Bacillus velezensis RMM03 and application of product of bacillus velezensis RMM03 in preventing and treating rice false smut

Abstract

The invention discloses bacillus velezensis RMM03 and application of a product of the bacillus velezensis RMM03 in preventing and treating rice false smut. The invention discloses bacillus velezensis RMM03 which is preserved in Guangdong Province Microbial Culture Collection Center on November 19, 2024, the preservation address is 5th floor, No.59 building, No.100 Courtyard, Xianlie Middle Road, Guangzhou, and the preservation number is GDMCC No.65510. The bacillus velezensis RMM03 is named as bacillus velezensis RMM03. The bacillus velezensis RMM03 is named as bacillus velezensis RMM03. Indoor and field tests show that the strain has a remarkable inhibition effect on the growth of rice ustilaginoidea virens, prevention and treatment can be carried out 10-15 days before crevasse, 0-5 days before crevasse and 0-5 days after heading, the prevention and treatment time span is long, and high yield and high quality of rice are effectively guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of microorganisms, and in particular relates to application of Bacillus velezensis RMM03 and products thereof in preventing and controlling rice false smut. Background Art

[0002] Rice false smut is a panicle disease caused by the fungus Ustilaginoidea virens. Its typical symptom is the formation of dark green or yellowish-green spherical sclerotia (rice smut balls) on rice grains during the grain filling stage, containing numerous thick-walled spores. These spores not only reduce rice yield and quality but also produce toxins (such as fusin), posing a health threat to humans and animals.

[0003] Rice smut primarily invades rice during the flowering stage, becomes apparent during the grain filling phase, and becomes a major devastation during the ripening phase. Without control measures, the incidence of rice smut can reach as high as 80-100%. Currently, chemical control is still the primary method of treatment. However, due to the short control window, timing is critical. Application must be made 5-7 days before heading, or before rice smut breaks. Application earlier or later than this time is ineffective. During the 5-7 days before rice smut breaks, the rainy season in southern regions like Zhejiang Province is in full swing, and continuous rainfall prevents pesticides from fully exerting their effectiveness, resulting in ineffective control. To effectively control rice smut, farmers frequently use chemical pesticides, increasing production costs and the risk of pesticide residue contamination in the rice and the environment.

[0004] Active microbial biocontrol agents are an ideal alternative to chemical pesticides due to their environmental safety, pollution-free nature, and residue-free properties. To this end, Chinese invention patent application CN118773059A discloses a strain of Bacillus velezensis and its applications. This strain, deposited under CCTCC M20241090, exhibits an inhibition zone of 33.56 mm against U. oryzae var. oryzae, with an inhibition rate of 61.00%.

[0005] Chinese invention patent application with publication number CN114317329A discloses a Bacillus subtilis strain, its screening method and application. The description of the application records that the potted control efficacy of Bacillus velezensis is 57.69±0.13c and the field control efficacy is 56.42±0.60c.

[0006] Chinese invention patent application publication number 118497045A discloses a low-temperature straw-degrading bacterium that effectively inhibits crop pathogenic fungi and its applications. The low-temperature straw-degrading bacterium is Bacillus velezensis BD3, with a GDMCC accession number of 64386. The strain has an inhibition rate of 92.47±0.35% against rice smut fungus.

[0007] However, current biocontrol agents have very high control time requirements, requiring them to be applied 5-7 days before rice ruptures to be effective. This short control time of only three days makes the control of rice false smut difficult. Summary of the Invention

[0008] The purpose of the present invention is to provide an application of Bacillus Velezii RMM03 and its products in preventing and controlling rice false smut. The strain of the present invention has a significant inhibitory effect on the growth of rice false smut fungi and can prevent and control rice false smut in three time periods, with a long prevention and control time span.

