A tea tree root rot antagonistic strain Streptomyces colloidalis JK-13 and its application

Abstract

The invention discloses a tea tree root rot antagonistic strain, Streptomyces gelaticus JK‑13, and an application thereof, and belongs to the technical field of screening antagonistic strains for tea tree root rot. Streptomyces gelaticus JK‑13 was deposited in the China Center for Type Culture Collection on October 16, 2023, with a deposit number of CCTCCNO: M20231912, a deposit address of Wuhan University, Wuhan, China, and a classification name of Streptomyces gelaticus JK‑13. The strain JK‑13 has an inhibition rate of 67.06% on Fusarium cugenangense, a pathogen of tea tree root rot, and exhibits good broad-spectrum antibacterial activity against a variety of plant pathogenic fungi. Therefore, Streptomyces gelaticus JK‑13 can be prepared into a biological preparation to prevent and treat tea tree root rot and a variety of plant pathogens, thereby avoiding the side effects and drug resistance of chemical control.

Description

Technical Field

[0001] The invention relates to the technical field of screening tea tree root rot antagonistic strains, and more specifically to a tea tree root rot antagonistic strain Streptomyces colloidalus JK-13 and an application thereof. Background Art

[0002] Tea is an important economic crop in my country. Tea contains a variety of unique active substances such as tea polyphenols, caffeine, theanine, tea polysaccharides, etc., which have the effects of anti-oxidation, hypoglycemic, anti-cancer, and enhancing immunity. There are many types of tea tree diseases, such as tea anthracnose caused by Colletotrichum camelliae and C. gloeosporioides, tea ring spot caused by Pseudopestal otiopsis theae, and tea stem rot and wilt-related diseases caused by Fusarium solani, which cause great harm to the healthy growth and development of tea trees, thereby affecting the yield and quality of tea.

[0003] Tea root rot is one of the main diseases of tea tree roots. After the pathogen infects tea plants, it can cause the tea trees to grow weak or die, and spread from plant to plant, causing the death of large areas of tea trees, which is very harmful to tea production. In previous studies, we reported a pathogen that causes tea root rot, Fusarium cugenangen se, which belongs to a specific strain of Fusarium oxysporum species complex (FOSC). At present, many biocontrol bacteria have been discovered and studied for root rot caused by Fusarium oxysporum species complex, such as Bacillus spp., Brevibacterium spp., Agrobacterium spp., Pseudomonas spp., and Trichoderma spp., which have good control effects on Fusarium oxysporum species complex, but there are few reports on the exploration and development of antagonistic microbial resources against tea root rot pathogens.

[0004] At present, due to the certain harm of chemical agent control to plants and the surrounding environment, the role of antagonistic microorganisms in the disease control of tea trees, camellia oleifera, flowers and fruit trees is becoming more and more prominent. Antagonistic microorganisms are mainly isolated and screened from the soil or plant endophytes. Antagonistic microorganisms and their metabolites have good control effects on the root diseases of tea trees. For example, Elango et al. (2015) found that in 13 experimental treatments, the combined application of Streptomyces griseus and Gibberella hiemalis to the rhizosphere of tea trees could significantly reduce the incidence of tea red root rot; The research results of Morang et al. (2018) showed that three rhizobial strains, PM105, PM 112 and PM 43, not only inhibited brown rot, but also promoted plant growth. Purkayastha et al. (2018) found that Serratia marcescens could produce a variety of cell wall hydrolases, so as to achieve inhibitory effects by degrading the cell walls of pathogenic bacteria, but there are few relevant research reports on the antagonism of Streptomyces gummosus against tea root rot pathogens.

[0005] Therefore, how to screen a Streptomyces gummosus that antagonizes the pathogenic bacteria of tea root rot is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention screens antagonistic Streptomyces gummosus from the rhizosphere soil of tea trees, identifies the biocontrol bacteria by morphological and molecular biological methods, studies the antibacterial activity of the biocontrol bacteria JK-13 and the antibacterial mechanism of the biocontrol bacteria JK-13 against tea root rot, and explores the optimal culture conditions of the biocontrol bacteria, in order to provide theoretical and technical support for the biological control of tea root rot.

