CN114214231B

CN114214231B - Rice endophytic Streptomyces griseus Ahn75 and application thereof

Info

Publication number: CN114214231B
Application number: CN202111531866.1A
Authority: CN
Inventors: 付祖姣; 郭照辉; 胡展; 杨华; 肖蓉; 罗容珺; 程伟; 张敏; 单世平; 魏小武
Original assignee: HUNAN PROVINCE MICROBIOLOGY INSTITUTE
Current assignee: HUNAN PROVINCE MICROBIOLOGY INSTITUTE
Priority date: 2021-12-15
Filing date: 2021-12-15
Publication date: 2023-07-07
Anticipated expiration: 2041-12-15
Also published as: CN114214231A

Abstract

The invention discloses a rice endophytic Streptomyces griseus Ahn75 and application thereof. The strain classification was named: streptomyces griseobrown (Streptomyces griseobrunneus), accession number: cctccc No. M2019890. The Streptomyces griseus Ahn75 can effectively inhibit the growth of 12 different physiological small rice blast pathogens in vitro. The fermentation filtrate of the strain can inhibit hypha growth and spore germination of Pyricularia oryzae simultaneously, contains a plurality of active compounds, wherein the size of the active compounds is distributed below 3kD and 10kD-30kD, and the small molecular active compounds contain valinomycin. Meanwhile, the strain has the growth promoting performances of producing siderophores, decomposing potassium, fixing nitrogen and the like. These results show that the strain has the potential of developing a novel rice pesticide fertilizer with broad spectrum and environmental protection.

Description

Rice endophytic Streptomyces griseus Ahn75 and application thereof

Technical Field

The invention belongs to the field of microorganisms, and relates to a strain of rice endophytic Streptomyces griseus and application thereof in the aspects of resisting rice blast, promoting rice growth and the like.

Background

The rice blast is caused by the infection of fungus Pyricularia oryzae (Magnaporthe oryzae), and is one of the most serious rice diseases in rice areas around the world. The rice blast only needs about 20 days from infection, forming disease spots to diffusing new spores, can infect most tissues of rice, and occurs in a global rice planting area. The loss of rice yield caused by rice blast is about 10% -30% of the total yield each year, and can keep up to six tens of millions of people alive. At present, the breeding of new disease-resistant varieties and the spraying of chemical pesticides are main means for preventing and treating rice blast, but the breeding of the new disease-resistant varieties has the problems of long period and easy loss of resistance, and a large amount of chemical pesticides not only pollute the environment, but also cause harmful substances to remain in rice to influence human health. Therefore, the search for new methods for controlling rice blast is becoming more and more important, and biological control is an important research area.

Endophytes are microbial flora that can stably colonize the interior of a plant throughout the whole or part of the plant's growth cycle. In contrast to rhizosphere and soil microorganisms, endophytes grow inside plants without competing for survival with soil bacteria. Moreover, endophytes survive in plants without significant adverse effects on host plants, forming a reciprocal relationship with the plants during long-term co-evolution. Recent studies have shown that rice plants themselves also have endophytes that inhibit Pyricularia oryzae. As one of the components of the largest production group of antibiotics at present, endophytic streptomyces has obviously better biological control potential.

Disclosure of Invention

The primary aim of the invention is to provide the endophytic streptomycete for preventing and treating rice blast, the strain can effectively inhibit 12 kinds of rice blast germs with different physiological species, and the fermentation liquor has various antibacterial active compounds with different sizes. The strain belongs to plant endophytes and is obtained by screening non-diseased rice stem tissues in a rice blast disease area of Hainan rice.

The strain obtained by the invention is identified as Streptomyces griseus (Streptomyces griseobrunneus) Ahn75 by combining colony-fungus morphological characteristics and phylogenetic tree based on 16S rRNA, gyrB, atpD, recA, rpoB and trpB gene sequences. The strain is preserved by China center for type culture Collection (preservation address: university of Wuhan) at 11 and 4 days of 2019, and the preservation number is CCTCC NO: M2019890.

