Lysinibacillus sphaericus for preventing and treating root rot of lycium barbarum and application thereof

Abstract

The present application belongs to the technical field of microbial pesticides, and particularly relates to a biocontrol actinomycete for preventing and treating root rot of wolfberry and application thereof. The biocontrol actinomycete for preventing and treating root rot of wolfberry is S. flavofungini NA05, the preservation number of which is CGMCC No. 29739, the preservation date is January 23, 2024, and the preservation address is China General Microbiological Culture Collection Center. The S. flavofungini NA05 has a significant inhibitory effect on various pathogenic bacteria of root rot of wolfberry, can regulate the rhizosphere microecology of diseased wolfberry to resist the occurrence of root rot, and is expected to be used for developing a targeted drug and a biocontrol agent for treating root rot of wolfberry.

Description

Technical Field

[0001] This invention belongs to the field of microbial pesticide technology, specifically relating to a biocontrol actinomycete for controlling root rot of wolfberry and its application. Background Technology

[0002] Goji berries ( Lycium barbarum Lycium (L.) is a perennial deciduous shrub belonging to the genus Lycium in the Solanaceae family. It is a traditional Chinese medicinal herb and occupies a very important position in the development of traditional Chinese medicine. In recent years, the occurrence of diseases affecting Lycium has been increasing year by year. Among them, root rot is one of the major diseases in Ningxia Lycium cultivation, causing significant losses to production and seriously restricting the sustainable development of the industry. There are many types of pathogens causing Lycium root rot, and the occurrence of root rot is often caused by the combined infection of multiple pathogens. The types of pathogens causing root rot in Ningxia Lycium are gradually increasing with the updating of Lycium varieties and changes in planting methods. Chemical agents have some effect on the control of root rot, but the effect is not ideal; in addition, excessive addition may change the properties of the soil, and more seriously, may damage the soil and ecological environment, posing a significant safety hazard. Biological control is receiving increasing attention due to its advantages such as good efficacy, low cost, high efficiency, environmental friendliness, and no drug residues.

[0003] The rhizosphere of plants harbors abundant microbial resources, many of which possess growth-promoting and biocontrol functions. Obtaining microbial resources with strong inhibitory effects against the pathogen causing wolfberry root rot from the rhizosphere is a key focus of biocontrol research on wolfberry root rot. Currently, there are many types of antagonistic microorganisms used for plant disease control, including actinomycetes, Bacillus, and Pseudomonas, but reports specifically targeting antagonistic bacteria against wolfberry root rot are limited. Existing reports mainly focus on bacteria and fungi, including Bacillus amyloliquefaciens (B. amyloliquefaciens). Bacillus amyloliquefaciens ), Chinese rhizobium ( Sinorhizobium sp.), Metarhizium anisopliae ( Metarhizium sp.), Root Root Sporocysts ( Rhizophagus intraradices Regarding the antagonistic effect of actinomycetes on the pathogen causing root rot in wolfberry, there are very few reports. Actinomycetes produce abundant secondary metabolites that can effectively inhibit bacteria, fungi, viruses, and nematodes that harm crops. They were among the first biocontrol microorganisms applied in actual production and have significant value in biological control. Obtaining microbial resources from the rhizosphere of wolfberry for the control of root rot is of great significance for the prevention and control of wolfberry root rot. It can effectively solve the problem of efficient colonization of key microorganisms in inoculants and the ecological security risks brought about by the introduction of alien species. Furthermore, antagonistic screening against multiple wolfberry pathogens can ensure the control effect of inoculants on root rot. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a biocontrol actinomycete for preventing and controlling root rot of wolfberry and its application.

[0005] To achieve this objective, the present invention employs the following technical solution: a biocontrol actinomycete for preventing and controlling root rot in wolfberry, wherein the biocontrol actinomycete for preventing and controlling root rot in wolfberry is *Streptomyces flavovirens* (…). S. flavofungini NA05, the biocontrol actinomycete for controlling root rot of wolfberry is *Streptomyces flavovirens* (NA05). S. flavofungini NA05, accession number CGMCC No.29739, accession date January 23, 2024, accession address China General Microbiological Culture Collection Center.