[0009] In order to solve the problems existing in the prior art, the technical solution adopted by the present invention is:

[0010] In a first aspect, the present invention provides a strain of Bacillus velezensis RMM03,

[0011] A strain of Bacillus velezensis RMM03 was deposited in Guangdong Provincial Microbiological Culture Collection Center with a deposit date of November 19, 2024. The deposit address is: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou City, and the deposit number is GDMCC No. 65510.

[0012] In a second aspect, the present invention provides use of the Bacillus Velezii described in the first aspect in preparing a product for preventing and controlling rice false smut.

[0013] Specifically, the product is a biocontrol agent.

[0014] In a third aspect, the present invention provides a biocontrol agent, wherein the biocontrol agent contains the Bacillus Velezii described in the first aspect, and the number of viable bacteria in the biocontrol agent is 1×10 5 cfu / mL-1×10 10 cfu / mL.

[0015] Furthermore, the invention also comprises a protective agent and sterile water, wherein the protective agent is one or more of carboxymethyl cellulose, methyl cellulose, starch, cyclodextrin, chitosan and lignin; and the concentration of the protective agent in the biocontrol agent is 1-10% (m / m).

[0016] In a fourth aspect, the present invention provides a method for preparing the biocontrol agent described in the third aspect, comprising the following steps:

[0017] ① Inoculate Bacillus velezensis RMM03 into LB liquid medium, place in a constant temperature shaker at 26-35°C, shake and ferment for 24-60 hours to obtain a fermentation liquid;

[0018] ② Add protective agent and sterile water, and adjust the concentration of the fermentation liquid to a viable bacterial count of 1×10 5 cfu / mL-

[0019] 1×10 10 cfu / mL.

[0020] In a fifth aspect, the present invention provides a method for preventing rice false smut, comprising the following steps:

[0021] Spray the biocontrol agent described in the third aspect or the biocontrol agent prepared according to the method described in the fourth aspect 15 days before rice rupture and 5 days after heading, and the spraying concentration of the biocontrol agent is 1×10 5 cfu / mL-1×10 10 cfu / mL. If it rains within 4 hours after application, apply the pesticide again at the same spraying concentration after the rain stops.

[0022] Furthermore, the period 15 days before rice rupture - 5 days after heading refers to 10-15 days before rice rupture, 0-5 days before rice rupture or 0-5 days after heading, preferably 10-15 days before rice rupture.

[0023] Furthermore, the biocontrol agent described in the third aspect or the biocontrol agent prepared according to the method described in the fourth aspect is sprayed 10-15 days before the rice breaks, with a spraying concentration of 1×10 5 cfu / mL-1×10 7 cfu / mL.

[0024] Furthermore, the biocontrol agent described in the third aspect or the biocontrol agent prepared according to the method described in the fourth aspect is sprayed 0-5 days before rice rupture or 0-5 days after heading. It is necessary to spray once more 3 days after the first spraying, and the spraying concentration is 1×10 8 cfu / mL-1×10 10 cfu / mL.

[0025] Preservation Instructions:

[0026] Strain name: Bacillus velezensis RMM03;

[0027] Deposit number: GDMCC No.65510;

[0028] Taxonomic name: Bacillus velezensis;

[0029] Deposit date: November 19, 2024;

[0030] Depository: Guangdong Provincial Microbial Culture Collection Center;

[0031] Collection address: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou.

[0032] The advantages and beneficial effects of the present invention are:

[0033] The Bacillus Velezii RMM03 of the present invention is isolated from the soil of a rice false smut disease-occurring plot and obtained through indoor confrontation test screening. Indoor and field tests show that the bacterium has a significant inhibitory effect on the growth of rice false smut disease fungi, and can be used for prevention and control 10-15 days before rice blast, 0-5 days before rice blast, and 0-5 days after heading. The prevention and control time span is long, and the high and high yield of rice is effectively guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The antagonistic effect of the strain RMM03 of the present invention on rice rust (5 days after inoculation) is shown in Figure 5. A shows the growth of rice rust (Ustilaginoidea virens) on PDA medium; B shows the growth of rice rust on PDA medium containing RMM03.

