute it with sterile water to a dilution of 10 -3 . Then pipette 200 μL of it onto the NA medium obtained in step 2) and spread it evenly.

[0048] 4) After the inhibition zone ( Figure 1 A in ) is formed on the medium in step 3), streak the mixed bacteria in the inhibition zone on a new NA medium for purification. Then purify the single colonies again until the colony size, morphology, and color in each bacterial culture dish are completely consistent.

[0049] 5) Heat and dissolve the NA medium. When it cools to about 50 °C, add 200 μL of the Ralstonia solanacearum bacterial solution to every 100 mL of the medium, shake well, and then pour it into the bacterial culture dish.

[0050] 6) After culturing the bacteria purified in step 4) in the NB medium for 24 h, centrifuge the bacterial solution at a speed of 3500 r / min for 5 min, discard the supernatant, and then make up the volume to 1 / 10 of the original volume with the NB culture solution and mix well to obtain a 10-fold concentrated bacterial solution.

[0051] 7) Place a 6-mm round filter paper in the center of the solidified medium. Pipette 10 μL of the concentrated bacterial solution obtained in step 6) onto the filter paper. After culturing at 30 °C for 72 h, observe the presence or absence of the inhibition zone in each petri dish to screen out the antagonistic bacteria against tomato bacterial wilt. As Figure 1 shown in (C) in , the diameter of the inhibition zone in the NA medium added with the isolated strain reaches 4.15 cm. Number this strain as XF-8.

[0052] Example 2. Identification of Bacillus velezensis XF-8

[0053] 1. Morphological identification of Bacillus velezensis XF-8

[0054] Observation on the plate: Streak the strain XF-8 on the NA medium and culture it in an incubator at 30 °C for 48 h. Then observe the morphological characteristics of the bacterial colonies on the plate, such as the shape and size, edge, color and transparency, elevation, and surface gloss.

[0055] Optical microscope observation: The strain XF-8 was subjected to Gram staining, which was carried out successively according to the steps of smearing, drying, primary staining, mordanting, decolorizing, counterstaining, and microscopic examination. After completion, it was observed using an optical microscope.

[0056] SEM observation: The cells of the strain XF-8 were fixed in 2.5% glutaraldehyde solution at 4 °C overnight, and then observed by SEM (Hitachi, SU8020, Japan, 5.0 kV).

[0057] Figure 1 It can be seen from (B) that the colonies of the strain XF-8 are light yellow, irregular in shape, serrated at the edges, opaque, with a small amount of wrinkles on the surface, slightly raised, dry, dull, and sticky. Figure 2 It can be seen from (A) that the Gram staining is positive. Figure 2 It can be observed from the SEM image in (B) that the cells are short rod-shaped with blunt ends.

[0058] 2. Physiological and biochemical identification of Bacillus velezensis XF-8

[0059] The physiological and biochemical identification method was referred to the "Manual of Systematic Identification of Common Bacteria". After the antagonistic strain XF-8 was cultured on NA medium at 30 °C for 24 h, the utilization tests of nitrogen sources and carbon sources, MR test, V-P test, nitrate reduction test, catalase test, oxidase test, gelatin liquefaction test, arginine dihydrolase test, and salt tolerance and other physiological and biochemical characteristics were determined. The determination results were compared with the "Bergey's Manual of Determinative Bacteriology" and the "Manual of Systematic Identification of Common Bacteria" to analyze the physiological and biochemical characteristics of this antagonistic strain.

[0060] It can be seen from Table 1 that the strain XF-8 can utilize mannose, fructose, and glucose to produce acid, but cannot utilize lactose, raffinose, maltose, and sorbitol to produce acid. The V-P test, catalase test, and nitrate reduction reaction are positive, the MR test, oxidase test, and arginine dihydrolase test are negative, it cannot utilize citrate, can hydrolyze gelatin, and can grow and survive in an environment with a salt concentration of 2% - 10%.

[0061] Table 1 Physiological and biochemical results

[0062]

[0063] Note: "+" indicates a positive reaction; "-" indicates a negative reaction.

[0064] 3. Molecular biological identification of Bacillus velezensis XF-8

[0065] For the antagonistic strain XF-8 to be identified, pick a single colony of the strain activated on the plate and inoculate it into NB medium. Incubate it at 30 °C with shaking at 200 r / min for 24 h, and extract it using the Bacterial Genomic DNA Kit (Cat. No.: CAT#9763) from Baorui Biotechnology (Beijing) Co., Ltd. as the PCR template.