[0006] In some embodiments of the present invention, the yellow-antimycin-containing Streptomyces NA05 has an earthy odor, opaque colonies, and a dry colony surface.

[0007] On the other hand, the present invention provides the application of the biocontrol actinomycetes for preventing and controlling wolfberry root rot in the prevention and control of wolfberry root rot, wherein the yellow-resistant streptomycin NA05 has a significant inhibitory effect on the pathogenic fungi of wolfberry root rot.

[0008] In some embodiments of the present invention, the application of the biocontrol actinomycetes for controlling wolfberry root rot in the control of wolfberry root rot includes the pathogenic fungi of wolfberry root rot such as Rhizoctonia solani, Fusarium oxysporum, Fusarium floridum, Fusarium solani, Fusarium rosenbergii, Fusarium moniliforme, Fusarium rosenbergii, and Fusarium rosenbergii.

[0009] In some embodiments of the present invention, the application of the biocontrol actinomycetes for preventing and controlling wolfberry root rot involves using the conidia of the yellow-antimycin-resistant Streptomyces NA05 as the active ingredient, either directly or processed into a formulation, for the prevention and control of wolfberry root rot.

[0010] In some embodiments of the present invention, the application of the biocontrol actinomycetes for preventing and controlling root rot of wolfberry in the prevention and control of root rot of wolfberry includes preparations such as liquid inoculants, powders, and granules.

[0011] On another aspect, the present invention provides the application of the biocontrol actinomycetes for preventing and controlling root rot of wolfberry in improving the stability of the microecological community structure. The application of the yellow-resistant streptomycin NA05 to the soil of diseased wolfberry significantly reduces the abundance of pathogens in the rhizosphere and root surface of wolfberry and significantly increases the abundance of beneficial bacteria.

[0012] The beneficial effects of this invention are as follows:

[0013] (1) The biocontrol actinomycete for controlling root rot of wolfberry provided by the present invention is *Streptomyces flavovirens* (a type of *Streptomyces flavovirens*). S. flavofungini NA05 has a significant inhibitory effect on a variety of pathogens causing root rot. The effectiveness of strain NA05 against root rot of wolfberry was verified through pot experiments.

[0014] (2) The biocontrol actinomycetes for controlling root rot of wolfberry provided by the present invention ( S. flavofungini NA05, its fermentation broth, after high-temperature sterilization, still has a significant inhibitory effect on the mycelial growth of various pathogenic fungi, with the highest antibacterial efficiency reaching 70%.

[0015] (3) The introduction of NA05 strain into the soil has a positive regulatory effect on the community structure of bacteria and fungi in the rhizosphere and root surface of wolfberry. It can significantly reduce the abundance of pathogens in the rhizosphere and root surface soil of wolfberry, while the abundance of beneficial bacteria is significantly increased.

[0016] It is evident that strain NA05 has a significant inhibitory effect on multiple pathogens causing root rot in wolfberry. Its active metabolites can withstand high temperatures and can regulate the soil microecology of wolfberry, resisting the occurrence of root rot. It is expected to be developed into a targeted drug and biocontrol agent for the treatment of root rot in wolfberry. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 Colony morphology of strain NA05 on different culture media;

[0019] Figure 2 Phylogenetic tree constructed based on gene sequences of rRNA, atpD, recA, gyrB, rpoB, trpB, etc.

[0020] Figure 3 The inhibitory effect of strain NA05 and its 3d and 5d fermentation broths on the growth of pathogenic fungi;

[0021] Figure 4 Pot experiment to verify the control effect of strain NA05 on root rot of wolfberry;

[0022] Figure 5 : Door level ( Figure 5 a, Figure 5 b) and genus level ( Figure 5 c. Figure 5 d) Composition and relative abundance of fungi in the upper root surface and rhizosphere;

[0023] Figure 6 : Door level ( Figure 6 a, Figure 6 b) and genus level ( Figure 6 c. Figure 6 d) Composition and relative abundance of bacteria in the upper root surface and rhizosphere. Detailed Implementation

[0024] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0025] The present invention provides a biocontrol actinomycete for controlling root rot of wolfberry, wherein the biocontrol actinomycete for controlling root rot of wolfberry is *Streptomyces flavovirens* (…). S. flavofungini NA05, the biocontrol actinomycete for controlling root rot of wolfberry is *Streptomyces flavovirens* (NA05). S. flavofungini NA05, accession number CGMCC No. 29739, accession date January 23, 2024, accession address China General Microbiological Culture Collection Center.