[0007] A Streptomyces gummosus JK-13, an antagonistic strain against tea root rot, was deposited with the China Center for Type Culture Collection on October 16, 2023, with the deposit number CCTCC NO: M20231912, the deposit address being Wuhan University, Wuhan, China, and the taxonomic name being Streptomyces gelaticus JK-13.

[0008] As the same inventive concept as the above technical solution, the present invention also requests to protect the application of the Streptomyces gummosus JK-13 in the preparation of biological agents against Phytophthora cactorum, Colletotrichum sichuanense, Alternaria solani, Fusarium zizaniae, Diaporthe citri, Phomopsis vexans, Fusarium oxysporum f. sp. capsici, Setosphaeria turcica.

[0009] As the same inventive concept as the above technical solution, the present invention also requests to protect the application of the volatile and non-volatile metabolites of the Streptomyces gummosus JK-13 in the preparation of biological agents against the pathogenic bacteria of tea root rot.

[0010] As an inventive concept identical to the above technical solution, the present invention also seeks to protect the use of the fermentation broth of Streptomyces colloidales JK-13 in the preparation of a biological agent for antagonizing tea tree root rot pathogens.

[0011] Preferably, the fermentation broth of Streptomyces colloidalis JK-13 is prepared by culturing Streptomyces colloidalis JK-13 in a culture medium consisting of 10.0 g / L millet, 10.0 g / L maltose, 5.0 g / L ammonium sulfate, 2.5 g / L potassium chloride, and 3.0 g / L calcium carbonate.

[0012] As an inventive concept identical to the above-mentioned technical scheme, the present invention also requests protection for a culture medium for preparing a fermentation broth of Streptomyces colloidus JK-13, wherein the culture medium comprises: 10.0 g / L millet, 10.0 g / L maltose, 5.0 g / L ammonium sulfate, 2.5 g / L potassium chloride, and 3.0 g / L calcium carbonate.

[0013] As the same inventive concept as the above technical solution, the present invention also claims a method for preparing a fermentation broth of Streptomyces colloidus JK-13, the process comprising: using Gao's No. 1 culture broth as a seed culture medium, taking 20 antagonistic strain cakes with a diameter of 5 mm in 200 mL of Gao's No. 1 culture broth, and culturing at 28°C and 180 r / min for 7 days to obtain the seed broth. The seed broth is inoculated into the fermentation medium at a 2% inoculation amount and cultured at 28°C and 180 r / min for 7 days to obtain the fermentation broth of Streptomyces colloidus JK-13.

[0014] It can be known from the above technical scheme that, compared with the prior art, the present invention screened an antagonistic strain JK-13 with good prevention and control effect on root rot from the rhizosphere soil of tea trees. The strain JK-13 was identified based on morphological characteristics observation, physiological and biochemical tests and 16S rRNA sequence analysis, and the strain was determined to be Streptomyces gelaticus. The biological control mechanism of strain JK-13 on tea root rot pathogens was elucidated by confrontation culture, microscopic observation, extracellular enzyme analysis, volatile and non-volatile organic components and sterile fermentation liquid. The results showed that the strain JK-13 had an inhibition rate of 67.06% on the tea root rot pathogen Fusarium cugenangense, and showed good broad-spectrum antibacterial activity against a variety of plant pathogenic fungi. The bacteria inhibited the growth of pathogens by producing volatile and non-volatile organic compounds, metabolites, and extracellular enzymes such as starch hydrolase, cellulose hydrolase, and β-1,3-glucanase with antibacterial activity. The hyphae of pathogens were observed to be branched, constricted, twisted, deformed, and entangled with each other under an optical microscope. The results of the optimization of fermentation culture conditions showed that the most suitable carbon source, nitrogen source, and inorganic salt for growth were maltose, (NH4 ) 2 SO 4 , KCl, the best fermentation medium formula is millet 10.0g / L, maltose 10.0g / L, (NH 4 ) 2 SO 4 5.0 g / L, KCl 2.5 g / L, CaCO 3 3.0g / L. Therefore, Streptomyces colloidinus JK-13 has good development value and application potential in the disease management of tea tree root rot BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0016] Figure 1 The attached figure shows the antagonistic effect of strain JK-13 on pathogenic bacteria F. cugenangense on PDA; A: treatment group; B: control group CK;

