Bacillus siamensis and application thereof

Abstract

The invention discloses a bacillus siamensis strain and application thereof. Belongs to the technical field of agricultural microorganisms. When the bacillus siamensis QTJ2-5 provided by the invention is used for preventing and treating pathogenic fungi of leaf diseases, the bacillus siamensis QTJ2-5 has a relatively wide antibacterial spectrum, has a good prevention and treatment effect on leaf diseases caused by northern leaf blight of helminthosporium terrestris, helminthosporium maydis and curvularia lunata, can reduce the attack degree of the leaf diseases of the corn, and has a good prevention and treatment effect and a good prevention and treatment effect on leaf diseases caused by the helminthosporium terrestris and the curvularia lunata. Environmental pollution cannot be caused, and sustainable development is facilitated. Therefore, the discovery of the bacillus siamensis QTJ2-5 has great significance in preventing and treating plant fungal diseases.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural microorganisms, and more particularly to a siam bacillus and application thereof. Background Art

[0002] Plant fungal diseases are diseases caused by plant pathogenic fungi, accounting for about 70-80% of plant diseases. Several or even dozens of fungal diseases can be found on a crop. Common symptoms include downy mildew, white powder, white rust, black powder, rust powder, sooty mildew, black moles, mold, mushrooms, cotton wool, granules, ropes, clay particles and small black spots. The symptoms of fungal diseases are closely related to the classification of pathogenic fungi, and fungal diseases have a serious impact on the development of agricultural production.

[0003] In corn production, corn leaves are often infected by plant pathogenic fungi, showing symptoms of leaf diseases such as corn leaf spot, corn round spot, and corn Curvularia leaf spot. The pathogens of the above leaf diseases are mainly as follows: Helicoverpa ulmoides, Helicoverpa lunulata, and Curvularia lunulata. The occurrence and prevalence of the disease are affected by many factors such as the disease resistance of the inbred lines, crop rotation system, climatic conditions, and cultivation measures. With the promotion of disease-resistant hybrids and changes in cultivation systems, plant fungal diseases were once controlled, but further research and prevention are needed.

[0004] At present, due to the prominent spread of air and water flow of fungal diseases, chemical agents are generally used for protective control, or by improving cultivation and management measures. Although chemical control is simple to operate and has significant effects, it has the disadvantage of damaging the environment; the improvement of cultivation and management techniques has little effect on the improvement of the incidence rate. Plant rhizosphere bacteria are bacteria that mainly grow in the rhizosphere soil of plants. They interact with plants and promote the improvement of plant disease resistance. Bacillus and Pseudomonas are the earliest research objects of plant rhizosphere bacteria. Bacillus can produce spores in harsh natural environments so that it can survive to this day, so it has been widely studied. Siamese Bacillus can be found in the rhizosphere soil of most plants. It inhibits some fungal soil-borne diseases by producing protein antibacterial substances, lipopeptide antibacterial peptides, volatile organic compounds, etc. However, the currently known Siamese Bacillus still has some disadvantages, such as: most of the prevention and control effects are poor, and the objects of action are relatively single. These problems will greatly reduce the control effect of this strain on plant diseases.

[0005] Therefore, how to provide a siam bacillus and a microbial agent thereof that can effectively prevent and control plant fungal diseases and has a broad antibacterial spectrum is a problem that those skilled in the art urgently need to solve. Summary of the invention

[0006] In view of this, the present invention provides a siam bacillus and application thereof.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A strain of Bacillus siamensis, the Bacillus siamensis is named QTJ2-5, and its classification name is Bacillus siamensis. It was deposited in the General Microbiology Center of China Microorganism Culture Collection Administration on September 24, 2024, with a deposit number of CGMCC No.32051, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0009] The invention discloses an application of a strain of Bacillus siamensis in preventing and controlling fungal diseases of plant leaves. The Bacillus siamensis is named QTJ2-5, and its classification name is Bacillus siamensis. It was deposited in the General Microbiological Center of China National Microbiological Culture Collection Committee on September 24, 2024, with a deposit number of CGMCC No.32051, and the deposit address is No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing.

[0010] Furthermore, the plant is corn.

[0011] Furthermore, the fungal diseases on plant leaves are Helminthosporium maxima, Helminthosporium zeae, and Curvularia lunata.

[0012] A medicament for preventing and treating plant fungal diseases, comprising the above-mentioned Bacillus siamensis.