[0026] To address the shortcomings of existing methods in the prevention and control of root rot in wolfberry, this invention utilizes Rhizoctonia solani (… Rhizoctonia solani Fusarium oxysporum ( Fusarium oxysporum ), Fragrant Fusarium ( F. redolens Fusarium solani () F. solani Fusarium moniliforme ( ) F. proliferatum Fusarium rosenbergii ( ), F. incarnatum Fusarium oxysporum ( ), F. andiyazi Fusarium moniliforme () F. moniliforme More than 10 pathogens causing root rot in wolfberry, including *Fusarium oxysporum* and *Fusarium oxysporum*, were used as test pathogenic fungi. Actinomycete NA05, which showed good antagonistic activity against multiple pathogens causing wolfberry root rot, was isolated and screened from the rhizosphere soil of *Lycium barbarum* var. *ningerii*. The taxonomic position of strain NA05 was further identified as *Streptomyces flavonoides* (*Fusarium oxysporum*) using physiological and biochemical indicators and multiple gene fragments including 16S rRNA, gyrB, trpB, recA, rpoB, and atpD. S. flavofungini The study compared the inhibitory effects of NA05 fermentation broth on the mycelial growth of pathogens under different treatments and demonstrated that its antibacterial substances have certain heat resistance. It also clarified the positive regulatory effect of the strain on the composition and diversity of microbial communities in the rhizosphere and root surface soil of wolfberry, thus expanding the resources of more microbial strains for the biological control of wolfberry root rot.

[0027] Preferably, the method is as follows: strain NA05 is inoculated into TSB medium and cultured at 28°C and 150 r / min for 7 days. The fermentation broth is centrifuged at 8000 r / min for 5 min, and the supernatant is filtered through a 0.22 μm microporous membrane to obtain sterile fermentation filtrate. The fermentation broth is then sterilized at 121°C for 30 min. The sterile fermentation broths obtained from the two treatments are added to the culture medium. Plates prepared by mixing 2×PDA and ordinary TSB in a 1:1 ratio are used as the control group. After inoculation with pathogens, the colony diameter is measured using the cross-cross method, and the inhibition rate of each fermentation broth on pathogen mycelia is calculated.

[0028] The extracellular metabolites of the antagonistic bacterium NA05 play an important role in inhibiting pathogens. Figure 3 ).

[0029] The antagonistic bacterium NA05, when introduced into wolfberry plants simultaneously with the pathogen, can inhibit or slow down the occurrence of wolfberry root rot and improve the symptoms of root rot in wolfberry plants. Figure 4 ).

[0030] The antagonistic bacterium NA05, when inoculated into the soil of potted wolfberry plants, can regulate the rhizosphere microecology of wolfberry and resist the occurrence of root rot disease. Figure 5 , Figure 6 (Tables 3 and 4).

[0031] Preferably, pot experiments were first used to verify that the inoculation of strain NA05 inhibited the occurrence of root rot in wolfberry or alleviated the symptoms of root rot. Secondly, high-throughput sequencing technology was used to show that after simultaneous inoculation of strain NA05 and the pathogen, the diversity indices of fungi on the root surface and rhizosphere of wolfberry were superior to the control group inoculated only with the pathogen. The diversity of root surface bacteria was also superior to the control group inoculated only with the pathogen. This was mainly reflected in the significant decrease in the abundance of Fusarium in wolfberry roots and the increase in the abundance of beneficial bacteria such as *Morchella* and *Bacillus* after simultaneous inoculation of strain NA05 and the pathogen.