The second purpose of the invention is to provide the application of the endophytic streptomyces griseus Ahn75 in preventing and controlling rice blast.

The third purpose of the invention is to provide the application of the endophytic Streptomyces griseus Ahn75 fermentation liquor in preventing and controlling rice blast.

Further, the fermentation broth inhibits hypha growth and/or spore germination of Pyricularia oryzae.

The strain obtained by the invention can efficiently inhibit 12 different physiological race rice blast pathogenic bacteria, and the bacteriostasis rate of the strain on rice blast pathogenic bacteria No. 42 is up to 61.93%.

Further studies found that: the biomass and the antibacterial activity of fermentation liquor of the endophytic streptomyces griseus Ahn75 in the ISP2 culture medium with the initial pH value of 7-9 are higher than those of the initial pH value of 4-6. The highest biomass is 1190.63mg/50mL, and the highest antibacterial rate of 100 mu L of fermentation liquor on the growth of pyriform hypha is 72.83%.

The rice endophytic streptomyces griseus Ahn75 fermentation liquor has stable activity below 50 ℃, gradually reduces the activity after being treated above 80 ℃ and is stable to proteinase K.

The fourth purpose of the invention is to provide the application of the active substances in the fermentation liquor of the endophytic streptomyces griseus Ahn75 in preventing and treating rice blast.

Further, the size of the active substances in the rice endophytic streptomyces griseus Ahn75 fermentation liquid is distributed below 3kD and 10kD-30kD,30kD is above, and the active substances below 3kD contain valinomycin.

The inhibition rate of valinomycin to rice blast hypha reaches 52.27% at the concentration of 15 mug/mL.

The fifth object of the invention is to provide the application of the endophytic streptomyces griseus Ahn75 in promoting the growth of rice.

Further, the rice endophytic Streptomyces griseus Ahn75 has at least one of functions of siderophores, potassium decomposition and nitrogen fixation.

The strain obtained by the invention can stably colonize in rice root, stem and leaf tissues, can effectively inhibit the growth of rice blast germ, can fix nitrogen, remove potassium and produce siderophores, and has good development and application prospects.

Drawings

Fig. 1: colony and strain morphology of strain Ahn 75;

fig. 2: strain Ahn75 was based on phylogenetic tree of 5 housekeeping genes such as 16S rRNA and gyrB;

a is 16S rRNA; b5 gene;

fig. 3: growth of strain Ahn75 in ISP2 medium at different pH values;

fig. 4: inhibition of pyriform hypha growth and spore germination by the strain Ahn75 fermentation broth;

A. the growth state of hyphae on a plate containing fermentation filtrate with different concentrations; B. the inhibition level of fermentation filtrate on the growth of pyriform rice hyphae; C. the inhibiting level of fermentation filtrate on the germination of pyriform spores.

Fig. 5: stability of strain Ahn75 fermentation broth to temperature and proteinase K;

a, heat treatment; and B, proteinase K treatment.

Fig. 6: mass spectrum identification of valinomycin in the strain Ahn75 fermentation broth;

fig. 7: colonization analysis of the strain Ahn75 in rice root, stem and leaf tissues.

A. Control rice roots stained with trypan blue and rice roots sprayed with Ahn 75-GFP;

colonization amount of Ahn75 in different tissues of rice.

The specific embodiment is as follows:

the invention will be further illustrated with reference to the following examples without limiting the invention.

Example 1 screening and purification of Ahn75 Strain

Collecting mild and non-diseased rice tissues from Hainan three-city rice fields, cleaning, surface sterilizing, cutting stems into small sections with the length of about 1cm, placing in TWYE culture medium, culturing at 37 ℃, separating endophytic actinomycetes from the tissues, picking out the endophytic actinomycetes, transferring the endophytic actinomycetes to 1/2PDA culture medium, streaking, separating and purifying to obtain a pure culture of the actinomycetes. The purified strain was stored in 25% glycerol suspension in a-80℃refrigerator.

