A strain of Aspergillus niger and its application in the prevention and treatment of rot diseases

Abstract

The invention discloses a strain of Aspergillus niger and its application in the prevention and treatment of rot diseases. The invention separates an endophytic fungus, Aspergillus niger (Aspergillus niger), from a branch of a pear tree, and the strain number is La2. The registration number of the strain in the General Microbiological Center of the China Microbiological Culture Collection Administration is CGMCC No.40252. The nucleotide sequence of its 18SrDNA contains the DNA molecule shown in sequence 1 in the sequence table. Experiments have shown that Aspergillus niger La2 has a certain inhibitory effect on the bacterial plaque of pear tree rot pathogens and apple tree rot pathogens; the pear tree branches treated with the sterile filtrate or spore suspension of Aspergillus niger La2 can significantly inhibit the growth of pear tree rot pathogens and the incidence of pear branch rot disease. As a biocontrol fungal resource, it has a good application prospect and can be used for safe, effective and environmentally friendly biological control of plant rot diseases.

Description

Technical Field

[0001] The invention relates to the field of biotechnology, and in particular to an Aspergillus niger strain and application thereof in the prevention and treatment of rot diseases. Background Art

[0002] Rot is a common disease on fruit trees, causing serious damage to fruit trees such as pears and apples, affecting the normal fruiting of fruit trees and causing a decrease in yield. The disease is characterized by wide distribution, serious damage, and difficulty in prevention and control. When the disease is severe, it leads to the death of the tree, causing serious economic losses. It is regarded as the "cancer" of forests in fruit and forestry planting areas. The frequent and large-scale occurrence of forest and fruit tree rot has become an important restrictive factor in the development of the fruit and forestry industry and the protection of the ecological environment, and has also posed a serious threat to the economic income of fruit farmers. At present, the prevention and control of fruit tree rot is mainly chemical control, but the long-term use of chemical agents will cause environmental pollution, pesticide residues in fruits and other problems, which violates the basic principle of sustainable agriculture. Therefore, it is urgent to seek more effective alternatives.

[0003] Biological control is highly efficient, safe, and low-toxic. It is an important strategy to replace chemical control to reduce the damage of pear tree rot. It has become the focus of research by scholars at home and abroad. Using plant endophytes and their metabolites to control diseases is one of the important measures of biological control. At present, there are reports on the use of endophytic fungi for crop disease control, such as the use of Trichoderma harzianum to control corn rust, small spot disease, and large spot disease. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to prevent and control rot diseases or how to carry out biological control of plant rot diseases.

[0005] In order to solve the above technical problems, the present invention first provides an Aspergillus niger. The Aspergillus niger is Aspergillus niger, whose strain number is La2 and whose registration number in the General Microbiological Center of China National Microbiological Culture Collection is CGMCC No.40252.

[0006] The nucleotide sequence of the 18S rDNA of Aspergillus niger contains the DNA molecule shown in Sequence 1 in the sequence list; the coding sequence of the microtubule protein of Aspergillus niger contains the DNA molecule shown in Sequence 2 in the sequence list.

[0007] The culture of Aspergillus niger mentioned above also belongs to the protection scope of the present invention. The culture can be a substance obtained by culturing the Aspergillus niger mentioned above in a microbial culture medium (i.e., a fermentation product, such as a fermentation liquid containing Aspergillus niger strain La2 and a substance secreted into a liquid culture medium, or a solid fermentation product containing Aspergillus niger strain La2 and a substance secreted into a solid culture medium).

[0008] In the above culture, the microbial culture medium may be a solid culture medium or a liquid culture medium.

[0009] The term "culture" refers to a general term for liquid or solid products (all substances in the culture container, i.e., fermentation products) that have a microbial population after artificial inoculation and culture. That is, the product obtained by growing and / or amplifying the microorganisms, which may be a biologically pure culture of the microorganisms, or may contain a certain amount of culture medium, metabolites, and / or other components produced during the culture process. The term "culture" also includes a subculture obtained by subculturing the microorganisms, which may be a culture of a certain generation, or a mixture of several generations.

