Paenibacillus polymyxa strain and application thereof in prevention and treatment of plant diseases

Abstract

The application belongs to the technical field of agricultural microorganisms, and particularly relates to a plant endophytic Paenibacillus polymyxa and application thereof in preventing and treating plant diseases. Paenibacillus polymyxa The plant endophytic Paenibacillus polymyxa has the strain number PP8, the classification name Paenibacillus polymyxa, the preservation number CGMCC No. 36638, and is preserved in the China General Microbiological Culture Collection Center on November 17, 2025. The Paenibacillus polymyxa has broad-spectrum inhibitory activity on pathogenic fungi, oomycetes and bacteria, and can produce significant inhibitory effect on plant pathogenic microorganisms through multiple action mechanisms. In addition, the Paenibacillus polymyxa PP8 has the ability to colonize in the internal tissue of plant roots, can exist in the plant body and play the disease-inhibiting effect, thereby further enhancing the prevention and control effect on soil-borne diseases and improving the persistence and stability of the biological control effect.

Description

Technical Field

[0001] This application belongs to the field of agricultural microbiology technology, and specifically relates to a plant endophytic polymyxa bacillus and its application in the prevention and control of plant diseases. Background Technology

[0002] Soil-borne diseases are a common and serious type of plant disease in agricultural production. They are mainly caused by pathogenic microorganisms such as fungi, bacteria, and oomycetes that survive in the soil for a long time and infect the crop roots or root collar. Common soil-borne diseases include wilt, root rot, damping-off, and seedling blight caused by pathogens such as Fusarium oxysporum, Rhizoctonia solani, Pythium, and Phytophthora. These diseases are characterized by their high degree of concealment, wide spread, and high recurrence rate. Once they occur, they are often difficult to eradicate completely, seriously affecting crop yield, quality, and the stability of the agricultural ecosystem.

[0003] Currently, control measures for soil-borne diseases mainly include chemical control, agricultural cultivation regulation, and biological control. While chemical pesticides can rapidly suppress disease occurrence to some extent, long-term or excessive use can easily lead to pesticide resistance in pathogens. They can also cause soil microecological imbalance, pesticide residues, and environmental pollution, making them unsuitable for the safety and sustainability requirements of modern agriculture. Therefore, developing efficient, safe, and environmentally friendly biological control technologies has become an important direction for development in this field.

[0004] Endophytic bacteria have attracted widespread attention due to their ability to colonize plants long-term and form stable symbiotic relationships with their host plants. Compared with microorganisms that only function in the soil or rhizosphere, endophytic bacteria can directly colonize the root, stem, or leaf tissues of plants, and are less affected by soil environmental fluctuations, rainfall erosion, and external competing microorganisms, thus exhibiting advantages such as long-lasting control effects and high stability. Endophytic biocontrol bacteria can not only directly inhibit the growth of pathogens by secreting antibacterial active substances, but also synergistically enhance the plant's resistance to soil-borne diseases by competing for nutrients and ecological niches within the plant and inducing systemic resistance. Therefore, they show great application potential in the integrated management of soil-borne diseases.

[0005] Polymyxin Bacillus ( Paenibacillus polymyxa Polymyxa (Bacillus polymyxa) is a class of beneficial microorganisms widely distributed in soil and plant roots, possessing advantages such as spore formation, strong environmental adaptability, and good stability. Current research indicates that Polymyxa can inhibit soil-borne pathogens through multiple pathways, including secreting antimicrobial active substances such as lipopeptides, competing for nutrients and ecological niches, inducing systemic resistance in plants, and promoting plant growth. It shows promising application prospects in the field of biological control of plant diseases.

[0006] However, due to differences in strain origin and genetic characteristics, different Bacillus polymyxa strains exhibit significant variations in colonization ability, antibacterial activity, antibacterial spectrum, metabolite types, and field control efficacy. Some strains reported in existing technologies still suffer from unstable control efficacy, limited inhibition of specific soil-borne pathogens, or insufficient environmental adaptability in practical applications, making it difficult to meet the demand for highly efficient and stable biocontrol agents in agricultural production.