Inoculating fresh cakes of different physiological small species of Pyricularia oryzae at the center of ISP2 culture medium with diameter of 90mm, inoculating actinomycete strain with sterile toothpick at a position 3cm away from the center of the cakes, repeating the treatment of the aseptic strain as control for 3 times, culturing at constant temperature of 28deg.C for 7d, measuring the radius of pathogenic bacteria colony, and calculating antibacterial rate. Antibacterial ratio (%) = (control group colony radius-treatment group colony radius)/(control group colony radius-cake radius) ×100.

TWYE medium composition used: yeast extract 0.25g, dipotassium hydrogen phosphate 0.5g, agar powder 18g, pure water 1000mL, pH 7.2+ -0.2, and sterilizing at 121deg.C under high temperature and high pressure for 25min. After the medium was cooled to about 55℃and the final concentration of benomyl at 50. Mu.g/mL and nalidixic acid at 25. Mu.g/mL were added under aseptic conditions, the mixture was thoroughly mixed and poured into a plate. 1/2PDA medium composition: 100g of potato, 10g of glucose, 18g of agar, 1000mL of water, and sterilizing at high temperature and high pressure for 25min at 121 ℃. ISP2 medium used consisted of: malt extract 10g, yeast extract 4g, glucose 4g, pH 7.2, water 1000mL, and high temperature and high pressure sterilization at 115℃for 30min.

Example 2 identification of Ahn75 Strain

1. Strain morphology observation: the strain is cultured on ISP2 culture medium, the initial colony is round, the gas silk is yellow-white, early spores are grey green, the later spores are earthy yellow, the basal silk is light yellow brown, and the reddish brown pigment is produced in a long time. Taking strains cultured on an ISP2 culture medium in an inserting mode, observing under a phase contrast microscope, wherein spore filaments are straight or wave curved, conidium is spherical to elliptic, and the surface of the conidium is smooth. The early and late colony morphology and the mycelium and spore morphology of the Ahn75 strain are shown in FIG. 1.

2. Identification of strains:

the genome DNA of actinomycetes Ahn75 was extracted using Shanghai bioengineering Co.Ltd bacteria total DNA extraction kit, and the 16s rRNA sequence of Ahn75 strain was amplified using the same as a template and 27F/765R and 704F/1492R as primers (primer sequences shown in Table 1), respectively, while the conserved sequences of gyrB, atpD, recA, rpoB and trpB genes of Ahn75 strain were obtained by PCR amplification (primer sequences shown in Table 1), and sequenced. The 5 conserved gene sequences were ligated end to form a sequence based on which a phylogenetic tree was constructed using the software cultal W2 and mega7.0 using the Neighbor-Joining method (NJ) (fig. 2). The 16s rRNA-based evolutionary tree showed that the Ahn75 strain had the highest homology to Streptomyces griseus (S.griseobrunneneus) standard strain ATCC 4.1838, which was 99.48%. The evolutionary tree of the 5 gene shows that Ahn75 belongs to the same species as Streptomyces griseus ATCC 4.1838 and Streptomyces baculous (S.bacillariis) CGMCC 4.1584. Studies have shown that Streptomyces griseofuscus and Streptomyces baculous are the same species. The strain is preserved in China center for type culture Collection (China) with the preservation number of 11 months 4 in 2019: CCTCC No. M2019890, accession number address: chinese, university of martial arts, martial arts.

TABLE 1 primer sequences required for PCR amplification

EXAMPLE 3 bacterial Strain bacteriostasis against physiological races of different Pyricularia oryzae

The antibacterial activity of the Ahn75 strain against physiological races of various rice blast sources was examined by a plate-facing test (the procedure is the same as in example 1), and the results are shown in Table 2.Ahn75 shows higher antibacterial activity on 40 rice blast pathogens of different physiological micro-species, and the antibacterial rate on 10 rice pyriella strains exceeds 50%.