[0035] Figure 2 This is the colony morphology of the strain RMM03 of the present invention;

[0036] Figure 3 This figure shows the control effect of the biocontrol agent with the strain RMM03 of the present invention as the main component on rice false smut in the field. In the figure: a is the rice ear before control, and b is the rice ear after control. DETAILED DESCRIPTION

[0037] The following will be combined with the accompanying drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0038] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0039] LB liquid medium: 10 g of tryptone, 5 g of yeast extract, 10 g of sodium chloride, and distilled water to 1000 ml, adjust the pH to 7.0-7.2, and sterilize at 121°C.

[0040] LB solid plate medium: Add agar powder with a concentration of 15g / L to the LB liquid medium.

[0041] PDA solid plate medium: 200 g potatoes, 20 g glucose, distilled water to 1000 ml, add agar powder at a concentration of 15 g / L, and sterilize at 121°C.

[0042] Example 1 Isolation, purification and identification of antagonistic bacteria RMM03

[0043] 1. Bacterial isolation and initial screening

[0044] Soil was collected from a rice field (Yongyou 31) with false smut in Yuecheng District, Shaoxing City, Zhejiang Province, sealed in sterile ziplock bags, brought back to the laboratory, and stored at 4°C for isolation of single colonies.

[0045] The target pathogen was Ustilaginoidea virens, isolated by the present invention team from rice plants in the diseased area of rice (Yongyou 31) in Yuecheng District, Shaoxing City, Zhejiang Province. The bacterial culture medium was LB liquid medium, and the fungal culture medium was PDA solid plate medium.

[0046] The soil dilution method was used to isolate the bacteria, and continuous streaking culture was performed until pure. The growth rate index was used to determine the antagonistic effect of bacteria on rice rust. A 5mm diameter puncher was used to prepare rice rust cakes, which were inoculated on PDA plates (control group) and PDA plates premixed with antagonistic bacteria (antagonistic group), and cultured in the dark in a 28°C biochemical incubator for 8 days. By measuring the growth diameter of the rice rust in the antagonistic group, the strain RMM03 with a significant antagonistic effect compared with the control group was preserved. The results of the plate antagonism of the antagonistic bacteria RMM03 against rice rust are shown in Figure 2. Figure 1 As shown, Figure 1 A shows the growth status of the rice urticaria in the control group on PDA medium. Figure 1 B shows the growth status of U.S. oryzae on PDA medium containing antagonistic bacteria RMM03. Figure 1 It can be seen that in the antagonistic bacteria RMM03 antagonistic group, the rice rust fungus basically did not grow, and the effect was the most prominent.

[0047] 2. Strain identification

[0048] 2.1 Morphological identification:

[0049] like Figure 2 As shown, the colony morphology of the antagonistic bacteria RMM03 is: smooth surface, loose colonies, bifurcated and loose lines, and light yellow.

[0050] 2.2 Molecular biological methods were used to identify the antagonistic strain RMM03.

[0051] PCR amplification was performed using universal primers for bacterial identification 16S rDNA (27F and 1492R):

[0052] PCR reaction system (50 μL system): 2 μL of each primer, 25 μL of 2× Mix, and add ddH2O to make up to 50 μL.