[0017] Figure 2 The attached figures show the morphological characteristics of strain JK-13; A and B are the front and back of strain JK-13 on Gao's medium No. 1, respectively; C and D are the results of microscopic observation of strain JK-13;

[0018] Figure 3 The accompanying figure is a phylogenetic tree of strain JK-13 constructed based on 16S rRNA sequence;

[0019] Figure 4 The attached figure shows the inhibitory effect of strain JK-13 on the mycelial growth of tea root rot pathogen; A: control group; B: treatment group

[0020] Figure 5 The attached figures show the extracellular enzyme detection indicators of strain JK-13; A is the determination of starch hydrolase production; B is the determination of cellulose hydrolase production; C is the determination of β-1,3-glucanase activity; D is the determination of protease production;

[0021] Figure 6 The attached figure shows the antibacterial effect of metabolites produced by strain JK-13 on pathogenic bacteria F. cugenangense; a: antibacterial effect of volatile organic compounds on pathogenic bacteria F. cugenangense; b: antibacterial effect of non-volatile organic compounds on pathogenic bacteria F. cugenangense;

[0022] Figure 7 The attached figures show the effects of different culture conditions on the antibacterial activity of the fermentation broth of strain JK-13; a: different culture media; b: different carbon sources; c: different nitrogen sources; d: different inorganic salts. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The test soil in the embodiment was collected from the rhizosphere soil of tea trees infected with root rot pathogens at the Chang'an Teaching Base of Tea Science of Hunan Agricultural University; the plant pathogens tested were tea root rot pathogen (Fusariumcugenangense), strawberry blight pathogen (Phytophtherafragariae), Polygonatum anthracnose pathogen (Colletotrichum spaethianum), potato early blight pathogen (Alternariasolani), pepper wilt pathogen (Fusarium oxysporum), wild rice stem fusarium (Fusariumgraminearum), eggplant brown streak pathogen (Phomopsis vexans), citrus scurf pathogen (Diaporthecitri), and corn leaf blight pathogen (Exserohilum turcicum), all of which were preserved in the laboratory of Hunan Agricultural University.

[0025] Example 1 Isolation and screening of antagonistic strains

[0026] The dilution coating method was used to isolate the colloid Streptomyces strain. Weigh 10 g of the test soil and mix it with 90 mL of sterile water to obtain a concentration of 10 -1 The soil solution was diluted to 10% with sterile water. -4 , 10 -5 , 10 -6 Multiple dilutions were made, and each dilution gradient was repeated 3 times. 200 μL of soil dilution solution was taken and spread on PDA medium, and cultured at 28℃ for 7-14 days. After the colonies grew on the plate, single colonies were picked for purification and preservation. Antagonistic bacteria were screened by plate confrontation method. The pathogens were inoculated into the middle of PDA medium with a 5mm diameter puncher, and different soil isolates were inoculated at an equal distance of 2cm from the center of the plate. The non-inoculated isolates were used as controls, and cultured in a constant temperature incubator at 28℃ for 5-7 days. Each treatment was repeated 3 times. When the control colony grew close to the edge of the dish, its antibacterial rate was calculated according to the following formula.

[0027] Bacterial inhibition rate (%) = (colony diameter of control group - colony diameter of treatment group) / colony diameter of control group × 100. (The same below)

[0028] By isolating Streptomyces colloidinus from the rhizosphere soil of tea trees infected with root rot, several strains with antagonistic effects on tea tree root rot pathogen F. cugenangense were obtained by plate confrontation method, but strain JK-13 had the best effect ( Figure 1 ), with an inhibition rate of 67.06%, which was used in subsequent experiments.

[0029] Example 2 Identification of strain JK-13

[0030] The antagonistic strain JK-13 was streaked onto PDA medium, Gao's medium No. 1, ISP-2 medium, Czapek's medium, glucose yeast extract agar medium, nutrient agar medium, and oatmeal agar medium, and cultured inverted in a constant temperature incubator at 28°C for 7 to 14 days to observe the growth of the strain, basal hyphae, aerial hyphae, colony characteristics, and the production of soluble pigments.