[0013] Further, it also includes a dispersant, a UV protective agent and a film-forming agent;

[0014] The dispersant is CMC-Na;

[0015] The ultraviolet protection agent is sorbitol;

[0016] The film-forming agent includes chitosan and a glutaraldehyde cross-linking agent.

[0017] A method for preventing and controlling plant fungal diseases, using the above-mentioned Bacillus siamese.

[0018] It can be seen from the above technical solution that, compared with the prior art, the beneficial effects achieved by the present invention are:

[0019] The present invention screens and purifies a Siamese Bacillus QTJ2-5 with a broad antibacterial spectrum, which can effectively prevent and control plant fungal diseases, especially has good control effects on Helicoverpa serrata, Helicoverpa zeae, and Curvularia lunata. The present invention provides a Siamese Bacillus and a microbial agent thereof that can achieve good control effects on plant fungal diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0021] Figure 1 This is a diagram showing the antibacterial effect of strain QTJ2-5 on plant pathogenic fungi in Example 2 of the present invention;

[0022] Figure 2 This is a statistical diagram of the antibacterial effect of strain QTJ2-5 on plant pathogenic fungi in Example 2 of the present invention;

[0023] Figure 3 This is a cluster analysis diagram of 16S rDNA of strain QTJ2-5 in Example 3 of the present invention;

[0024] Figure 4 This is a schematic diagram of the colony morphology of Bacillus siamese QTJ2-5 in Example 5 of the present invention;

[0025] Figure 5 The experimental results of optimizing different carbon sources for the fermentation medium in Example 6 of the present invention;

[0026] Figure 6 The experimental results of optimizing different nitrogen sources for the fermentation medium in Example 6 of the present invention;

[0027] Figure 7 The experimental results of optimizing different inorganic salt sources of the fermentation medium in Example 6 of the present invention;

[0028] Figure 8 The experimental results of optimizing the different pH values ​​of the fermentation medium in Example 6 of the present invention;

[0029] Fig. 9 The results of the experiments with different liquid loading amounts in Example 6 of the present invention are shown below:

[0030] Fig.10 The results of the experiments for optimizing different inoculum amounts in Example 6 of the present invention are as follows;

[0031] Fig.11 The results of the experiments for optimizing different culture temperatures in Example 6 of the present invention are as follows;

[0032] Fig.12 The results of the experiments for optimizing different rotation speeds in Example 6 of the present invention are as follows;

[0033] Fig.13 The results of the experiments for optimizing different culture times in Example 6 of the present invention are as follows;

[0034] Fig.14 The invention relates to the preparation of the biocontrol agent of Bacillus siamese QTJ2-5 in Example 7 of the present invention;

[0035] Fig.15 This is a diagram showing the disease resistance effect of the siam bacillus QTJ2-5 biocontrol agent on indoor corn leaves in Example 8 of the present invention;

[0036] Fig.16 This is a statistical diagram of the disease resistance effect of the siam bacillus QTJ2-5 biocontrol agent on indoor corn leaves in Example 8 of the present invention;

[0037] Fig.17 This is a diagram showing the disease resistance effect of the siam bacillus QTJ2-5 biocontrol agent on field corn leaves in Example 9 of the present invention;

[0038] Fig.18 This is a statistical diagram of the disease resistance data of the siam bacillus QTJ2-5 biocontrol agent on field corn leaves in Example 9 of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The drugs required for the present invention are conventional experimental drugs, purchased from commercial channels;

[0041] The experimental methods not mentioned are conventional experimental methods and will not be described in detail here.

[0042] Example 1

[0043] Isolation of strains

[0044] In this experiment, 1 g of soil from the roots of corn plants with severe leaf diseases was placed in a test tube, and 9 mL of sterile water was added, mixed and diluted thoroughly. 100 μL of 10 -4 , 10 -5 , 10 -6 The solutions with different dilution multiples were smeared on the LB solid culture plate. After the liquid was dried on the plate, the culture plate was placed in a 37°C incubator for dark culture for 24 h. The single Bacillus colonies grown on the LB solid culture plate were observed and picked out, and cultured in a 96-well plate filled with liquid LB (one single colony was cultured in each well). The plates were shaken and cultured at 37°C and 220 r / min for 12 h, and the bacteria were preserved in glycerol and stored in an ultra-low temperature refrigerator.

[0045] Example 2

[0046] Screening of antagonistic strains

[0047] (1) Activation culture of Exserohilum turcicum: Heat the sterile PDA medium and pour it into a plate until the plate is evenly covered. Allow it to cool and solidify before use. Pick the hyphae of Exserohilum turcicum (Pass.) Leonard et Suggs in the center of a fresh PDA solid plate and culture it in the dark at 27°C for 7 days until the plate is full of hyphae.