[0066] Use the 16S rRNA gene-specific primers (F: AGAGTTTGATCMTGGCTCAG; R: GGTTACCTTGTTACGACTT) and gyrA gene-specific primers (F: GCGTCACGGCGRATCCTCAA; R: AAATCTGCCCGTATCGTCG) synthesized by Sangon Biotech (Shanghai) Co., Ltd. The PCR amplification system (20 μL): ddH2O 6 μL, DNA template 2 μL, forward primer 1 μL, reverse primer 1 μL, 2×Hieff Canace Plus PCR Master Mix (With Dye) 10 μL. PCR amplification program: pre-denaturation at 98 °C for 3 min; denaturation at 98 °C for 10 s, extension at 68 °C for 45 s, number of cycles 35; final extension at 72 °C for 5 min. Finally, take 2 μL of the PCR product for agarose gel electrophoresis. The gel electrophoresis diagram ( Figure 3 ) shows that the 16S rRNA gene and gyrA gene fragments are approximately at 1500 bp and 800 bp respectively.

[0067] Sangon Biotech (Shanghai) Co., Ltd. sequenced the PCR products of the 16S rRNA and gyrA genes. The obtained sequences were compared through the BLAST program in the NCBI database to obtain the strain sequences with a relatively high degree of similarity; the Neighbor-joining method in MEGA11 software was used to construct the phylogenetic tree. According to the comparison results of the 16S rRNA gene sequence of strain XF-8 and the constructed phylogenetic tree ( Figure 4 ) It can be seen that: the similarity between strain XF-8 and Bacillus reaches 100%, and the confidence level that strain XF-8 and Bacillus velezensis 3726 (MT538583.1) cluster in the same branch is as high as 91%; according to the comparison results of the gyrA gene sequence of strain XF-8 and the constructed phylogenetic tree ( Figure 5 ) It can be seen that: the similarity between strain XF-8 and Bacillus reaches 98%, and the confidence level that strain XF-8 and Bacillus velezensis Hx05 (CP029473.2) cluster in the same branch is as high as 99%.

[0068] Based on the morphological identification, physiological and biochemical identification, and molecular biological identification results of the comprehensive strain XF-8, the strain XF-8 was identified as Bacillus velezensis, so it was named Bacillus velezensis XF-8.

[0069] Example 3: Determination of the control effect of Bacillus velezensis XF-8 on detached tomato leaves

[0070] Pour the bacterial solution of Bacillus velezensis XF-8 with a concentration of 1×10 8 CFU / mL, the bacterial solution of Ralstonia solanacearum with a concentration of 1×10 8 CFU / mL, and kasugamycin with a concentration of 50 mg / L into different sterile bacterial culture dishes respectively for standby.

[0071] Pick 15 tomato leaves of the same size, first disinfect them with 1% NaClO, and rinse them thoroughly with sterile water, repeating 3 times; then disinfect them with 75% alcohol, and rinse them thoroughly with sterile water, repeating 3 times; use a sterile syringe to make a small hole on both sides of each tomato leaf for standby.

[0072] Each leaf after the above treatment was placed in a sterile culture dish containing a bacterial solution of Ralstonia solanacearum with a concentration of 1×10 8 CFU / mL and soaked for 30 s and then taken out; then placed in a sterile culture dish containing a bacterial solution of Bacillus velezensis XF-8 with a concentration of 1×10 8 CFU / mL and soaked for 30 s. Soaking in clear water for 30 s was used as the blank control, and soaking in a sterile culture dish containing kasugamycin with a concentration of 50 mg / L for 30 s was used as the chemical control. Each treatment was repeated 5 times; the treated tomato leaves were placed in a sterile culture dish with filter paper, the absorbent cotton ball was kneaded into a ball and fixed at the petiole, and wetted with an equal amount of sterile water.

[0073] Figure 6 It can be seen that the control group had severe disease, and the tomato leaves showed wilting and large-area yellowing; in the kasugamycin treatment group, the tomato leaves had small-area yellowing and the disease of the leaves was relatively mild, indicating that kasugamycin had a certain control effect on tomato bacterial wilt caused by Ralstonia solanacearum infection; the tomato leaves in the Bacillus velezensis XF-8 treatment group basically maintained the normal color. This experiment shows that Bacillus velezensis XF-8 has a good biological control effect on tomato bacterial wilt of detached leaves.

[0074] Example 4: Determination of the control effect of Bacillus velezensis XF-8 on potted tomato bacterial wilt

[0075] The red dwarf tomato seeds were soaked for 2 h for germination acceleration and then sown in a seedling tray filled with sterilized nutrient soil. They were watered regularly with a small amount of clear water every day. When the tomato seedlings had two leaves and one heart, the seedlings with good growth were transplanted into 10-cm flower pots filled with sterile nutrient soil and vermiculite in a ratio of 2:1. After culturing for 2 months at a temperature of 26 °C with a daily light duration of 16 h, tomato plants with the same growth were selected for the determination of control efficacy.