[0031] The strain was streaked on Gao's medium No. 1 by the insert method. After 14 days of culture, the characteristics of basal hyphae, aerial hyphae and spore hyphae of the strain on Gao's medium No. 1 were observed under a microscope.

[0032] According to the methods in "Rapid Identification and Systematic Classification of Streptomyces colloidus" and "Streptomyces Identification Manual", the carbon source utilization test, gelatin liquefaction test, methyl red test, VP test, milk coagulation and peptone test, H 2 S production test, nitrate reduction test, melanin production test. GY liquid medium is used for NaCl tolerance test and pH test of antagonistic Streptomyces colloidus. The NaCl concentration adjustment range of the antagonistic strain salt tolerance test is 0-13%, and the pH adjustment range of the pH test is 1-14. The determination method is to inject the sterile white gun tip with the strain spores into a test tube containing 5 or 10mL GY liquid medium, and culture it in a shaker at 28℃ and 180r / min for 7 days to observe whether the strain grows and the growth conditions under different NaCl concentrations and different pH environments.

[0033] The genomic DNA of the antagonistic strain was extracted using a bacterial genomic DNA extraction kit, and the target fragment was amplified using the 16SrRNA universal primers 27F (5-AGAGTTTGATCMTGGCTCAG-3') and 1492R (5-GGTTA CCTTGTTACGACTT3'). The sequencing was sent for similarity comparison on the NCBI website, and the typical strains with higher similarity were selected to construct a phylogenetic tree using the Neighbor-Joining method using the MEGA11 software.

[0034] Morphological characteristics: strain JK-13 grows well on Gao's medium No. 1, with dense colonies, well-developed aerial hyphae, black basal hyphae, gray-black aerial hyphae, no soluble pigments produced in the early stage, and soluble pigments produced in the later stage, and the color is reddish brown ( Figure 2 When cultured and grown on different media, except for the weak growth on PDA and oatmeal agar media, the antagonistic strain JK-13 grew well on other media. The characteristics of the antagonistic strain JK-13 on different media were different (Table 1).

[0035] Table 1 Culture characteristics of strain JK-13 on different identification media

[0036]

[0037] Note: +++: good growth; ++: moderate growth; +: poor growth

[0038] The results of physiological and biochemical tests showed that the gelatin liquefaction test and nitrate reduction test of strain JK-13 were both positive, and the coagulation and peptone test of milk, H 2 The results of S production, methyl red test, VP test and melanin production test were all negative (Table 2). They could use L-galactose, sucrose, D-fructose, D-glucose, D-xylose and maltose as carbon sources, but could not use L-arabinose, D-mannitol, L-inositol and D-sorbitol as carbon sources. The NaCl tolerance test and pH tolerance test showed that strain JK-13 could grow at 8% NaCl concentration, with a pH tolerance range of 5 to 13. It could grow at pH 13, but the growth was weak.

[0039] Table 2 Physiological and biochemical characteristics of strain JK-13

[0040]

[0041] Note: "+" indicates positive, "-" indicates negative

[0042] Example 3 Molecular phylogenetic analysis

[0043] The 16S rRNA gene of strain JK-13 was obtained by PCR amplification, and the obtained sequence was compared with the NCB I database by BLAST homology. It was found that the strain had a high similarity with the genus Streptomyces. The 16S rRNA gene sequence of the strain with high similarity was selected, and the phylogenetic tree was constructed using MEGA11.0. The results showed that strain JK-13 and Streptomyces gelaticus were in the same branch on the phylogenetic tree, and its accession number in the gene bank was No.MW164963 ( Figure 3). Combined with the morphological characteristics, physiological and biochemical tests, and 16S rRNA gene molecular identification of the strain, this strain was preliminarily identified as Streptomyces gelaticus. The Streptomyces gelaticus JK-13 was deposited in the China Center for Type Culture Collection on October 16, 2023, with a deposit number of CCTCC NO: M20231912, and the deposit address is Wuhan University, Wuhan, China, and the classification name is Streptomyces gelaticus JK-13.