[0007] Therefore, screening and obtaining a new strain of Bacillus polymyxa that possesses both strong endophytic colonization ability and significant soil-borne disease inhibition effect, can stably survive in plants and soil environment and play a biocontrol role, and is suitable for promotion and application in agricultural production is of great significance for improving the biological control effect of soil-borne diseases, reducing the use of chemical pesticides, and promoting the green and sustainable development of agriculture. Summary of the Invention

[0008] This application provides a plant endophytic polymyxa bacillus strain PP8 and its applications. Studies have shown that this strain can colonize within plants and exhibits broad-spectrum inhibitory activity against soil-borne pathogens in crops. Furthermore, its biocontrol and growth-promoting mechanisms have been clarified, providing a new and effective strain and theoretical basis for the green control of plant diseases such as soybean.

[0009] Firstly, this application provides a plant endophytic polymyxa bacillus strain, designated PP8 and classified as *Bacillus polymyxa*. Paenibacillus polymyxa The accession number is CGMCC No. 36638, and it was deposited at the China General Microbiological Culture Collection Center on November 17, 2025.

[0010] Secondly, this application also provides a microbial bactericide containing the *Bacillus polymyxa* and / or a culture of the *Bacillus polymyxa* described in the first aspect.

[0011] Furthermore, the culture is a substance obtained by culturing the polymyxa bacillus in a microbial culture medium.

[0012] In this application, "culture" refers to a general term for liquid or solid products (i.e., fermentation products) that have grown microbial communities after artificial inoculation and cultivation. It is a product obtained by growing and / or amplifying microorganisms, which can be a biologically pure culture of microorganisms or contain a certain amount of culture medium, metabolites, and / or other components produced during the cultivation process. "Culture" also includes passaged cultures obtained by subculturing microorganisms, which can be a culture of a single generation or a mixture of several generations.

[0013] In this application, the metabolites can be obtained from the fermentation broth of *Bacillus polymyxa*. The fermentation broth of *Bacillus polymyxa* can be sterile or contain bacteria. The sterile fermentation broth is obtained by fermenting *Bacillus polymyxa* in a liquid culture medium and then filtering the fermentation broth using a bacterial filter.

[0014] In this application, the microbial agent may further include a carrier. The carrier may be a solid carrier or a liquid carrier. The solid carrier may be a mineral material or a biological material; the mineral material may be at least one selected from peat moss, clay, talc, kaolin, montmorillonite, white carbon, zeolite, silica, and diatomaceous earth; the biological material may be at least one selected from various crop straws, pine shells, rice straw, peanut shells, corn flour, soybean flour, starch, peat moss, and animal manure; the liquid carrier may be water.

[0015] In this application, the microbial agent can be in various dosage forms, such as liquid, emulsion, suspension, powder, granules, wettable powder, or water-dispersible granules. Depending on the need, surfactants (such as Tween 20, Tween 80, etc.), binders, stabilizers (such as antioxidants), pH adjusters, etc., may also be added to the agent.

[0016] Thirdly, this application also provides the application of the plant endophytic polymyxa bacillus described in the first aspect or the microbial bactericide described in the second aspect, wherein the application is any one of the following:

[0017] A1) Promotes plant growth;

[0018] A2) Prepare products that promote plant production;

[0019] A3) Inhibit plant pathogens:

[0020] A4) Prepare products that inhibit plant pathogens;

[0021] A5) Nitrogen fixation, phosphorus dissolution, potassium decomposition, and / or iron carrier generation;

[0022] A6) Prepare products that produce nitrogen fixation, phosphorus solubilization, potassium solubilization and / or iron carrier production.

[0023] Furthermore, the plant pathogens include pathogenic fungi, pathogenic oomycetes, and pathogenic bacteria.

[0024] Furthermore, the pathogenic fungus is selected from Fusarium graminearum (Fusarium graminearum). Fusarium graminearum Fusarium oxysporum ( Fusarium oxysporum Rhizoctonia solani ( ), Rhizoctonia solani Rhizoctonia solani Fusarium pseudograss () Fusarium pseudograminearum) Botrytis cinerea ( Botrytis cinerea Verticillium dahliae Verticillium dahliae ), Flathead anthrax bacteria (Colletotrichum truncatum ), Sclerotinia sclerotiorum ( Sclerotinia sclerotiorum Fusarium solani () Fusarium solani One or more of the following.