[0053] The 16S rDNA primer sequences were 27F: (5'-AGAGTTT GATCCTGGCTCAG-3') (SEQ ID NO. 1) and 1492R: (5'-GGTTACCTTGTTACGACTT-3') (SEQ ID NO. 2). The reaction procedure was as follows: 94°C pre-denaturation for 3 min, 94°C denaturation for 55 s, 50°C annealing for 50 s, 72°C extension for 1 min, and 72°C extension for 10 min, followed by 35 cycles of storage at 16°C. The PCR products were analyzed on 1.5% agarose gel electrophoresis and sent to Beijing Qingke Biotechnology Co., Ltd. for 16S rDNA sequencing. The 16S rDNA gene sequence of the antagonist bacterium RMM03 is shown in SEQ ID NO. 3. The sequence was compared using BLAST comparison with the Eziocloud database, confirming that the antagonist bacterium RMM03 was Bacillus velezensis. The strain was deposited in Guangdong Provincial Microbial Culture Collection Center, with the deposit address at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, with the deposit number GDMCC No. 65510 and the deposit date being November 19, 2024. SEQ ID NO. 3:

[0054] ACGCTGGCGGCGTGCCTAATACATGCAAGTCGAGCGGACAGATGGGAGCTTGCTCCCTGATGTTAGCGGCGGACGG

[0055] GTGAGTAACACGTGGGTAACCTGCCTGTAAGACTGGGATAACTCCGGGAAACCGGGGCTAATACCGGATGGTTGTC

[0056] TGAACCGCATGGTTCAGACATAAAAGGTGGCTTCGGCTACCACTTACAGATGGACCCGCGGCGCATTAGCTAGTTG

[0057] GTGAGGTAACGGCTCACCAAGGCGACGATGCGTAGCCGACCTGAGAGGGTGATCGGCCACACTGGGACTGAGACAC

[0058] GGCCCAGACTCCTACGGGAGGCAGCAGTAGGGAATCTTCCGCAATGGACGAAAGTCTGACGGAGCAACGCCGCGTG

[0059] AGTGATGAAGGTTTTCGGATCGTAAAGCTCTGTTGTTAGGGAAGAACAAGTGCCGTTCAAATAGGGCGGCACCTTG

[0060] ACGGTACCTAACCAGAAAGCCACGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGGTGGCAAGCGTTGTCCG

[0061] GAATTATTGGGCGTAAAGGGCTCGCAGGCGGTTTCTTAAGTCTGATGTGAAAGCCCCCGGCTCAACCGGGGAGGGT

[0062] CATTGGAAACTGGGGAACTTGAGTGCAGAAGAGGAGAGTGGAATTCCACGTGTAGCGGTGAAATGCGTAGAGATGT

[0063] GGAGGAACACCAGTGGCGAAGGCGACTCTCTGGTCTGTAACTGACGCTGAGGAGCGAAAGCGTGGGGAGCGAACAG

[0064] GATTAGATACCCTGGTAGTCCACGCCGTAAACGATGAGTGCTAAGTGTTAGGGGGTTTCCGCCCCTTAGTGCTGCA

[0065] GCTAACGCATTAAGCACTCCGCCTGGGAGTACGGTCGCAAGACTGAAACTCAAAGGAATTGACGGGGGCCCGCAC

[0066] AAGCGGTGGAGCATGTGGTTTAATTCGAAGCAACGCGAAGAACCTTACCAGGTCTTGACATCCTCTGACAATCCTA

[0067] GAGATAGGACGTCCCCTTCGGGGGCAGAGTGACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGTTGG

[0068] GTTAAGTCCCGCAACGAGCGCAACCCTTGATCTTAGTTGCCAGCATTCAGTTGGGCACTCTAAGGTGACTGCCGGT

[0069] GACAAACCGGAGGAAGGTGGGGATGACGTCAAATCATCATGCCCCTTATGACCTGGGCTACACACGTGCTACAATG

[0070] GACAGAACAAAGGGCAGCGAAACCGCGAGGTTAAGCCAATCCCACAAATCTGTTCTCAGTTCGGATCGCAGTCTGC

[0071] AACTCGACTGCGTGAAGCTGGAATCGCTAGTAATCGCGGATCAGCATGCCGCGGTGAATACGTTCCCGGGCCTTGT

[0072] ACACACCGCCCGTCACACCACGAGAGTTTGTAACACCCGAAGTCGGTGAGGTAACCTTTATGGAGCCAGCCGCCGA

[0073] AGGTGGGACAGATGATTGGGGTGAAGT

[0074] Example 2

[0075] This embodiment provides a biocontrol agent, the preparation method of which comprises the following steps:

[0076] ① Inoculate Bacillus velezensis RMM03 into LB liquid culture medium and culture in a constant temperature shaker at 28°C and 200 rpm for 36 h to obtain a fermentation broth.