[0044] Example 4 Inhibitory effect of antagonistic strain JK-13 on mycelial growth of tea root rot fungi

[0045] From the microscopic results in the figure, it can be seen that under the antagonism of the antagonistic strain JK-13, the mycelial growth of tea root rot fungi will be inhibited to a certain extent. Compared with the control group, the mycelial growth of tea root rot fungi in the treatment group showed branching, constriction, twisting, deformity, and mutual entanglement, which shows that the strain JK-13 has an inhibitory effect on the mycelial growth of tea root rot fungi ( Figure 4 ).

[0046] Example 5 Determination of antibacterial ability of antagonistic strain JK-13

[0047] The antimicrobial spectrum of the antagonistic strain JK-13 was determined by using eight pathogens, including pepper wilt, wild rice stem fusarium, citrus spathogen, cotton wilt, potato early blight, strawberry blight, corn blight, and eggplant brown streak, as indicator bacteria (stored in the Laboratory of Plant Pathogenic Microorganisms and Rice Diseases of Hunan Agricultural University). The plate confrontation method was used to detect its broad spectrum. A 0.5 cm diameter cake of each tested pathogen was taken with a puncher and placed in the center of the culture dish. The antagonistic bacteria were picked with a sterile inoculation loop and streaked on both sides 2 cm away from the pathogen. Only the pathogens were inoculated as controls. Each treatment was repeated 3 times. After culturing in a 28°C incubator for 7 days, the diameter of the inhibition zone was measured and the inhibition rate was calculated.

[0048] Through the plate confrontation test between the antagonistic strain JK-13 and 8 different plant pathogens, it was found that the antibacterial effect of strain JK-13 on the 8 pathogens was more than 50%, among which the antibacterial effect of strain JK-13 on anthracnose of Polygonatum cyrtonema, brown streak of eggplant, and corn blight was more than 80%. Strain JK-13 can effectively inhibit a variety of pathogens on the plate, as shown in Table 3; the antibacterial effect is relatively broad.

[0049] Table 3 Inhibitory effect of strain JK-13 on 8 plant pathogens

[0050] Test strains Inhibition rate (%) Strawberry blight pathogen 68.54±1.30c Colletotrichum cyrtonema 85.00±1.08a Alternaria blight 69.22±1.22c Fusarium sphaeroides 57.77±0.45d Sharp-skinned fungus 69.22±1.89c Eggplant brown streak pathogen 83.53±1.18ab Fusarium wilt 68.22±0.64c Ussuriensis turcica 81.96±1.36b

[0051] Note: Different lowercase letters after the data in the table indicate significant differences at the P<0.05 level.

[0052] Example 6 Detection of extracellular enzymes of antagonistic bacteria

[0053] Use a hole puncher to take the antagonistic strain with a diameter of 5 mm and place it in the center of the detection culture medium for amylase, cellulase, protease, and β-1,3-glucanase respectively. Set up 3 replicates for each type of extracellular enzyme detection culture medium. All plates are cultured in a constant temperature incubator at 28°C for 5-7 days. The detection of amylase requires the addition of Lugol's iodine solution, and it is necessary to observe whether there is a transparent hydrolysis circle. If there is a transparent circle, the extracellular enzyme is produced.

[0054] By testing the extracellular enzyme production performance of the strain, it can be seen that strain JK-13 produces transparent circles in starch hydrolase medium, sodium carboxymethyl cellulose medium, and β-1,3-glucanase medium, indicating that strain JK-13 has the activity of secreting starch hydrolase, cellulose hydrolase, and β-1,3-glucanase; in addition, it does not secrete protease ( Figure 5 ).

[0055] Example 7 Inhibitory Effects of Volatile and Non-volatile Organic Compounds of Strain JK-13 on Pathogens

[0056] The results of the double-plate test and the cellophane culture test showed that the volatile and non-volatile metabolites produced by strain JK-13 could inhibit the growth of the pathogen F. cugenangense ( Figure 6 ). Compared with the control, the volatile substances produced by strain JK-13 had an inhibition rate of 33.36% on the growth of pathogenic bacteria. Its volatile metabolites had a lower inhibition rate on the pathogenic bacteria F. cugenangense, but its non-volatile metabolites had a higher inhibition rate, reaching 51.41%.