TABLE 2Ahn75 inhibitory Activity against Pyricularia oryzae mycelium growth in different physiological ethnic groups

Example 4 growth Properties of strains under different pH conditions

Inoculating Ahn75 strain into ISP2 solid culture medium, culturing for 3-5 days to obtain spore powder, and suspending in 0.5% Tween aqueous solution to obtain 1×10 strain ⁸ The CFU/mL spore suspension was inoculated into ISP2 medium at pH4-9 at an inoculum size of 2%, each pH was repeated 3 times, 28℃and incubated at 180rpm for 7 days. Collecting fermentation liquor, centrifuging at 10000rpm for 10min, precipitating on an ultra-clean workbench to dry water, weighing and measuring biomass, filtering supernatant with a 0.22 μm sterile microporous filter membrane, adding 100 μl sterile filtrate into oxford cup at 2.5cm from center of Pyricularia oryzae cake on ISP2 solid medium, and performing antibacterial test. The bacteriostasis rate was calculated according to the formula of example 1, and the result is shown in fig. 3.Ahn75 can not grow under the acidic condition of pH4-5, can slowly grow in the culture medium of pH6, has lower antibacterial activity, can quickly grow under the condition of pH7-9, has the maximum biomass obtained under the condition of pH9, and has the highest fermentation broth activity under the condition of pH 8. However, the biomass and the antibacterial activity of the strain under the condition of pH7-9 are analyzed by SPSS19.0 single factor Duncan (D), and no significant difference exists.

Example 5 Activity and stability of Strain fermentation broth

Effect of sterile fermentation filtrate of Ahn75 Strain on Pyricularia oryzae hypha growth

Ahn75 was cultured in ISP2 medium at pH7 as in example 4, and after 7 days, the fermentation filtrate was collected. Diluting the sterile fermentation liquid for 2 times, 4 times, 10 times, 50 times and 100 times, respectively taking 1mL of stock solution and the diluted liquid with different concentrations, respectively, mixing with 9mL of ISP2 culture liquid cooled to 50 ℃, preparing culture medium plates containing 10% of the sterile fermentation liquid, 5% of the sterile fermentation liquid, 2% of the sterile fermentation liquid, 1% of the sterile fermentation liquid and 0% of the sterile fermentation liquid, inoculating fresh bacterial cakes of rice blast in the center of each plate, repeating each treatment for 3 times, taking sterile water as a control, culturing for 7d at a constant temperature of 28 ℃, measuring the colony diameter of pathogenic bacteria by a crisscross method, and calculating the growth inhibition rate of hyphae (bacteriostasis rate (%) = (colony diameter of control group-colony diameter of treatment group)/(colony diameter of control group-bacterial cake diameter) ×100). The Ahn75 strain fermentation liquor shows concentration dependency on the inhibition of pyriform hyphae, and when the concentration of the Ahn75 strain fermentation liquor is increased from 1% to 10%, the bacteriostasis rate of the Ahn75 strain fermentation liquor is increased from 25.05+/-0.22% to 80.88 +/-1.54%, and the results are shown in figures 4A and 4B.

Effect of sterile fermentation filtrate of Ahn75 Strain on Pyricularia oryzae spore germination

Preparation of rice blast spore suspension: washing out spores of Pyricularia oryzae preserved on sorghum grains with sterile water, coating 100 mu L of spores on a fresh ISP2 plate, culturing for 3d at 28 ℃, picking single colony, inoculating to another fresh ISP2 plate, culturing for 6d at 28 ℃, picking hyphae, inoculating to oat culture medium (30 g of oatmeal is boiled with pure water for 1h, filtering with four layers of gauze to remove sediment, adding 100mL of squeezed fresh tomato juice, 15g of agar powder, setting the volume of pure water to 1000mL, pH 7.2 and 121 ℃ for 20 min), brushing off aerial hyphae with a brush after hyphae on the plate are full (about 7-10 d), and culturing the plate in a 28 ℃ artificial climate incubator alternately (14:10 h). After the spores are fully produced (about 3-4 d), each dish is washed by 5mL of sterile water, and the spores are filtered by sterilized mirror wiping paper to prepare 10 ⁵ individual/mL suspension of Pyricularia oryzae spores.