[0077] ② Add protective agent and sterile water to the fermentation liquid and adjust the concentration of the fermentation liquid to a viable bacterial count of 1×10 9 cfu / ml, and a biocontrol agent is obtained. The protective agent is starch and lignin, the mass ratio of the starch to the lignin is 1:1, and the concentration of the protective agent in the biocontrol agent is 6% (m / m).

[0078] Example 3

[0079] This embodiment provides a biocontrol agent. The only difference between this embodiment and Example 2 is that the protective agent used is methyl cellulose. The rest is the same as Example 2.

[0080] Example 4

[0081] This embodiment provides a biocontrol agent. The only difference between this embodiment and Example 2 is that the protective agent used is lignin. The rest is the same as Example 2.

[0082] Example 5

[0083] This embodiment provides a biocontrol agent. The only difference between this embodiment and Example 2 is that the protective agent used is carboxymethyl cellulose. The rest is the same as Example 2.

[0084] Example 6

[0085] This embodiment provides a biocontrol agent. The only difference between this embodiment and Example 2 is that the protective agent used is chitosan. The rest is the same as Example 2.

[0086] Example 7

[0087] This embodiment provides a biocontrol agent. The only difference between this embodiment and embodiment 2 is that the concentration of the protective agent in the biocontrol agent is 1% (m / m). The rest is the same as embodiment 2.

[0088] Example 8

[0089] This embodiment provides a biocontrol agent. The only difference between this embodiment and embodiment 2 is that the concentration of the protective agent in the biocontrol agent is 10% (m / m). The rest is the same as embodiment 2.

[0090] Comparative Example 1

[0091] This comparative example provides a biocontrol agent, which is commercially available Bacillus Velezii C17271 (produced by Zhejiang Sairui Ke Cell Technology Co., Ltd.).

[0092] Comparative Example 2

[0093] This comparative example provides a biocontrol agent. The only difference between this comparative example and Example 2 is that sodium lignin sulfonate is used instead of lignin in step ② of this comparative example. The rest is the same as Example 2.

[0094] Comparative Example 3

[0095] This comparative example provides a biocontrol agent. The only difference between this example and Example 2 is that there is no protective agent. In step ② of this example, only sterile water is added to the fermentation broth. The rest is the same as in Example 2.

[0096] Example 9

[0097] This embodiment provides a method for preventing and controlling rice false smut, comprising the following steps:

[0098] 10-15 days before the rice breaks, the biocontrol agent described in Example 2 was sprayed at a concentration of 1×10 5 cfu / mL-1×10 7 cfu / mL. If it rains within 4 hours after application, apply the pesticide once more at the same spraying concentration after the rain stops. Application time: in the evening when the temperature does not exceed 30℃.

[0099] Example 10

[0100] This embodiment provides a method for preventing and controlling rice false smut, comprising the following steps:

[0101] 0-5 days before the rice breaks, the biocontrol agent described in Example 2 was sprayed at a concentration of 1×10 8 cfu / mL-1×10 10 cfu / mL. If it rains within 4 hours after spraying, apply the same spray concentration once after the rain stops. Application time: evening, when the temperature does not exceed 30°C. Apply the same spray concentration again 3 days after the first spraying.