[0057] Example 8 Optimization of culture conditions of strain JK-13

[0058] Effects of different culture media on the antibacterial activity of fermentation broth of strain JK-13

[0059] The seed liquid was inoculated with 2% inoculation amount into 6 commonly used gelatinous Streptomyces culture media (Gao's culture medium, corn infusion culture medium, soybean infusion culture medium, millet infusion culture medium, yeast extract peptone glucose culture medium, yeast malt infusion culture medium), cultured at 28°C and 180r / min for 7 days, and the inhibition rate of the fermentation liquid on pathogens in different culture media was measured to determine the optimal fermentation medium, which was repeated 3 times.

[0060] There were some differences in the inhibitory effects of the strain JK-13 cultured in 6 different culture media on the pathogen F. cugenangense. Among them, the inhibition rate of the millet juice culture medium was the highest, which was 38.77% (P<0.05, Figure 7 a). Therefore, millet extract culture medium was selected as the best fermentation culture medium of JK-13 for subsequent experiments.

[0061] Effects of different carbon sources, nitrogen sources and inorganic salts on the antibacterial activity of the fermentation broth of strain JK-13

[0062] The best fermentation medium screened was used to select the best culture components through single-factor experiments, and the types of carbon, nitrogen sources and inorganic salts in the medium were selected. In order to accurately analyze the correlation between carbon, nitrogen sources and inorganic salts in the medium, the best carbon source, best nitrogen source and best inorganic salt screened were referred to the optimal fermentation basal medium formula, and an orthogonal experiment with 4 factors and 3 levels was designed using the orthogonal design assistant to determine the ratio of the optimal fermentation formula for the antagonistic strain JK13, with the antibacterial rate as the evaluation index.

[0063] The fermentation broths of strain JK-13 obtained by using six carbon sources, nitrogen sources and inorganic salts all had a certain inhibitory effect on the pathogen F. cugenangense. Among them, the fermentation broths of strains with maltose as carbon source, ammonium sulfate as nitrogen source and potassium chloride as inorganic salt had the highest inhibition rates of 42.59%, 47.11% and 31.89% respectively, which were significantly higher than those of other carbon sources ( Figure 7 b) Nitrogen source ( Figure 7 c) Inorganic salts ( Figure 7 d); Therefore, maltose, ammonium sulfate and potassium chloride were selected as the optimal carbon source, nitrogen source and inorganic salt of the culture medium for subsequent orthogonal experiments.

[0064] Orthogonal experiment of nutritional conditions

[0065] According to the test results of carbon source, nitrogen source and inorganic salt, maltose, ammonium sulfate, potassium chloride, CaCO 3 Four factors were included, and a four-factor three-level orthogonal test was conducted (Table 4), and the final fermentation formula was determined based on the antibacterial activity results.

[0066] The larger the range, the greater the impact; conversely, the smaller the range, the smaller the impact. Therefore, the order of the factors affecting the sterile fermentation broth is: ammonium sulfate (A) > potassium chloride (B) > calcium carbonate (C) > maltose (D). According to the mean value of different levels of the same factor, the optimal value of the factor can be determined, and the optimal combination of all factors is A3B2C3D2. However, this formula did not appear in the orthogonal experiment, so a verification test was conducted. JK-13 was fermented again according to the A3B2C3D2 formula, and other conditions remained unchanged. The antibacterial rate was measured to be 51.03%. The results showed that this formula is indeed the best formula, that is, the best culture medium formula is millet 10.0g / L, maltose, 10.0g / L, ammonium sulfate 5.0g / L, potassium chloride 2.5g / L, and calcium carbonate 3.0g / L.