[0032] Example 1: Isolation and identification of Streptomyces NA05 (a type of fungicide)

[0033] 1. Isolation and purification of rhizosphere actinomycetes

[0034] Rhizosphere soil samples from Ningqi No. 1 wolfberry trees were collected in 2021. Trees were over 20 years old. The collection location was at 37°32′21′′N, 105°40′27′′E. The root circumference of the sample tree was 30 cm, and the ground diameter was 9.55 cm. After digging up the entire plant, the soil on the roots was shaken off. Healthy rhizosphere soil was carefully brushed onto sterile newspaper using a sterile brush and collected as rhizosphere soil. This was stored at low temperature and used as soon as possible for the isolation of rhizosphere actinomycetes. The collected rhizosphere soil was passed through a 20-mesh sieve, and 10 g was weighed and placed in 90 mL of sterile water to prepare a bacterial suspension. The suspension was placed in a constant temperature shaker at 150 r / min for 2 hours and then allowed to stand for 1 hour. The supernatant was then used to dilute the suspension to five different concentrations using a gradient dilution method. 100 μL of each dilution was plated onto agar plates, with three replicates per gradient, and incubated at 28°C for 3 days. Observe the growth of colonies on the plates. Single colonies with different morphology, color, and transparency are numbered and then picked separately and purified on new WL-50 medium plates. This process is repeated at least 5 times until a pure culture is obtained. The purified actinomycete single colonies are then incubated in TSB liquid medium at 150 r / min for 3 days and stored at -20℃ with 60% glycerol at a 1:1 ratio.

[0035] Figure 1 The colony morphology of strain NA05 on different culture media is shown. NA05 has an earthy smell, the colonies are opaque and dry, and the colonies are bright in color on different culture media.

[0036] 2. Classification and identification of actinomycete NA05

[0037] The activated strain NA05 was used to conduct physiological and biochemical tests on nitrate reducing ability, starch hydrolysis, peroxidase production, gelatin liquefaction, melanin production, H2S production, tryptophan decomposition, and cellulose decomposition. The taxonomic position of NA05 was determined based on these physiological and biochemical characteristics. The activated actinomycetes were inoculated into TSB liquid medium and cultured at 28℃ and 150 rpm for 3 days. Total DNA was extracted using a bacterial genomic DNA extraction kit. Using the genomic DNA as a template, PCR amplification of multiple gene fragments, including 16S rRNA, gyrB, and trpB, was performed. The PCR reaction system (50 μL) consisted of: 25 μL Taq PCR Master Mix solution, 2 μL each of forward and reverse primers, 2 μL template, and ddH2O added to a final volume of 50 μL. The gene amplification program was: 94℃ pre-denaturation for 4 min, 94℃ denaturation for 40 s, 55℃ annealing for 45 s, 72℃ extension for 1 min, for a total of 30 cycles, followed by a final extension at 72℃ for 8 min, and storage at 4℃. PCR products were separated using 1% agarose gels at 100V, and a gel imaging system was used to check for amplification success. Successfully amplified PCR products were sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing. The obtained sequences were analyzed and compared using the BLAST tool in GenBank. Highly similar sequences were downloaded as reference sequences, and a phylogenetic tree was constructed using the NJ method in Mega 5.0. Based on colony morphology, the physiological and biochemical characteristics of the strain, and the phylogenetic tree constructed for strain NA05, it was finally identified as… S. flavofungini .

[0038] Table 1. Physiological and biochemical indicators of strain NA05

[0039]

[0040] Figure 2 Phylogenetic trees were constructed based on multiple gene sequences of 16S rRNA, atpD, recA, gyrB, rpoB, and trpB, respectively. Figure 2 The results in Table 1 show that the antagonistic bacterium NA05 was taxonomically classified based on physiological and biochemical indicators combined with multi-gene fragment identification. S. flavofungini That is, streptomycin.