Sterile fermentation broth of Ahn75 was proportioned to a suspension of Magnaporthe grisea spores in a 1.5mL Ep tube (10 ⁵ And (3) mixing with sterile water to prepare sterile fermentation liquid with concentration of 5%, 10%, 20% and 50%, repeating each treatment for 5 times, setting sterile water and pyriform spores suspension to be mixed as a control, standing and culturing for 16 hours in a 28 ℃ incubator, detecting spore germination condition under a 10×20 lens by using a microscope, counting the spore germination rate of each treatment, and calculating the spore germination inhibition rate according to the following formula, wherein the result is shown in fig. 4C. The results showed that when the concentration of the Ahn75 filtrate was 50%, the spore germination inhibition rate was 79.15% + -7.18%.

Spore germination inhibition (%) = (control spore germination rate-treated spore germination rate)/control spore germination rate×100

Stability of the sterile fermentation filtrate of the Ahn75 Strain to temperature and protease

Treating Ahn75 sterile fermentation filtrate at different temperatures for 30min respectively, simultaneously adding proteinase K into the subpackaged Ahn75 sterile fermentation filtrate, treating at 50 ℃ for 30-120min respectively, and detecting the inhibition activity of the obtained treatment liquid on pyriform hypha growth according to the above method respectively, wherein the result shows that the activity of the Ahn75 fermentation filtrate is basically unchanged from that of the untreated filtrate after the treatment at 40 ℃ and 50 ℃ for 30min, the antibacterial activity of the fermentation filtrate is gradually reduced along with the increase of the treatment temperature, and the antibacterial activity is basically completely lost after the treatment at 121 ℃ for 30min, which indicates that active substances generated by the strain are unstable at a high temperature of more than 80 ℃ and stable at a temperature of less than 50 ℃ (figure 5A). After the Ahn75 fermentation broth is treated by proteinase K for 30-120min respectively, the antibacterial activity is still between 93.99% and 105.35%, and the antibacterial activity is not significantly different from that of a control (figure 5B).

EXAMPLE 6 analysis and identification of antimicrobial active ingredients in fermentation broths of Ahn75 Strain

1. Size analysis of active Compounds

The Ahn75 fermentation filtrate was ultrafiltered by using 3kD, 10kD and 30kD ultrafilters, and the ultrafilter filtrate and supernatant were collected, and the antibacterial activity of the treatment fluid on the growth of Pyricularia oryzae mycelia was examined as in example 4, and the results are shown in Table 3, the antibacterial activity of Ahn75 synthesized was mainly concentrated to more than 3kD, the antibacterial activity of the compound was 6.5 times that of the compound below 3kD, the sizes were distributed in 3-10kD,10-30kD and above 30kD, and the filtrate below 3kD also showed a antibacterial rate of 7.45%, indicating that the strain also synthesized antibacterial compounds having a molecular weight less than 3 kD.