[0025] Furthermore, the pathogenic oomycete is selected from *Pythium tertrum* (…). Pythium ultimum ), Phytophthora capsici ( Phytophthora capsici ), Phytophthora ( Phytophthora cactorum ), Phytophthora parasiticum ( Phytophthora parasitica ), soybean phytotoxicum ( Phytophthora sojae One or more of the following.

[0026] Furthermore, the pathogenic bacteria are selected from Ralstonia solanacearum (Ralstonia solanacearum). Ralstonia solanacearum ), rice bacterial leaf streak ( Xanthomonas oryzae pv. oryzicola ), rice bacterial blight pathogen ( Xanthomonas oryzae pv. oryzae Kiwi fruit canker pathogen ( Pseudomonas syringae pv. actinidae ), *Pseudomonas syringae* tomato pathogenic strain ( Pseudomonas syringae pv. tomato One or more of the following.

[0027] Fourthly, this application also provides a method for preventing and controlling plant diseases, the method comprising treating plants or plant culture media with the polymyxa bacillus described in the first aspect or the microbial fungicide described in the second aspect.

[0028] Furthermore, the plant disease is caused by at least one pathogen described in the third aspect.

[0029] Furthermore, the plant can be a monocotyledonous or dicotyledonous plant. The monocotyledonous plant can be wheat, rice, corn, sugarcane, etc., and the dicotyledonous plant can be soybean, potato, alfalfa, tobacco, tomato, cucumber, apple, etc. Preferably, the plant can be soybean, alfalfa, or pine.

[0030] Preservation Information

[0031] Classification and nomenclature: Polymyxin Bacillus Paenibacillus polymyxa

[0032] Latin name: Paenibacillus polymyxa

[0033] Accession number: CGMCC No. 36638

[0034] Deposit date: November 17, 2025

[0035] Preservation Institution: China General Microbiological Culture Collection Center (CGMCC)

[0036] Address of the depository: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0037] Compared with the prior art, this application has the following technical effects.

[0038] 1) The *Bacillus polymyxa* PP8 strain provided in this application exhibits broad-spectrum inhibitory activity against pathogenic fungi, oomycetes, and bacteria, and can significantly inhibit plant pathogenic microorganisms through multiple mechanisms of action. Both the bacterial cells and fermentation broth of this strain demonstrate good disease control effects, indicating diverse modes of action and stable efficacy, which is beneficial for improving the reliability of biological control applications. Furthermore, *Bacillus polymyxa* PP8 has the ability to colonize within plant root tissues, allowing it to persist within the plant and exert its disease-suppressing effect, thereby further enhancing its control effect against soil-borne diseases and improving the persistence and stability of biological control efficacy.

[0039] 2) Through pot experiments and field trials, *Bacillus polymyxa* PP8 demonstrated good control efficacy under various environmental conditions, indicating its strong environmental adaptability and suitability for widespread application in practical agricultural production. Using the strain described in this invention for disease control can effectively reduce the use of chemical pesticides, lower environmental pollution risks, and meet the requirements of green agriculture and sustainable development. Attached Figure Description

[0040] Figure 1 A phylogenetic tree for Bacillus polymyxa PP8 was constructed based on whole-genome sequencing results.

[0041] Figure 2 Morphological characteristics of Bacillus polymyxa PP8; including A. colony morphology and B. Gram staining.

[0042] Figure 3 The results are for the growth-promoting ability of Bacillus polymyxa PP8; among them, A. nitrogen fixation ability; B. potassium solubilization ability; C. siderophore production ability; D. phosphorus solubilization ability.