[0076] The bacterial suspension of Ralstonia solanacearum with a concentration of 1×10 8 CFU / mL was diluted 100 times and then evenly sprayed on each tomato plant. After 12 h, the bacterial suspension of Bacillus velezensis XF-8 with a concentration of 1×10 8 CFU / mL was also diluted 100 times and evenly sprayed on the tomato plants. Spraying clear water was used as the blank control, and spraying kasugamycin with a concentration of 50 mg / L was used as the chemical control. After culturing for 2 weeks, the disease index and control efficacy were investigated. Each treatment included four tomato plants, and the experiment was repeated 3 times. Disease index = (number of diseased tomato plants × disease grade) / (total number of test tomato plants × highest disease grade) × 100; Control efficacy (%) = [(disease index of blank control - disease index of treatment group) / disease index of blank control] × 100%. Grading standard for tomato bacterial wilt: Healthy plants were at grade 0; 1 - 2 branches showed wilting symptoms at grade 1; 3 - 5 branches showed wilting symptoms at grade 2; 1 - 2 leaves were dry, chlorotic, and yellow at grade 3; All leaves were wilted, the stem was dry and chlorotic, and the stem of the plant could not be straightened normally at grade 4.

[0077] Figure 7 It can be seen that in the control group (A) where only the bacterial suspension of Ralstonia solanacearum was sprayed, a large number of adventitious roots were produced at the stem of the tomato plants, a large number of leaves withered and turned yellow, and in severe cases, the stem of the plant could not be straightened normally. In the tomato plants treated with kasugamycin spraying (B), a large number of adventitious roots were also produced at the stem, and some leaves withered and turned yellow, but the plants could still be straightened. In the tomato plants treated with the bacterial suspension of Bacillus velezensis XF-8 spraying (C), only a small number of adventitious roots and a small number of leaves wilted and drooped appeared in some plants. The control efficacy of the strain XF-8 treatment group against tomato bacterial wilt was as high as 74.25%, which was significantly higher than that of the control pesticide group kasugamycin (45.11%).

[0078] Example 5. Determination of the broad-spectrum antibacterial property of Bacillus velezensis XF-8

[0079] The inhibition effect of Bacillus velezensis XF-8 on 10 pathogenic bacteria was determined by the plate confrontation method. The specific steps were as follows: Each pathogenic bacterium was inoculated in the center of the PDA medium with a 6-mm puncher. 6-mm filter paper was placed at two quarter points of the diameter of the medium. 10 μL of the Bacillus velezensis XF-8 bacterial solution cultured for 24 h was taken and placed on the filter paper; the control group was not inoculated with Bacillus velezensis XF-8. After culturing at 30 °C for 4 d, the colony diameter was measured and the inhibition rate was calculated. Each treatment group was repeated 3 times. Inhibition rate (%) = (colony diameter of the control group - colony diameter of the treatment group) / (colony diameter of the control group - diameter of the bacterial cake) × 100%.

[0080] Figure 8 The plate confrontation method was used to determine that Bacillus velezensis XF-8 had an inhibitory effect on 10 pathogenic fungi. And Figure 9 The results showed that the antifungal rates of Bacillus velezensis XF-8 against 10 pathogenic fungi were as follows: A. Fusarium solani f. sp. melongenae 41.19%, B. Mycosphaerella arachidicola 55.92%, C. Botrytis cinerea 48.27%, D. Colletotrichum tabacum 56.89%, E. Fusarium oxysporum f. sp. cubense 52.35%, F. Magnaporthe oryzae 46.86%, G. Pythium aphanidermatum 49.84%, H. Cryptophlebia leucotreta 54.56%, I. Valsa mali 42.76%, J. Fusarium avenaceum 48.77%.

[0081] The above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. 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 the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A Bacillus velezensis as an antagonist bacterium against Ralstonia solanacearum and various plant pathogenic fungi, characterized in that, The Bacillus velezensis is named Bacillus velezensis XF-8 and has been deposited in the Key Laboratory of Biopesticide and Chemical Biology of the Ministry of Education, Fujian Agriculture and Forestry University. The deposit date is January 22, 2024. The pathogenic fungi include Fusarium solani, Mycosphaerella arachidicola, Botrytis cinerea, Colletotrichum nicotianae, Fusarium oxysporum, Magnaporthe grisea, Pythium aphanidermatum, Cryptophthora africanum, Valsa mali, Fusarium avenaeum.

2. Application of the Bacillus velezensis XF-8 described in claim 1 in the field of preventing and controlling bacterial wilt of solanaceous plants.

3. The application according to claim 2, wherein The prevention and control includes the prevention and control of tomato bacterial wilt.

4. A biological control preparation for tomato bacterial wilt, characterized in that, The preparation includes the Bacillus velezensis XF-8 described in claim 1 or its fermentation broth.

5. A method for preventing and treating tomato bacterial wilt caused by Ralstonia solanacearum, characterized in that, It includes the following steps: S1: Control the viable cell concentration of Bacillus velezensis XF-8 described in claim 1 to 1×10 8 CFU / mL; S2: Dilute the bacterial liquid obtained in S1 by 100 times and evenly spray it on tomato plants.

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