[0010] In order to solve the above technical problems, the present invention further provides a bacterial agent, wherein the active ingredient of the bacterial agent is the above-mentioned Aspergillus niger and / or the metabolite of the above-mentioned Aspergillus niger and / or the culture of the above-mentioned Aspergillus niger.

[0011] In the above, the metabolite of the Aspergillus niger strain La2 may be the fermentation broth, spore suspension or sterile filtrate of the Aspergillus niger strain La2.

[0012] The fermentation broth of Aspergillus niger strain La2 can be prepared as follows: Aspergillus niger strain La2 is cultured in a liquid fermentation medium, and the fermentation broth (containing Aspergillus niger strain La2 and substances secreted into the liquid medium) is collected. The fermentation broth is the metabolite of Aspergillus niger strain La2.

[0013] The spore suspension of Aspergillus niger strain La2 can be prepared according to the following method: Aspergillus niger strain La2 is cultured in a solid fermentation medium, and the spores of Aspergillus niger strain La2 in the solid fermentation medium are eluted with sterile water and then collected (containing the spores of Aspergillus niger strain La2 and substances secreted onto the solid medium), thereby obtaining the spore suspension of Aspergillus niger strain La2.

[0014] The sterile filtrate of Aspergillus niger strain La2 can be prepared according to the following method: the fermentation broth of Aspergillus niger strain La2 is filtered using a microporous filter membrane to obtain the sterile filtrate of Aspergillus niger strain La2.

[0015] In the above-mentioned bacterial agent, the bacterial agent may further include a carrier. The carrier may be a solid carrier or a liquid carrier.

[0016] The above-mentioned bacterial agents may be in various dosage forms, including but not limited to liquid, emulsion, suspension, powder, granule, wettable powder or water dispersible granule, etc.

[0017] The above-mentioned bacterial agent may have at least one of the following characteristics:

[0018] A1) Inhibit plant decay pathogens;

[0019] A2) Inhibit plant rot;

[0020] A3) Prevent and control plant rot diseases.

[0021] In order to solve the above technical problems, the present invention also provides any of the following applications of the Aspergillus niger described above:

[0022] A) Use of the Aspergillus niger described above in the preparation of an inhibitor of plant decay pathogens;

[0023] B) Use of the Aspergillus niger described above in inhibiting plant decay pathogens;

[0024] C) Use of the Aspergillus niger described above in the preparation of a plant rot disease inhibitor;

[0025] D) Use of the Aspergillus niger described above in inhibiting plant rot diseases;

[0026] E) Use of the Aspergillus niger described above in preventing and controlling plant rot diseases.

[0027] In order to solve the above technical problems, the present invention also provides any of the following applications of the culture described above:

[0028] A) Use of the culture described above in the preparation of an inhibitor of plant decay pathogens;

[0029] B) Use of the culture described above for inhibiting plant decay pathogens;

[0030] C) Use of the culture described above in the preparation of a plant rot inhibitor;

[0031] D) Use of the culture described above for inhibiting plant rot diseases;

[0032] E) Use of the culture described above for controlling plant rot diseases.

[0033] In order to solve the above technical problems, the present invention also provides any of the following applications of the above-mentioned bacterial agent:

[0034] A) Use of the above-mentioned bacterial agent in the preparation of an inhibitor of plant rot pathogens;

[0035] B) Application of the above-mentioned microbial agent in inhibiting plant decay pathogens;

[0036] C) Use of the above-mentioned bacterial agent in the preparation of plant rot disease inhibitors;

[0037] D) Application of the above-mentioned bacterial agent in inhibiting plant rot diseases;

[0038] E) Application of the above-mentioned bacterial agent in preventing and controlling plant rot diseases.

[0039] The plant rot pathogens mentioned above may be apple rot pathogens or pear rot pathogens. The plant rot diseases mentioned above may be apple rot disease or pear rot disease.