[0043] Figure 4 The image shows the inhibitory effect of *Bacillus polymyxa* PP8 on pathogenic fungi; from left to right in the image are *Fusarium graminearum* (…). Fusariumgraminearum Fusarium oxysporum ( Fusariumoxysporum Rhizoctonia solani ( ), Rhizoctonia solani Rhizoctoniasolani Fusarium pseudograss () Fusariumpseudograminearum) Botrytis cinerea ( Botrytiscinerea Verticillium dahliae Verticilliumdahliae ), Flathead anthrax bacteria (Colletotrichumtruncatum ), Sclerotinia sclerotiorum ( Sclerotiniasclerotiorum Fusarium solani () Fusarium solani ).

[0044] Figure 5 The figure shows the inhibitory effect of *Bacillus polymyxa* PP8 on pathogenic oomycetes; from left to right in the figure are *Pythium oxysporum* (…). Pythiumultimum ), Phytophthora capsici ( Phytophthoracapsici ), Phytophthora ( Phytophthoracactorum ), Phytophthora parasiticum ( Phytophthoraparasitica ), soybean phytotoxicum ( Phytophthorasojae ).

[0045] Figure 6 The image shows the inhibitory effect of *Bacillus polymyxa* PP8 on pathogenic bacteria; from left to right in the image are *Ralstonia solanacearum* (…). Ralstoniasolanacearum ), rice bacterial leaf streak ( Xanthomonas oryzae pv. oryzicola ), rice bacterial blight pathogen ( Xanthomonas oryzae pv. oryzae Kiwi fruit canker pathogen ( Pseudomonas syringae pv. actinidae ), *Pseudomonas syringae* tomato pathogenic strain ( Pseudomonas [[ID="59"]]syringae pv. tomato ).

[0046] Figure 7 The inhibitory effect of Bacillus polymyxa PP8 fermentation broth on pathogens (fungi, oomycetes).

[0047] Figure 8 The inhibitory effect of Bacillus polymyxa PP8 fermentation broth on pathogenic bacteria.

[0048] Figure 9 The effects of Bacillus polymyxa PP8 bacterial culture and fermentation broth on plant growth.

[0049] Figure 10 This shows the colonization status of Polymyxin Bacillus PP8 in plants.

[0050] Figure 11 The efficacy of Bacillus polymyxa PP8 in controlling diseases in potted plants after artificial inoculation of soybean seeds with the pathogen was evaluated.

[0051] Figure 12 The efficacy of Bacillus polymyxa PP in potted plants artificially inoculated with the pathogen was evaluated.

[0052] Figure 13 This study investigated the field efficacy of Bacillus polymyxa PP8 in soybean fields. Detailed Implementation

[0053] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions, conditions described in a laboratory manual, or conditions recommended by the manufacturer.

[0054] Example 1: Strain PP8 is a polymyxa bacillus.

[0055] Strain PP8 was isolated from soybean roots and phylogenetic analysis was performed using the Type (Strain) Genome Server (TYGS) platform. Based on whole-genome sequence alignment, the genomic distance between the tested strain and known type strains and closely related strains in the database was calculated. Combined with genomic similarity indicators such as digital DNA-DNA hybridization (dDDH), the phylogenetic relationships between strains were quantitatively analyzed. Based on this, a phylogenetic tree was constructed using a phylogenetic algorithm.

[0056] The results are as follows Figure 1 The results showed that strain PP8 clustered with the model strain of *Bacillus polymyxa* within the same phylogenetic clade, indicating a close phylogenetic relationship with *Bacillus polymyxa* at the genomic level, thus identifying it as *Bacillus polymyxa*. Paenibacillus polymyxa ).

[0057] Example 2 Morphological identification

[0058] Polymyxin Bacillus PP8 was inoculated onto LB solid medium and cultured at 37°C for 1 day. Its morphological characteristics were then observed. Results are as follows: Figure 2 The colonies were nearly round, viscous, milky white, with a moist and smooth surface and irregular edges; the Gram staining result was positive.