[0102] Example 11

[0103] This embodiment provides a method for preventing and controlling rice false smut, comprising the following steps:

[0104] The biocontrol agent described in Example 2 was sprayed 0-5 days after rice heading, and the spraying concentration of the biocontrol agent was 1×10 8 cfu / mL-1×10 10 cfu / mL. If it rains within 4 hours after spraying, apply the same spray concentration once after the rain stops. Application time: evening, when the temperature does not exceed 30°C. Apply the same spray concentration again 3 days after the first spraying.

[0105] Experimental Example 1 Field test of the biocontrol agent of the present invention against rice false smut

[0106] 1.1 Overview of the experimental site: From August to September 2024, a prevention and control experiment was carried out in rice fields infected with rice false smut. The experimental site was Shanghuizao Village, Lanting Street, Keqiao District, Shaoxing City, Zhejiang Province. The fertility of the experimental rice fields was well managed, and the experimental field area was 10 mu.

[0107] 1.2 Experimental Grouping: The experimental field was divided into four large areas, namely the clear water control area and three experimental areas. A 2-meter rice separation zone was reserved between each area. The area of the clear water control area was 10m 2 Each experimental area was set up with 10 treatments, including the biocontrol agent group prepared in Examples 2-8 and the control agent group prepared in Comparative Examples 1-3. Each treatment was repeated three times, that is, each experimental area had 30 plots, each plot had an area of 10m2 All experimental plots were planted in the same pattern. During the trial, fertilizer and fertilization management was maintained as normal in each plot. Cultivation, fertilizer and water management, and weed control practices were consistent with local rice production. The rice variety tested was Yongyou 31.

[0108] Test method:

[0109] Clean water control area: No pesticides were applied during the entire growth period, and only clean water was sprayed during the test.

[0110] Experimental area 1: The control was carried out 10-15 days before the rice burst. The specific application time of this experiment was: the evening of August 20, 2024, when the temperature did not exceed 30℃. The spraying concentration was 1×10 7 cfu / mL.

[0111] Experimental area 2: Control was carried out 0-5 days before the rice burst, and the pesticide was applied twice. The specific application time of this experiment was September 2 and September 5, 2024, in the evening when the temperature did not exceed 30℃. The spraying concentration was 1×10 9 cfu / mL.

[0112] Experimental area 3: The control was carried out 0-5 days after the rice heading, and the pesticide was applied twice. The specific application time of this experiment was: September 8 and September 11, 2024, in the evening, when the temperature did not exceed 30℃. The spraying concentration was 1×10 9 cfu / mL.

[0113] 3. Rice False Smut Control Survey: On September 20th, a survey was conducted in each plot. A random sampling method was used at five locations within each plot. Ten rice ears were sampled at each location, and the number of diseased grains was recorded to calculate the control rate. The statistical results are shown in Tables 1-4.

[0114] Grain prevention effect (%) = (number of diseased grains in the control area - number of diseased grains in the treated area) / (number of diseased grains in the control area) × 100%.

[0115] Figure 3 The control effect of the biological agent prepared in Example 2 in experimental area 3 is shown in FIG. Figure 3 As shown in the figure, the rice panicles had suffered from serious rice false smut before the prevention and control, and the rice false smut balls had developed into shape ( Figure 3 a), 7 days after the second spraying of the biological agent prepared by the present invention, the further development of rice koji fungi has been successfully inhibited, and the rice koji balls have shrunk and fallen off ( Figure 3 b).

[0116] Table 1: The efficacy of one pill in the experimental area (%)

[0117]

[0118] Table 2: The efficacy of 2 tablets in the experimental area (%)

[0119]

[0120]

[0121] Table 3: Control effect of 3 pills in the experimental area (%)

[0122]

[0123] Table 4: Control group of water for preventing and controlling granules (%)

[0124]

[0125] As can be seen from Tables 1-4, the biological agent using Bacillus Velezii RMM03 as the main active ingredient was sprayed 15 days before rice rupture and 5 days after heading, which had a relatively good control effect on rice false smut. By comparing Examples 2-8 with Comparative Example 3, it can be seen that after adding a protective agent to the antagonistic bacteria RMM03, the control effect was greatly improved.