[0041] Example 2: Inhibitory effect of Streptomyces NA05 (a fungicide) on root rot pathogens

[0042] 1. Materials and Methods

[0043] 1.1 Experimental Materials

[0044] The following root rot pathogens, isolated and identified by our laboratory from rotten roots of wolfberry, are: Fusarium solani H203, Fusarium rosenbergii H103, Fusarium moniliforme H101, Fusarium rosenbergii QT205, Fusarium floridum QT114, Fusarium oxysporum QX206, Rhizoctonia solani QX106, and Fusarium solani QT205.

[0045] 1.2 Culture medium

[0046] PDA medium: Peeled potatoes 200g / L, boil for 20-30 minutes, filter the clear liquid through gauze, add glucose 20g / L to the clear liquid, make up to volume and dispense, agar 20g / L (dispensed in advance), sterilize in an autoclave at 115℃ for 30 minutes.

[0047] WL-50 medium: yeast extract 1g / L, soluble starch 5g / L, sodium chloride 2.5g / L, magnesium sulfate 3.6g / L, L-alanine 0.2g / L, L-arginine 0.2g / L, L-asparagine 0.5g / L, magnesium chloride 4.8g / L, agar powder 20g / L, sterilized in an autoclave at 115℃ for 30min.

[0048] TSB medium: 5 g / L yeast extract, 15 g / L tryptone, 5 g / L soybean peptone, 5 g / L sodium chloride, sterilized in an autoclave at 121°C for 20 min.

[0049] 2. Experimental Methods

[0050] 2.1 Determination of antibacterial activity of strain NA05

[0051] The root rot pathogen was activated and cultured on PDA plates, and mycelial cakes were created using an 8mm diameter punch. The mycelial cakes were inoculated into the center of a WL-50 plate, with NA05 bacteria symmetrically inoculated on both sides 1cm away from the cake. The control group was inoculated only with the pathogen. Each treatment was repeated in triplicate and incubated at 28℃. When the mycelium of the control group covered the plate completely, the diameter was observed and measured. The inhibition rate of each strain was calculated using a formula, and the average value was used for comparison and evaluation.

[0052] Inhibition rate (%) = (Control group diameter - Treatment group diameter) / (Control group diameter - Mycelium cake diameter) × 100%

[0053] 2.2 Determination of the growth inhibition of pathogenic fungal mycelia by fermentation broth of strain NA05

[0054] NA05 was inoculated into TSB medium and cultured at 28℃ and 150 rpm for 7 days. The fermentation broth was centrifuged at 8000 rpm for 5 min, and the supernatant was filtered through a 0.22 μm microporous membrane in a clean bench to obtain sterile fermentation filtrate. The sterile filtrate was mixed with 2×PDA (sterilized and cooled to 50-60℃) at a 1:1 ratio, and approximately 20 mL was poured into each petri dish to obtain sterile fermentation filtrate plates. These plates were then dried with steam and used as treatment group 1. Plates prepared by adding an equal volume of fermentation broth sterilized at 121℃ for 30 min were designated as treatment group 2. Plates prepared by mixing 2×PDA and ordinary TSB at a 1:1 ratio served as the control group. The tested pathogenic fungus was inoculated at the center of each culture medium plate. Each sample was repeated three times and incubated at 28 ℃. Measurements were taken on the 3rd and 5th days. The colony diameter was measured using the cross-sectional method. The inhibition rate of each fermentation broth against the pathogenic mycelium was calculated according to the formula.

[0055] Mycelial inhibition rate (%) = (Control group diameter - Treatment group diameter) / (Control group diameter - Mycelial cake diameter) × 100%

[0056] 3. Experimental Results

[0057] 3.1 Inhibitory effect of strain NA05 on pathogens

[0058] In the plate confrontation experiment, strain NA05 showed significant inhibitory effects on the growth of all seven pathogens causing root rot in wolfberry. Strain NA05 exhibited the strongest inhibitory effect against *Rhizoctonia solani*, with an inhibition rate as high as 89.9%; its inhibitory effect on *Fusarium solani* was relatively weak.