[0059] Example 3: Detection of the growth-promoting ability of Bacillus polymyxa PP8

[0060] like Figure 3 As shown in Figure A, after PP8 was inoculated onto Assumption nitrogen-fixing medium and cultured at 30°C for 3 days, the strain grew normally, indicating its nitrogen-fixing ability. In Figure B, after PP8 was inoculated onto potassium-solubilizing bacteria solid medium and cultured at 30°C for 3 days, a clear zone appeared around the strain, indicating its potassium-solubilizing ability. In Figure C, after PP8 was inoculated onto CAS detection medium and cultured at 30°C for 5 days, an orange-yellow halo appeared around the colony, indicating its ability to produce siderophores. In Figure D, after PP8 was inoculated onto Monkina medium and cultured at 30°C for 5 days, a clear zone appeared around the Monkina medium, indicating its ability to dissolve organophosphates.

[0061] Example 4: Bacillus polymyxa PP8 exhibits broad-spectrum resistance

[0062] The inhibitory activity of strain PP8 against pathogenic fungi, oomycetes, and bacteria was determined using the plate confrontation method. The selected pathogenic fungus was *Fusarium graminearum* (…). Fusarium graminearum Fusarium oxysporum ( Fusarium oxysporum Rhizoctonia solani ( ), Rhizoctonia solani Rhizoctonia solani Fusarium pseudograss () Fusarium pseudograminearum) Botrytis cinerea ( Botrytis cinerea Verticillium dahliae Verticillium dahliae ), Flathead anthrax bacteria ( Colletotrichum truncatum ), Sclerotinia sclerotiorum ( Sclerotinia sclerotiorum Fusarium solani () Fusarium solani ); Pathogenic oomycetes: Pythium cerevisiae ( Pythium ultimum ), Phytophthora capsici ( Phytophthora capsici ), Phytophthora ( Phytophthora cactorum ), Phytophthora parasiticum ( Phytophthora parasitica ), soybean phytotoxicum ( Phytophthora sojae ); Pathogenic bacteria: Ralstonia solanacearum ( Ralstonia solanacearum ), rice bacterial leaf streak ( Xanthomonas oryzae pv. oryzicola ), rice bacterial blight pathogen ( Xanthomonas oryzae pv. oryzae Kiwi fruit canker pathogen ( Pseudomonas syringae pv. actinidae ), *Pseudomonas syringae* tomato pathogenic strain ( Pseudomonas syringae pv. tomato ).

[0063] The method for detecting pathogenic fungi and oomycetes is as follows: Add 20 mL of PDA / V8 medium to each 90 mm diameter petri dish. Use a 6 mm diameter punch to create filter paper discs, stacking two layers together and attaching them around the perimeter of the plate. Add 20 μL LOD to each disc. 600 The control group was prepared with a 1.0 μL polymyxin Bacillus PP8 bacterial suspension. An equal volume of dd water was added to the control group, and a 6 mm diameter pathogen block was inoculated in the center of the plate.

[0064] The method for identifying pathogenic bacteria is as follows: Use 90 mm diameter petri dishes, adding 20 mL of LB medium to each dish. Take 200 μL of OD... 600 For a 1.0 μL bacterial suspension of pathogenic bacteria, a plate was prepared. Filter paper discs were punched out using a 6 mm diameter punch, stacked in a single layer, and then applied to a plate. 20 μL of OD was added to each disc. 600 The bacterial suspension of Bacillus polymyxa PP8 was 1.0.

[0065] The results are as follows Figure 4 , Figure 5 and Figure 6The results showed that Bacillus polymyxa PP8 had a good inhibitory effect on pathogenic fungi, oomycetes, and bacteria.

[0066] Example 5: Antibacterial activity of Bacillus polymyxa PP8 metabolites

[0067] The PP8 strain was inoculated into NB liquid medium at 30°C and shaken at 180 rpm for 72 hours. The resulting bacterial culture was centrifuged at 12000g for 15 min, and the supernatant was filtered through a 0.22μm bacterial filter to obtain sterile fermentation broth.

[0068] The fermentation broth was mixed with NB medium at ratios of 45% and 65%, and the mixture was poured onto plates. Soybean Phytophthora was then inoculated into the center of each plate. Phytophthora sojae ), Phytophthora parasiticum ( Phytophthora parasitica ), Phytophthora ( Phytophthora cactorum Fusarium oxysporum ( Fusarium oxysporum ).