[0048] (2) Preliminary screening: Take 1 μL of the bacterial solution stored in the 96-well plate in Example 1 and inoculate it into a second 96-well plate (100 μL of liquid LB in each well). The strain numbers of the two 96-well plates should correspond to each other, and culture them at 37°C and 150 r / min for 12 h. Using the plate confrontation method, use the large spot disease helminth spore as the pathogen, use a 6 mm diameter puncher to punch holes in the plate full of pathogens, place the bacterial cake in the center of the prepared fungal culture dish, and spot 2 μL of bacterial solution at a distance of 3 cm from the bacterial cake. Use the 6-point method to spot, and place it upside down in a 27°C incubator. After 7 days, observe and record whether there is an obvious inhibition zone.

[0049] (3) Rescreening: Number and record the strains that show obvious antibacterial circle effects on the PDA culture dish of Helminthosporium spp., purify single colonies by streaking method, and pick single colonies to activate in liquid LB culture medium. Use the plate confrontation method and 4-point method to spot samples, repeat 3 times for each strain, place them upside down in a 27℃ incubator, and observe and record the size of the antibacterial circle after 7 days. Select the strain with the best antibacterial effect. Figure 1 , Figure 2 , named QTJ2-5.

[0050] (4) Leaf fungal disease inhibition test: Growth inhibition test was conducted on Bipolaris zeicola (Stout) Shoem. and Curvularia lunata (Wakker) Boedijn.

[0051] Pick a single colony of strain QTJ2-5 into a 50 mL Erlenmeyer flask filled with 20 mL LB liquid medium and culture overnight in a shaker at 220 r / min and 37 °C. Adjust the OD 600 = 1. Using the plate confrontation method, the plant pathogenic fungi with a diameter of 6 mm were cultured in confrontation with the fermentation liquid of QTJ2-5. Each treatment was repeated 3 times and cultured in a constant temperature incubator at 27°C for 7 days to observe the antibacterial effect. Figure 1 , Figure 2 shown.

[0052] Strain QTJ2-5 has a good inhibitory effect on the above plant pathogenic fungi, indicating that strain QTJ2-5 has a broad antibacterial spectrum.

[0053] Example 3

[0054] Sequencing and analysis of 16S rDNA of strain QTJ2-5

[0055] DNA of strain QTJ2-5 was extracted using a bacterial genomic DNA rapid extraction kit (DL111-01), and the 16S rDNA sequence was amplified using bacterial universal primers.

[0056] The primer sequences are: 27F (5'-AGAGTTTGATCCTGGCTCAG-3', SEQ ID NO. 1) and 1492R (5'-GGTTACCTTGTTACGACTT-3', SEQ ID NO. 2).

[0057] PCR reaction system: 25 μL 2×EcoTaqPCR SuperMix, 2 μL each of 0.4 μmol / L forward and reverse primers, 4 μL genomic DNA, 17 μL ddH2O, total volume 50 μL.

[0058] PCR reaction conditions: 94°C pre-denaturation for 2 min, 94°C denaturation for 30 s, annealing for 55 s, 72°C extension for 55 s, 72°C insulation for 2 min, and 30 cycles.

[0059] The PCR amplification product was spotted on a 1.0% agarose gel and electrophoresed at 140V for 20 minutes to recover the target band. The PCR product was sequenced by Bomed Gene Co., Ltd. The 16S rDNA sequence of the strain is as follows:

[0060]

[0061] The sequencing results were submitted to NCBI, and the Blast function option in the NCBI database was used to perform similarity comparison with known sequences. The maximum likelihood method in Mega 7.0 software was used to analyze the evolutionary relationship of the bacterial 16S rDNA gene, and the Bootstrap value was set to 1000. According to the comparison results, it can be inferred that strain QTJ2-5 is Bacillus siamese. The results are as follows Figure 3 shown.

[0062] Example 4

[0063] Deposit of strain QTJ2-5

[0064] Strain QTJ2-5, whose classification name is Bacillus siamensis, was deposited in the General Microbiology Center of China Microorganism Culture Collection Administration on September 24, 2024, with the deposit number CGMCC No.32051, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0065] Example 5

[0066] Physiological and biochemical test identification of strains

[0067] Preliminary physiological and biochemical identification of Siamese Bacillus QTJ2-5 was carried out, including Gram assay, catalase reaction, VP test, starch hydrolysis test, etc. The test methods used adopted the conventional test methods for measuring such physiological and biochemical indicators in the art. The results are shown in Table 1.