[0040] In order to solve the above technical problems, the present invention also provides a method for culturing the Aspergillus niger described above. The method may include the step of culturing the Aspergillus niger described above in a microbial culture medium.

[0041] The purpose of the present invention is to address the problems existing in the existing chemical control of rot diseases, provide an endophytic fungus Aspergillus niger isolated from pear tree branches, and utilize its antagonistic effect to carry out a safe, effective and environmentally friendly biological control method for pear tree rot diseases and apple tree rot diseases.

[0042] The present invention isolates endophytic fungi from pear tree branches, and one of the strains is identified as Aspergillus niger by morphology and molecular biology, and is named La2. Subsequently, the present invention adopts a plate confrontation test, and finds that the Aspergillus niger strain has a good inhibitory effect on the growth of pear tree rot pathogens and apple tree rot pathogens, and the inhibition rate reaches more than 80%. Similarly, the filtrate of the Aspergillus niger strain can also significantly inhibit the growth of pear tree rot pathogens and apple tree rot pathogens. Further, the Aspergillus niger spore suspension is used to treat the pear tree branches, and the incidence of rot disease is significantly reduced. These results show that La2, as a biocontrol fungus resource, has a good application prospect in the prevention and control of rot diseases.

[0043] Collection Instructions

[0044] Species name: Aspergillus niger

[0045] Latin name: Aspergillus niger

[0046] Strain ID: La2

[0047] Depository: China National Microbiological Culture Collection Administration General Microbiology Center

[0048] Abbreviation of depository institution: CGMCC

[0049] Address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing

[0050] Date of deposit: July 22, 2022

[0051] CGMCC Registration Number: CGMCC No.40252 BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1The inhibition of endophytic fungus La2 on apple rot pathogens was observed. A: The inhibition of endophytic fungus La2 on apple rot pathogens; the left picture is the control culture medium plate, and the right picture is the culture medium plate with endophytic fungus La2 added. The inhibition of endophytic fungus La2 on pear rot pathogens was observed; the left picture is the control culture medium plate, and the right picture is the culture medium plate with endophytic fungus La2 added.

[0053] Figure 2 This is an observation of the degree of inhibition of endophytic fungus La2 spore suspension (treatment) on pear tree rot branches and trunks. The scale is 1 cm. DETAILED DESCRIPTION

[0054] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0055] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0056] The apple rot pathogen (Valsa mali) in the following examples is preserved in this laboratory. Related literature: Wang L, Hou H, Zhou Z, Tu H, Yuan H. Identification and Detection of Botryosphaeria dothidea from Kiwifruit (Actinidia chinensis) in China. Plants (Basel). 2021 Feb 20; 10 (2): 401. doi: 10.3390 / plants10020401. PMID: 33672451; PMCID: PMC7923295. pyri) is preserved in our laboratory. Related literature: Yuan Hongbo, Hou Hui, Zhou Zengqiang, Wang Li, Tu Hongtao. Isolation and identification of the antagonistic fungus JK2 against pear rot. Journal of Fruit Science. https: / / doi.org / 10.13925 / j.cnki.gsxb.20200141.

[0057] In the following examples, potato dextrose liquid medium (PDB): peel potatoes, cut 200 g into small pieces, add water and boil for 30 min, filter through 4 layers of gauze, add 20 g of glucose, distilled water to 1000 mL, boil and mix, sterilize at 121° C. for 20 min to obtain PDB medium.

[0058] In the following examples, potato dextrose agar medium (PDA) was prepared by peeling potatoes, cutting 200 g of potatoes into small pieces, boiling with water for 30 min, filtering with 4 layers of gauze, adding 20 g of glucose, 17 g of agar, and distilling the mixture to 1000 mL with distilled water, boiling and mixing, and sterilizing at 121° C. for 20 min to obtain PDA medium.

[0059] The experiments in the examples of the present invention were all repeated three times.