[0069] Take 200 μL of OD respectively 600 Rice bacterial leaf streak pathogen 1.0 ( Xanthomonas oryzae pv. oryzicola ), rice bacterial blight pathogen ( Xanthomonas oryza e pv. oryzae Kiwi fruit canker pathogen ( Pseudomonas syringae pv. actinidae ), *Pseudomonas syringae* tomato pathogenic strain ( Pseudomonas syringae pv. tomato The bacterial culture was spread on a plate, and after attaching a layer of filter paper around the perimeter, 20 μL of sterile fermentation broth was added.

[0070] The results are as follows Figure 7 and Figure 8 The results showed that the sterile fermentation broth had a good inhibitory effect on pathogenic fungi, oomycetes, and bacteria.

[0071] Example 6: Effects of Bacillus polymyxa PP8 bacterial culture and fermentation broth on plant growth

[0072] Prepare bacterial suspension and sterile fermentation broth (prepared according to the method in Example 5). The bacterial suspension is prepared as follows: PP8 strain is inoculated into LB liquid medium and cultured at 30°C and 220 rpm for 16 hours. Ten soybean seeds are sown to form a bacterial suspension group, a fermentation broth group, and a control group. Each treatment is treated with 50 mL of bacterial suspension or sterile fermentation broth, while the control group is treated with water. The mixture is cultured at 25°C for 15 days.

[0073] The results are as follows Figure 9The results showed that the fresh weight of the irrigated Bacillus polymyxa PP8 bacterial solution and fermentation broth was slightly higher than that of the control group, and the fresh weight of the fermentation broth group was significantly higher than that of the control group.

[0074] Example 7: Colonization of Bacillus polymyxa PP8 in plants

[0075] First, induce the production of rifampicin-resistant mutant strains of Bacillus polymyxa PP8.

[0076] To further investigate the colonization of *Bacillus polymyxa* PP8 in different parts of soybean, 10 sterilized seeds were sown into sterilized vermiculite and irrigated with 50 mL of PP8 bacterial solution labeled with resistance. Eight days after root irrigation, samples were taken: 0.6 g each of roots, stems, and leaves were cut and surface-sterilized by soaking in 70% alcohol for 30 seconds, 2% sodium hypochlorite for 1 minute, and rinsing three times with sterile water. The samples were then ground and mixed in a mortar with 6 mL of sterile water. The supernatant was allowed to settle for 10 minutes and then diluted 10-fold to four concentrations (T1–T4). 0.1 mL of each concentration was spread onto LB agar plates containing 50 μg / mL rifampicin, with three replicates per concentration. The plates were incubated at 28°C for 2 days, and the colony count was recorded. The colony count per gram of fresh soybean tissue was calculated to evaluate colonization ability.

[0077] The results are as follows Figure 10 The results show that PP8 can colonize the roots, stems, and leaves of plants, but the highest number of colonies are found in the roots.

[0078] Example 8: Bacillus polymyxa PP8 can control diseases caused by various pathogens on a variety of plants.

[0079] The pathogenic fungus Fusarium graminearum ( Fusarium graminearum ) and soybean phytotoxicum ( Phytophthora sojae After the colonies have fully grown on 90mm plates, cut them into small pieces and mix them evenly into vermiculite. Inoculate two dishes of pathogens into each pot and sow 10 soybean seeds. Apply OD fertilizer on the day of inoculation and the fourth day after inoculation. 600 Use PP8 bacterial solution with a concentration of 1.0, and pour 50 mL of bacterial solution into each pot.

[0080] Similar to the above method, alfalfa was inoculated with Fusarium solani (… Fusarium solani ) and Fusarium oxysporum ( Fusarium oxysporum ), and inoculation of Fusarium oxysporum into Masson pine ( Fusarium oxysporum ).

[0081] The results are as follows Figure 11 and Figure 12 The results show that the application of Bacillus polymyxa PP8 can effectively prevent and control Fusarium rottenness (Fusarium rottenness). Fusarium solani ) and Fusarium oxysporum ( Fusarium oxysporum) caused by alfalfa ( Figure 11 ) and Masson pine ( Figure 12 Diseases on the surface.