[0068] Table 1 Physiological and biochemical indexes of Bacillus siamese QTJ2-5

[0069]

[0070] Observe the colony morphology of Bacillus siameensis QTJ2-5, such as Figure 4 The cell morphology is rod-shaped, the colony is off-white, opaque, the surface is dry and wrinkled, and the edge is slightly wrinkled and yellowish.

[0071] Example 6

[0072] Culture medium and culture conditions screening test

[0073] Glucose, yeast extract powder and sodium chloride are used as the carbon source, nitrogen source and inorganic salt components of the basal culture medium respectively.

[0074] Glucose, lactose, soluble starch, sucrose, and maltose were used to replace the carbon source of the basal culture medium to verify the effect and screen out the optimal carbon source. The results are shown in Figure 5 When soluble starch is used as the carbon source, the bacteria grow fastest.

[0075] Ammonium sulfate, yeast extract powder, peptone, beef extract, and soybean cake powder were used to replace the nitrogen source of the basic culture medium to verify the effect, and the best nitrogen source was screened out. The results are shown in Figure 6 When yeast extract powder is used as nitrogen source, the bacteria grow fastest.

[0076] Calcium chloride, copper sulfate, magnesium sulfate, sodium chloride, and potassium nitrate were used to replace the inorganic salts in the basal culture medium to verify the effect, and the inorganic salt with the best effect was screened out. The results are shown in Figure 7 When calcium chloride is an inorganic salt, the bacteria grow fastest.

[0077] The pH of the basal culture medium was adjusted to 6, 7, 8, and 9 respectively to verify the effect, and the pH value with the best effect was screened out. The results are shown in Figure 8 When the pH value is 7, the bacteria grow fastest.

[0078] The effects were verified by using 75mL / 250mL, 100mL / 250mL, 125mL / 250mL, and 150mL / 250mL as the basal culture medium volumes, and the optimal volume was selected. The results are shown in the table. Fig. 9 When the liquid volume is 75mL / 250mL, the bacteria grow fastest.

[0079] The effect was verified by using 4%, 6%, 8% and 10% as the inoculum amount of the basal culture medium, and the best inoculum amount was selected. The results are shown in Fig.10 When the inoculation amount was 6%, the bacteria grew fastest.

[0080] The effect was verified by using 25℃, 28℃, 37℃ and 42℃ as the culture temperature, and the best culture temperature was selected. The results are shown in Fig.11 When the culture temperature is 28℃, the bacteria grow fastest.

[0081] The effect was verified by using 160r / min, 180r / min, 200r / min and 220r / min as the speed, and the speed with the best effect was selected. The results are shown in Fig.12 When the speed is 220r / min, the bacteria grows fastest.

[0082] The effect was verified by using 24h, 36h, 48h and 72h as the culture time, and the culture time with the best effect was selected. The results are shown in Fig.13 When the culture time is 24h, the bacteria grows fastest.

[0083] Example 7

[0084] Preparation of Siamese Bacillus QTJ2-5 Biocontrol Agent

[0085] Preparation method of Siamese Bacillus QTJ2-5 seed solution:

[0086] The siam bacillus QTJ2-5 is inoculated into a seed culture medium for culture. The seed culture medium preferably comprises: 8.0-12.0 g / L tryptone, 4.0-10.0 g / L sodium chloride, 5.0-10.0 g / L yeast extract, and a pH value of 6-9, and more preferably comprises 10.0 g / L tryptone, 10.0 g / L sodium chloride, 5.0 g / L yeast extract, and a pH value of 7.

[0087] The temperature of the seed liquid culture is preferably 25-42° C., more preferably 28° C., the time is preferably 12-24 h, more preferably 12 h, and the rotation speed is preferably 160-220 rpm, more preferably 220 rpm.

[0088] PEG 1000, CMC-Na and sodium polyphosphate were selected as dispersant alternative materials, respectively. They were added to the newly prepared solid LB culture medium at 1.5% (M / V), and then sterilized with high-pressure steam to make plates. The seed solution of Siamese Bacillus QTJ2-5 was diluted 5 times, and 0.1 mL was evenly spread on the plates containing different dispersants. The LB plates without dispersants were used as controls. The plates were cultured at 37°C for 1 day, and the number of live bacteria was calculated. The plate with the largest number of live bacteria was the optimal dispersant. The experiment was repeated 3 times. Fig.14 When the dispersant component is CMC-Na, the number of colonies is the largest, with an average of 173.