[0059] 3.2 Inhibitory effect of fermentation broth of strain NA05 on mycelial growth of pathogenic fungi

[0060] Table 2. Antibacterial rate of fermentation broth after different treatments (5 days)

[0061]

[0062] Table 2 shows that under both filtration sterilization and high-temperature sterilization treatments, the inhibition rate of the high-temperature sterilized filtrate against different pathogens was slightly lower than that of the filtration sterilized filtrate. Among them, the fermentation broth of strain NA05 showed the best inhibitory effect against Rhizoctonia solani QX106, with inhibition rates all above 70%; the lowest inhibition rate was against Fusarium solani, approximately 30%; and the inhibitory effects against other fungi were also significant. Furthermore, the antibacterial effects against pathogens were almost identical under both treatments, indicating the presence of extracellular antibacterial substances targeting the pathogens of Lycium barbarum root rot, and suggesting that some of these antibacterial substances possess a certain degree of temperature stability.

[0063] Strain NA05 exhibits significant inhibitory effects against various root rot pathogens, including Rhizoctonia solani QX106, Fusarium oxysporum QX206, Fusarium arvense QT114, Fusarium solani H203, Fusarium rosenbergii H103, Fusarium moniliforme H101, and Fusarium oxysporum QT205, with inhibition rates all exceeding 60%. Figure 3 A); its 7-day fermentation broth, after high-temperature sterilization and aseptic filtration, showed a significant inhibitory effect on the growth of pathogenic fungal hyphae, with an inhibition rate reaching up to 74.8% ( Figure 3 B).

[0064] Example 3: The effect of Streptomyces flavonoids NA05 on the prevention and control of root rot in wolfberry and its microecological regulation.

[0065] 1. Materials and Methods

[0066] 1.1 Study on the control of root rot disease of wolfberry by strain NA05

[0067] Two-year-old bare-root seedlings of Ningqi No. 5 wolfberry were transplanted into 25cm diameter pots at room temperature using sterilized mixed soil (sand: nutrient soil: coconut coir = 1:1:1) and managed until the plants were stable. Single colonies of strain NA05 were inoculated into 100mL TSB shake flasks and incubated at 28℃ and 150r / min for 4 days. 100mL of NA05 bacterial suspension was inoculated using the root drenching method, while the control group was inoculated with 100mL TSB. Ten days later, the treatment groups were simultaneously inoculated with 100mL of Fusarium oxysporum QX206 and 100mL of NA05 bacterial suspension, while the control group was inoculated with 100mL of Fusarium oxysporum QX206 bacterial suspension and 100mL TSB medium. Five replicates were performed for each group. Plant changes were observed and recorded on days 5 and 15 after pathogen inoculation.

[0068] 1.2 Study on the regulation of rhizosphere microecology by strain NA05 of Lycium barbarum

[0069] Fifteen days after inoculation, the wolfberry plants were carefully removed, exposing their roots. Rhizosphere soil and root tissue samples were collected from two groups of wolfberry plants. Approximately 30g of rhizosphere soil was collected from each of three plants within the same treatment group, sealed, labeled, and stored at low temperature for rhizosphere microbial community structure analysis. These samples were labeled GJ-CK and GJ-NA05, respectively. Root tissue samples were incubated twice in sterile phosphate buffer solution at 4°C and 180 rpm for 20 min. The washings were collected separately and combined. The samples were centrifuged at 10000 rpm for 10 min at low temperature, and the precipitate was collected as root surface samples, labeled GB-CK and GB-NA05, respectively.

[0070] 2. Experimental Results

[0071] 2.1 Control effect of strain NA05 on root rot

[0072] Compared with the control group that was only inoculated with pathogens, the symptoms of root rot in wolfberry were significantly reduced or even disappeared after inoculation with bacterial suspension of strain NA05, indicating that strain NA05 has a significant control effect on root rot in wolfberry. Figure 4 ).

[0073] 2.2 Regulatory effect of strain NA05 on the microecology of Lycium barbarum

[0074] Table 3. Diversity index of rhizosphere and root surface fungi

[0075]

[0076] Table 4. α-diversity index of rhizosphere and root surface bacteria

[0077]

[0078] Note: All data are mean ± standard deviation. Different letters indicate significant differences (p < 0.05).