TABLE 3 bacteriostatic Activity of fermentation filtrate of Ahn75 Strain after treatment with ultrafiltration Membrane

2. Identification of active Compounds

The aseptic Ahn75 fermentation filtrate is extracted by adopting n-butanol in an equal volume, the organic phase is subjected to rotary evaporation, and the obtained antibacterial crude extract is re-dissolved by using aseptic ultrapure water and is analyzed by a liquid-mass coupling mass spectrometer (Agilent Poroshell HILIC-Z connection Thermo LTQ Orbitrap XL mass spectrometer). The obtained secondary mass spectra were aligned in the GNPS: global Natural Product database (http:// GNPS. Ucsd. Edu). The results show that the mass of M/z 1149.59, 1133.63 matches the mass-to-charge ratio of [ M+K ] +, [ M+Na ] + of Valinomycin (Valinomycin) in database NIST14, and that the MS2 profile of both precursor ions also matches the secondary mass profile of Valinomycin (FIG. 6). Valinomycin has a molecular weight of about 1kD, and by analyzing the inhibitory activity of the standard valinomycin purchased on Pyricularia oryzae mycelia (the method is performed as in example 5), it was found that valinomycin does have inhibitory activity on Pyricularia oryzae. From this, it is assumed that the Ahn75 strain synthesizes valinomycin which is active against rice blast.

Analysis of secondary metabolite biosynthesis Gene Cluster in Ahn75 Strain genome

Genomic DNA of the Ahn75 strain was extracted as in example 2, the genomic DNA was fragmented, an Illumina PE library (400 bp library) was constructed, illumina Hiseq sequencing was performed on the library by bridge PCR, the sequences were cut and spliced by bioinformatic analysis means after quality control of the obtained sequencing data, full genome scan sequences of the strain were obtained, and then the genome sequences were gene predicted and annotated by each big data center. The genome was predicted for the biosynthetic gene cluster of secondary metabolites using anti-map software and found to contain potentially 40 biosynthetic gene clusters of secondary metabolite organisms on the genome of the strain, including 3 lactone-type antibiotics (lactones), 7 non-ribosomal polypeptides (non-ribosomal peptide synthetases, NRPS), 2 similar non-ribosomal polypeptides (NRPS-like), 3 non-ribosomal polypeptide-polyketides (NRPS-PKS), 4 siderophores (siderophores), 8 polyketides (polyketide antibiotics, PKS), 5 terpenoid compounds (terpene), 6 antibacterial peptides and 2 other compounds (Table 4).

TABLE 4 Secondary metabolite biosynthesis Gene Cluster for Strain Ahn75

Example 7 detection of growth-promoting factors and synthetic genes (Gene clusters) of Ahn75

Spore powder of Ahn75 strain was inoculated on Ahn75 strain nitrogen-free solid medium, inorganic phosphorus and organic phosphorus decomposing medium (PKO and Meng Jinna medium), potassium decomposing medium (Yashishan Bao Luofu medium), siderophore chromogenic medium (CAS medium), cultured at 28℃for 7d, colony growth was detected, and diameters of colonies and corresponding hydrolysis circles were measured by the crisscross method, and as a result, ahn75 strain was shown to have nitrogen fixation, potassium decomposition and siderophore production capabilities (Table 5). The genome of the Ahn75 strain was analyzed, and it was found that the strain contained siderophores, nitrogen fixation, trehalose, IAA, arginine, potassium and other genes (clusters) involved in the synthesis of growth factors (Table 6).

TABLE 5 growth factor levels of strain Ahn75

Abbe (Ashby) nitrogen-free solid medium used: glucose 10g, KH ₂ PO ₄ 0.2g，MgSO ₄ ·7H ₂ O 0.2g，CaSO ₄ ·2H ₂ O 0.1g，CaCO ₃ 5g, naCl 0.2g, agar 18.0g, deionized water 1000mL, pH 7.0.

PKO medium: tricalcium phosphate 5.0g, sucrose 10.0g, (NH) ₄ ) ₂ SO ₄ 0.5g yeast powder 0.5g,NaCl 0.2g,MgSO ₄ ·7H ₂ 0.1g of O, 0.2g of KCl, 3.0mL of 1% manganese sulfate, 3.0mL of 1% ferrous sulfate, pH7.0, 18.0g of agar and 1000mL of deionized water.