[0082] Example 9 Field efficacy test of Bacillus polymyxa PP8

[0083] A 3m*3m plot was set up in the field, with two treatments. Treatment one was the OD (Original Demand) phase. 600 Treatment 1.0% bacterial solution, Treatment 2% was a microbial agent Bacillus subtilis (Bijian, manufacturer: Shanxi Linyi Zhongjin Chemical Co., Ltd.) diluted 800 times, and the control was water. All were applied at the time of seed sowing. After the soybeans matured, 10 plants were randomly selected from each plot, and the results were repeated three times. The number of pods per plant, the weight of grains per plant, the number of grains per plant, the weight of 100 grains, the mold rate, the shriveling rate, the plot yield, and the yield per acre were recorded.

[0084] The statistical results are shown in Table 1.

[0085] Table 1 Statistical Results of Field Indicators

[0086]

[0087] Meanwhile, the disease index and prevention and control effects were statistically analyzed based on the incidence and infection levels of purpura (Table 2).

[0088] Table 2 Infection Severity

[0089]

[0090] The results are as follows Figure 13 The results showed that applying Bacillus polymyxa PP8 increased soybean yield and had a better control effect on diseases.

[0091] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A plant endophytic polymyxa bacillus, characterized in that, The plant endophytic Bacillus polymyxa strain was numbered PP8 and classified as Bacillus polymyxa. Paenibacillus polymyxa The accession number is CGMCC No. 36638, and it was deposited at the China General Microbiological Culture Collection Center on November 17, 2025.

2. A microbial bactericide, characterized in that, The microbial bactericide contains the polymyxa bacillus described in claim 1.

3. The application of the plant endophytic polymyxa bacillus according to claim 1 or the microbial fungicide according to claim 2, characterized in that, The application is any of the following: A1) Promotes soybean growth; A2) Prepare products that promote soybean production; A3) Inhibits plant pathogens; A4) Prepare products that inhibit plant pathogens; A5) Nitrogen fixation, phosphorus dissolution, potassium decomposition, and / or iron carrier generation; A6) Prepare products that produce nitrogen fixation, phosphorus solubilization, potassium solubilization and / or iron carrier production; The plant pathogens include pathogenic fungi, pathogenic oomycetes, and pathogenic bacteria; The pathogenic fungus was selected from Fusarium graminearum (Fusarium graminearum). Fusarium graminearum Fusarium oxysporum ( Fusarium oxysporum Rhizoctonia solani ( ), Rhizoctonia solani Rhizoctonia solani Fusarium pseudograss () Fusarium pseudograminearum) Botrytis cinerea ( Botrytis cinerea Verticillium dahliae Verticillium dahliae ), Flathead anthrax bacteria ( Colletotrichum truncatum ), Sclerotinia sclerotiorum ( Sclerotinia sclerotiorum Fusarium solani () Fusarium solani One or more of the following; The pathogenic oomycete was selected from *Pythium tertrum* (… Pythium ultimum ), Phytophthora capsici ( Phytophthora capsici ), Phytophthora ( Phytophthora cactorum ), Phytophthora parasiticum ( Phytophthora parasitica ), soybean phytotoxicum ( Phytophthora sojae One or more of the following; The pathogenic bacteria were selected from Ralstonia solanacearum (Ralstonia solanacearum). Ralstonia solanacearum ), rice bacterial leaf streak ( Xanthomonas oryzae pv. oryzicola ), rice bacterial blight pathogen ( Xanthomonas oryzae pv. oryzae Kiwi fruit canker pathogen ( Pseudomonas syringae pv. actinidae ), *Pseudomonas syringae* tomato pathogenic strain ( Pseudomonas syringae pv. tomato One or more of the following.

4. A method for preventing and controlling plant diseases, characterized in that, The method includes treating a plant or a plant culture medium with the polymyxa bacillus of claim 1 or the microbial fungicide of claim 2; the plant disease is caused by at least one pathogen of claim 3, and the plant is soybean, alfalfa or Masson pine.

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