[0089] Glucose, sucrose and sorbitol were used as alternative materials for UV protectants, respectively. They were added to the newly prepared solid LB culture medium at 0.1% (M / V) to make different types of plates. The seed solution of Siamese Bacillus QTJ2-5 was diluted 5 times, and 0.1 mL was evenly spread on the plates containing different UV protectants. The LB plates without UV protectants were used as controls. After the plates were dried, they were placed at 20 cm from a 20W UV lamp for 30 minutes, and then cultured at 37°C for 1 day. The number of live bacteria was calculated, and the plate with the largest number of live bacteria was the one with the best UV protectant. The experiment was repeated 3 times. Fig.14 When the UV protectant ingredient was sorbitol, the number of colonies was the highest, with an average of 171.

[0090] Inoculate Siamese Bacillus QTJ2-5 in a seed culture medium and culture it at a speed of 220 rpm and a temperature of 28°C for 12 hours. Centrifuge the seed liquid at 8000 rpm for 10 minutes, remove the supernatant, and retain the bacterial mud precipitate. Stir the screened dispersant and ultraviolet protective agent with the bacterial mud precipitate obtained by centrifugation at a mass ratio of 3% and 1.5%, respectively, and then mix it evenly with a film-forming agent with a mass ratio of 10% (the film-forming agent includes chitosan and glutaraldehyde cross-linking agent, the chitosan mass concentration is 2%, and the glutaraldehyde cross-linking agent accounts for 1.5% of the chitosan mass) to obtain a biocontrol agent (coating agent). Finally, mix the seeds with Zhengdan 958 corn white seeds at a ratio of 1mL / 50 seeds, and obtain the coated seeds after drying in the shade. Fig.14 shown.

[0091] Example 8

[0092] Indoor test

[0093] This experiment was conducted in the greenhouse of the College of Life Sciences of Hebei Agricultural University at a temperature of 23°C and a humidity range of 30-48%. In the experiment, Zhengdan 958 corn white seeds with full grains and uniform size and the coated seeds prepared in Example 7 were selected for sowing as the control group and the test group, respectively. After the corn germinated, 50 ml of Siamese Bacillus QTJ2-5 bacterial solution (prepared the culture medium with the most suitable composition, inoculated seed solution, pH 7, liquid volume 75 ml / 250 ml, inoculation amount 6%, 220 rpm, 28°C, fermentation 24h) was applied to the roots of the corn in the test group, and fresh culture medium was applied to the control group.

[0094] When the corn plants grow to the 7-leaf stage, the 4th and 5th leaves of the corn plants are selected for pathogen inoculation. Use a sterile needle to gently scratch a 2-4 mm wound on the corn leaves, and use a pipette to draw 200 μL of diluted Tween20 and drop it on the cut. Place 6 mm bacterial plates of three pathogenic fungi, namely, the large spot disease convex umbilical worm spore, the corn life umbilical worm spore, and the crescent spore mold on the leaf wound, wrap it with plastic wrap for moisturizing, and grow in the dark in the artificial intelligence culture room for 24 hours, and grow normally for 3-7 days. Observe the disease status of the inoculated part of the corn leaves every day. When the leaf lesions are obvious, take pictures of the lesions and count the lesion area.

[0095] The indoor efficacy of biocontrol agents was analyzed. The results showed that after inoculation with three pathogenic fungi, corn leaves in both the test group and the control group had different degrees of disease, and the control group was more serious, with the corn leaves at the bacterial disk shrunken and turned light brown, and the area gradually expanded to the surrounding area. The disease in the test group was significantly less than that in the control group, and only along the bacterial disk position did it turn light brown, such as Fig.15 . Five days after inoculation, the lesion area of ​​corn leaves in the test group was smaller than that in the blank control group, and the inhibitory effect was statistically calculated, such as Fig.16Through analysis, it was found that the biocontrol agent can effectively inhibit the infection of Helminthosporium convexum of large spot disease, Helminthosporium convexum of corn, and Curvularia lunata.