Meng Jinna medium: glucose 20.0g, (NH) ₄ ) ₂ SO ₄ 0.5g，NaCl 0.3g，KCl 0.3g，MgSO ₄ ·7H ₂ O 0.3g，FeSO ₄ ·7H ₂ O 0.03g，CaCO ₃ 5.0g，MnSO ₄ ·4H ₂ O 0.03g，(NH ₄ ) ₃ PO ₄ 0.5g, 10mL of egg yolk liquid (prepared from sterile normal saline and egg yolk 1:1) is added, the pH is 7.0-7.5, and the deionized water is 1000mL.

Culture medium of yama Bao Luofu: sucrose 5.0g, na ₂ HPO ₄ 2.0g，MgSO ₄ ·7H ₂ O 0.5g，FeCl ₃ 5.0mg，CaCO ₃ 0.1g, 1.0g of potassium feldspar powder, pH of 7.0-7.5, 18.0g of agar and 1000mL of deionized water.

CAS medium: 20% glucose solution 1mL,10% Casein amino acid 3mL,1mmol/L CaCl ₂ 0.1mL，1mmol/L MgSO ₄ 2mL, CAS dye 10mL, phosphate buffer 10mL, agar 1.8g, deionized water 74mL.

Preparation of CAS dye liquor (200 ml): and (3) solution A: 0.12g of Chrome Azure (CAS) is dissolved in 100mL of double distilled water and combined with 1mmol/L FeCl ₃ And mixing 20mL of the solution to obtain 120mL of solution A. And (2) liquid B: cetyl trimethylammonium bromide 0.15g was dissolved in 80mL double distilled water to give solution B. Slowly adding the solution A into the solution B, and fully and uniformly mixing to obtain the CAS dye liquor.

Phosphate buffer: na (Na) ₂ HPO ₄ ·12H ₂ O 2.427g，NaH ₂ PO ₄ ·2H ₂ O 0.590g，KH ₂ PO ₄ 0.075g，NH ₄ Cl 0.250g,NaCl 0.125g, deionized water 100.0mL, pH 6.8.

TABLE 6Ahn75 growth-promoting genes (Cluster) of Strain

Example 8 colonization of Ahn75 in Rice

Ahn75 spore suspension is sprayed on rice in the 3-4 leaf stage, sterile water is sprayed on the control, rice roots are collected and washed after 1-3 days and treated and dyed by trypan blue dyeing method, the colonization condition of endophytes is observed under a phase contrast microscope, actinomycetes can be well grown on the rice roots, and no hyphae grow on the control roots without spraying Ahn75 (figure 7A). Collecting different tissues of rice on days 1-27 after spraying the Ahn75 spore suspension, re-separating and counting the colonized Ahn75 by adopting an endophyte separation method, counting the colonization amount of the Ahn75 in different tissues of the rice at different times, and finding that the colonization amount of the Ahn75 in each tissue of the rice is rapidly increased after being sprayed, and gradually decreasing until the state is gentle along with the time. Wherein the amount of colonization in root tissue is greatest on day 3, whereas the amount of colonization in stems and leaves peaks on day 5. Ahn-75 was more capable of colonization in stem tissue than in roots and leaves, and the amount of colonization was consistently higher from day 5 to day 27 than in roots and leaves (FIG. 7B).

Claims

1. Streptomyces griseus endophytic in riceStreptomyces griseobrunneus) Ahn75 has a preservation number of CCTCC NO: M2019890.

2. The use of the endophytic Streptomyces griseus Ahn75 of claim 1 for controlling rice blast.

3. The use of the endophytic Streptomyces griseus Ahn75 fermentation broth of claim 1 for controlling rice blast.

4. The use according to claim 3, wherein the fermentation broth inhibits hyphal growth and/or spore germination of Pyricularia oryzae.

5. Use of the endophytic Streptomyces griseus Ahn75 of claim 1 for promoting rice growth; the rice endophytic Streptomyces griseus Ahn75 has at least one of functions of producing siderophores, dissolving potassium and fixing nitrogen.