[0079] The results in Tables 3 and 4 show that, compared with GJ-NA05 and GB-NA05, after inoculation with strain NA05, the diversity indices of fungi in the rhizosphere and root surface of wolfberry plants (Chao, Shannon, ACE, Simpson, and Sobs) were significantly higher than those in the control group. In terms of community structure, the relative abundance of beneficial fungi (Morodermae) increased significantly, while the relative abundance of pathogenic fungi (Fusarium) decreased significantly. In terms of bacterial community composition, the relative abundance of antagonistic microorganisms such as Pseudomonas and Bacillus increased. This indicates that strain NA05 can effectively resist the occurrence of wolfberry root rot caused by Fusarium and can recruit more beneficial microorganisms to maintain a healthy microecological environment in the rhizosphere of wolfberry. Figure 5 and Figure 6 The composition and relative abundance of root surface and rhizosphere fungi and bacteria at the phylum and genus levels were determined. The antagonistic bacterium NA05, when inoculated into the soil of wolfberry potted plants, can regulate the rhizosphere microecology of wolfberry and resist the occurrence of root rot disease.

[0080] In summary, the strain NA05 obtained in this study ( S. flavofungini Streptomyces NA05 exhibits significant inhibitory effects against various pathogens causing root rot. Both sterile and high-temperature sterilized filtrates of strain NA05 inhibit the growth of mycelia of various pathogenic fungi, with a maximum inhibition efficiency of 70%. Pot experiments verified the effectiveness of strain NA05 against wolfberry root rot, and inoculation with strain NA05 regulated the community diversity of rhizosphere bacteria and fungi in wolfberry. Streptomyces NA05 combats wolfberry root rot not only by secreting extracellular antibacterial substances but also by adjusting the community structure of soil microorganisms.

[0081] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A biocontrol actinomycete for preventing and controlling root rot in wolfberry, characterized in that, The biocontrol actinomycete for controlling wolfberry root rot is *Streptomyces flavovirens* (a type of fungus). S. flavofungini NA05, accession number CGMCC No. 29739, accession date January 23, 2024, accession address China General Microbiological Culture Collection Center.

2. The biocontrol actinomycete as described in claim 1, characterized in that, The Streptomyces NA05 strain has an earthy odor, opaque colonies, and a dry colony surface.

3. The biocontrol actinomycete as described in claim 1, characterized in that, The genome size of the *Streptomyces flavomycin* NA05 is 9548746 bp, and the GC content is 72.12%, making it a high-GC microorganism.

4. The application of the biocontrol actinomycetes for controlling wolfberry root rot as described in any one of claims 1 to 3 in the control of wolfberry root rot, characterized in that, The Streptomyces NA05 strain containing flavomycin has a significant inhibitory effect on the pathogenic fungus causing root rot in wolfberry.

5. The application as described in claim 4, characterized in that, The pathogenic fungi causing root rot in wolfberry include Rhizoctonia solani, Fusarium oxysporum, Fusarium floridum, Fusarium solani, Fusarium rosenbergii, Fusarium moniliforme, Fusarium moniliforme, and Fusarium rosenbergii.

6. The application as described in claim 4, characterized in that, The conidia of Streptomyces NA05, which is described as a yellow-resistant fungus, are used directly or processed into preparations for the prevention and control of root rot in wolfberry.

7. The application as described in claim 6, characterized in that, The preparations include liquid bacterial agents, powders, and granules.

8. The application of the biocontrol actinomycetes for controlling root rot of wolfberry as described in any one of claims 1 to 3 in regulating the structure and diversity of the rhizosphere microbial community of wolfberry, characterized in that, Applying the aforementioned Streptomyces NA05 to diseased wolfberry soil significantly reduced the abundance of pathogens causing wolfberry root rot and significantly increased the abundance of beneficial bacteria.

9. The application of the biocontrol actinomycetes for controlling root rot of wolfberry as described in any one of claims 1 to 3 in regulating the structure and diversity of the rhizosphere microbial community of wolfberry, characterized in that, The yellow-antimycin-resistant Streptomyces NA05 was used to induce systemic resistance in wolfberry.

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