[0096] Example 9

[0097] Field trials

[0098] The field test was conducted in the experimental field of Hebei Agricultural University. In the test, Zhengdan 958 corn white seeds with full grains and uniform size were selected as the control for sowing. The same mass of white seeds were selected to prepare coated seeds (the preparation method is the same as in Example 7) and sowed as the QTJ2-5 test group. After the corn 3-leaf seedling stage, 100ml of Siamese Bacillus QTJ2-5 bacterial liquid supplement was applied to the roots of the corn in the QTJ2-5 test group (prepare the culture medium with the most suitable composition, inoculate the seed liquid, pH 7, liquid volume 75ml / 250ml, inoculation amount 6%, 220rpm, 28°C, fermentation 24h), and the control group was applied with fresh culture medium.

[0099] When the corn plants grow to the 8-leaf stage, the 4th and 5th leaves of the corn plants are selected for pathogen inoculation. Use a sterile needle to gently scratch the corn leaves with a 2-4 mm wound, and use a pipette to draw 200 μL of diluted Tween20 and drop it on the cut. Place 6 mm fungus discs of three pathogenic fungi, such as the large spot disease convex umbilical worm spore, corn life umbilical worm spore, and crescent spore on the wound of the leaves, wrap them with plastic wrap for moisturizing, and grow normally for 5-10 days. Observe the disease status of the inoculated part of the corn leaves every day. When the leaf lesions are obvious, take pictures of the lesions, calculate the area of ​​​​the disease, and conduct statistical analysis of the incidence.

[0100] According to the proportion of diseased plants in the total number, the resistance level of the test corn to corn leaf diseases is divided into 5 levels, as shown in Table 2.

[0101] Table 2 Disease classification standards

[0102]

[0103] Disease index = [∑(number of diseased leaves at each level × relative disease level) / (number of leaves under investigation × 9)] × 100%;

[0104] Control effect (%) = [(CK-Pt) / CK] × 100%;

[0105] CK represents the disease index of the control group, and Pt represents the disease index of the experimental group.

[0106] Table 3 Effect of seed dressing on the prevention of corn leaf diseases

[0107]

[0108] The overall analysis of the field efficacy of biocontrol agents showed that after the pathogenic fungus disc was inoculated, the corn leaves of the test group and the control group were affected to varying degrees, and the control group was more serious, with the corn leaves at the bacterial disc shrunken and turning light brown, and the area gradually expanding to the surrounding area. The disease in the test group was significantly less than that in the control group, and only along the bacterial disc did it turn light brown, such as Fig.17 . Seven days after inoculation, the lesion area of ​​corn leaves in the test group was smaller than that in the control group, and the inhibitory effect was statistically calculated, such as Fig.18 Through analysis, it was found that biocontrol agents can effectively inhibit the infection of plant pathogens.

[0109] The control group and QTJ2-5 test group of the field test were investigated and data were collected. The results showed that the incidence of corn leaf diseases was significantly reduced after corn seeds were coated with Siamese Bacillus QTJ2-5 and the bacterial solution was applied. The control effect of the bacterial agent treatment reached more than 40%, and the incidence was reduced by 18.27% compared with CK. This shows that in the field test, Siamese Bacillus QTJ2-5 can effectively prevent and control the occurrence of corn leaf diseases such as the convex umbilical spore, the corn flat umbilical spore, and the crescent spore, and effectively inhibit the occurrence of corn leaf diseases.

[0110] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0111] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A siam bacillus, characterized in that: The Siamese Bacillus is named QTJ2-5, and its classification name is Bacillus siamensis. It was deposited in the General Microbiology Center of China Microorganism Culture Collection Administration on September 24, 2024, with the deposit number CGMCC No.32051, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

2. The use of a strain of Bacillus siamensis in preventing and controlling fungal diseases of plant leaves, wherein the Bacillus siamensis is named QTJ2-5, and its classification name is Bacillus siamensis. It was deposited in the General Microbiological Center of China Microbiological Culture Collection Committee on September 24, 2024, with a deposit number of CGMCC No.32051, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

3. The use according to claim 2, characterized in that The plant is corn.

4. The use according to claim 2, characterized in that The fungal diseases of plant leaves are Helminthosporium maxima, Helminthosporium zeae, and Curvularia lunata.

5. A medicament for preventing and treating plant fungal diseases, characterized in that: The invention comprises the siam bacillus as described in claim 1.

6. The agent according to claim 5, characterized in that Also includes dispersants, UV protectants and film formers; The dispersant is CMC-Na; The ultraviolet protection agent is sorbitol; The film-forming agent includes chitosan and a glutaraldehyde cross-linking agent.

7. A method for preventing and controlling plant fungal diseases, characterized in that: The siam bacillus according to claim 1 is used.

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