[0067] Table 4 Results of orthogonal experiments on nutrients in fermentation medium of strain JK-13

[0068]

[0069] Example 9 Potted Plant Prevention Test Evaluation

[0070] The two-year-old susceptible tea variety Xiangfeicui was selected as the test material, and surfactants were added to the antagonistic bacteria fermentation liquid and mixed for later use. Healthy tea potted plants with the same growth were selected and divided into 4 groups, namely the pathogen fermentation liquid treatment group, the strain JK-13 fermentation liquid treatment group, the 10-fold strain JK-13 fermentation liquid treatment group, and the 100-fold strain JK-13 fermentation liquid treatment group. The specific operations are as follows: 20mL of pathogen fermentation liquid was used to irrigate the roots of all 4 groups of tea seedlings; after 1 day of pathogen fermentation liquid treatment, 20mL of strain JK-13 fermentation liquid, 10-fold strain JK-13 fermentation liquid, and 100-fold strain JK-13 fermentation liquid were used to irrigate the roots of 3 groups of tea seedlings. The above operations were repeated once on the 14th day, and each treatment was repeated for 4 groups, with 4 potted plants in each group, a total of 64 potted plants, cultured under natural conditions, and their disease status was observed. After 28 days, the incidence rate survey and prevention and control effect evaluation were carried out. The incidence rate and control effect were calculated according to the following formulas:

[0071] Incidence rate (%) = (number of diseased plants / total number of plants) × 100%

[0072] Control effect (%) = (control incidence - treatment incidence) / control incidence × 100%

[0073] Table 5 Evaluation of potted plant protection effect test

[0074] deal with Incidence (%) Control effect (%) Pathogen fermentation broth 100.00％ — Strain JK-13 fermentation stock solution 25.00％ 75.00％ 10 times strain JK-13 fermentation broth 43.75％ 56.25％ 100 times strain JK-13 fermentation broth 56.25％ 43.75％

[0075] The results of the potted plant prevention test showed (Table 5) that 28 days after the inoculation of the pathogen, the incidence rate of the pathogen fermentation liquid group was 100.00%, the incidence rate of tea seedling root rot in the groups treated with strain JK-13 fermentation liquid, 10 times strain JK-13 fermentation liquid and 100 times strain JK-13 fermentation liquid were 25.00%, 43.75% and 56.25%, respectively, and the prevention and control effects of tea seedling root rot were 75.00%, 56.25% and 43.75%, respectively. The fermentation liquid had the best prevention and control effect. Strain JK-13 has great application potential in the prevention and control of tea tree root rot.

[0076] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0077] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A tea root rot antagonistic strain Streptomyces colloidalis JK-13, characterized in that: The Streptomyces gelaticus JK-13 was deposited in the China Center for Type Culture Collection on October 16, 2023, with a collection number of CCTCCNO: M20231912, a collection address of Wuhan University, Wuhan, China, and a classification name of Streptomyces gelaticus JK-13.

2. Use of the Streptomyces colloidales JK-13 according to claim 1 in the preparation of biological preparations for antagonizing strawberry blight pathogen, polygonatum anthracnose pathogen, potato early blight pathogen, wild rice stem fusarium pathogen, citrus scurf pathogen, eggplant brown streak pathogen, pepper wilt pathogen, and corn leaf blight pathogen.

3. Use of the Streptomyces colloidales JK-13 according to claim 1 in the preparation of a biological preparation for antagonizing tea tree root rot pathogens.

4. Use of the bacterial fermentation liquid of Streptomyces colloidales JK-13 according to claim 1 in preparing a biological preparation for antagonizing tea tree root rot pathogens.

5. The use according to claim 4, characterized in that: The fermentation liquid of the Streptomyces colloidus JK-13 is prepared by culturing the Streptomyces colloidus JK-13 in a culture medium composed of 10.0 g / L millet, 10.0 g / L maltose, 5.0 g / L ammonium sulfate, 2.5 g / L potassium chloride, and 3.0 g / L calcium carbonate.

6. The method for preparing the fermentation broth of Streptomyces colloidalis JK-13 according to claim 1, characterized in that: The process includes: using Gao's No. 1 culture medium as the seed culture medium, taking 20 antagonistic strain cakes with a diameter of 5 mm into 200 mL of Gao's No. 1 culture medium, and culturing at 28° C. and 180 r / min for 7 days to obtain the seed solution; inoculating the seed solution into the fermentation medium at a 2% inoculation rate and culturing at 28° C. and 180 r / min for 7 days to obtain the fermentation solution of Streptomyces colloidal JK-13.

Images