[0126] As shown in Tables 1 to 4, spraying the biocontrol agent described in Comparative Example 1 10-15 days before rice rupture has a certain control effect on rice false smut, but the control effect is greatly reduced when spraying 0-5 days before rupture and 0-5 days after heading.

[0127] It can be seen from Tables 1 to 4 that the control effect of rice false smut in Comparative Example 2 is greatly reduced due to the use of sodium lignin sulfonate instead of lignin.

[0128] As shown in Tables 1 to 4, in Comparative Example 3, due to the lack of a protective agent, a large number of Bacillus Velezii RMM03 died due to difficulty in adapting to environmental conditions and could not exert a control effect.

[0129] In summary, the biological agent of the present invention not only has a very good control effect on rice false smut, but also broadens the control time of rice false smut from the traditional 5-7 days before rice smut to 15 days before rice smut - 5 days after heading, which greatly reduces the difficulty and intensity of rice false smut control work and improves the control effect of rice false smut.

[0130] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

Claims

1. A strain of Bacillus velezinoffii ( Bacillus velezensis ) RMM03, which features: It is deposited in Guangdong Provincial Microbiological Culture Collection Center, the deposit date is November 19, 2024, the deposit address is: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, and the deposit number is GDMCC No.65510.

2. Use of the Bacillus Velezii according to claim 1 in preparing a product for preventing and treating rice false smut.

3. The product according to claim 2, characterized in that: The product is a biocontrol agent.

4. A biocontrol agent, characterized in that: The biocontrol agent contains the Bacillus Velezii according to claim 1, and the number of viable bacteria in the biocontrol agent is 1×10 5 cfu / mL-1×10 10 cfu / mL.

5. The biocontrol agent according to claim 4, characterized in that: The biocontrol agent further comprises a protective agent and sterile water. The protective agent is one or more of carboxymethyl cellulose, methyl cellulose, starch, cyclodextrin, chitosan and lignin. The concentration of the protective agent in the biocontrol agent is 1-10% (m / m).

6. The method for preparing the biocontrol agent according to any one of claims 4 to 5, characterized in that: The following steps are involved: ① Inoculate Bacillus velezensis RMM03 into LB liquid medium, place in a constant temperature shaker at 26-35°C, and ferment for 24-60 hours to obtain a fermentation liquid; ② Add protective agent and sterile water, and adjust the concentration of the fermentation liquid to a viable bacterial count of 1×10 5 cfu / mL-1×10 10 cfu / mL.

7. A method for preventing and controlling rice false smut, characterized in that: The following steps are involved: Spray the biocontrol agent according to any one of claims 4-5 or the biocontrol agent prepared according to the method of claim 6 15 days before rice rupture and 5 days after heading, wherein the spraying concentration of the biocontrol agent is 1×10 5 cfu / mL-1×10 10 cfu / mL.

8. The method for preventing and controlling rice false smut according to claim 7, wherein: The period of 15 days before rice rupture - 5 days after heading refers to 10-15 days before rice rupture, 0-5 days before rice rupture or 0-5 days after heading, preferably 10-15 days before rice rupture.

9. The method for preventing and controlling rice false smut according to claim 8, wherein: The biocontrol agent according to any one of claims 4 to 5 or the biocontrol agent prepared according to the method of claim 6 is sprayed 10 to 15 days before the rice breaks, with a spraying concentration of 1×10 5 cfu / mL-1×10 7 cfu / mL.

10. The method for preventing and controlling rice false smut according to claim 8, wherein: Spray the biocontrol agent according to any one of claims 4-5 or the biocontrol agent prepared according to the method of claim 6 0-5 days before rice rupture or 0-5 days after heading, and spray once more 3 days after the first spraying, with a spraying concentration of 1×10 8 cfu / mL-1×10 10 cfu / mL.

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