[0060] Example 1: Isolation and functional identification of Aspergillus niger strains

[0061] 1. Strain Isolation

[0062] The present invention separates endophytic fungi from the phloem of pear tree branches, and one of the strains is identified as Aspergillus niger by morphology and molecular biology, and is named La2. The separation method is as follows: a 5×5mm pear tree branch tissue block is selected, disinfected with 75% ethanol for 1 minute, and then surface disinfected with 1% NaClO for 5 minutes, then washed with sterile water for 3 times, and the water on the surface of the tissue block is absorbed with sterilized filter paper, and the tissue block is placed on a PDA culture medium (containing 100mg / L kanamycin sulfate), and cultured in an incubator at a constant temperature of 25°C, and observed every 24 hours. After the colony is formed, strains with different colony morphologies are selected and inoculated on a new PDA culture medium, and separated and purified to obtain pure strains. One of the strains is named La2.

[0063] A single colony of strain La2 was picked and added to PDB liquid medium for culture to obtain a fresh culture solution of La2. 1 mL of fresh culture solution was centrifuged at 4°C and 8000 rpm for 5 min, the bacteria were collected in a 2 mL centrifuge tube, and DNA was extracted using a DNA extraction kit. After electrophoresis detection, the 18s rDNA sequence of strain La2 was amplified using primers ITS1 (5'-TCCGTAGGTGAACCTGCGG-3') and ITS4 (5'-TCCTCCGCTTATTGATATGC-3') to obtain a fragment with a length of 600 bp (sequence 1 in the sequence table); and the partial coding sequence of the microtubule protein gene (Tubulin) of strain La2 was amplified using primers Bt2a (5'-GGTAACCAAATCGGTGCTGCTTTC-3') and Bt2b (5'-ACCCTCAGTGTAGTGACCCTTGGC-3') to obtain a fragment with a length of 540 bp (sequence 2 in the sequence table).

[0064] The 18S rDNA sequence of the strain La2 was compared for sequence similarity on the NCBI website. After comparison, the gene sequence was similar to the genus Penicillium (the highest similarity with Aspergillus niger was 100.00%), and the tubulin gene sequence comparison results also showed that the highest similarity with Aspergillus niger was 99.07%. This indicates that the strain La2 belongs to Aspergillus niger of the genus Aspergillus. The colony of strain La2 is round and black. The hyphae are dense, the spore production is large, the conidia are elliptical, and the surface is smooth. According to the "Handbook of Fungal Identification" and other methods, the strain was preliminarily identified as Aspergillus. After amplification and sequencing of its 18SrDNA and Tubulin sequences and sequence comparison using molecular biological techniques, strain La2 was identified as Aspergillus niger, hereinafter referred to as strain La2.

[0065] Aspergillus niger strain La2 was deposited in the General Microbiology Center of China Culture Collection Administration (CGMCC for short, address: No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing) on ​​July 22, 2022, with the deposit number CGMCC No. 40252.

[0066] 2. Detection of the inhibitory function of strain La2 on rot pathogens

[0067] The plate confrontation experiment was used to detect the inhibitory effect of the isolated and purified fungal strains on pear rot and apple rot pathogens.

[0068] The apple rot pathogen (Valsa mali) and the pear tree rot pathogen (Valsa pyri) were inoculated on PDA plates respectively and cultured at 25°C for 4 days. A 5mm diameter puncher was used to punch out the bacterial blocks with consistent colony growth and inoculated them in the center of the PDA plate. The Aspergillus niger strain La2 isolated and purified in step 1 was inoculated 2 cm above, below, left and right of the pathogen as the treatment group. The PDA plates inoculated with only apple rot pathogens or tree rot pathogens (without Aspergillus niger strain La2) were used as the control group. Ten plates were inoculated for each treatment and cultured at a constant temperature of 25°C. Three replicates were performed. After the pathogens in the control group grew all over the culture plate, the inhibition rate was calculated. Inhibition rate (%) = (control colony diameter - treatment colony diameter) / control plate colony diameter × 100%. The same method was used to detect the inhibition of Aspergillus niger strain La2 on pear tree rot pathogens. The results showed that Aspergillus niger strain La2 had a significant inhibitory effect on apple tree rot ( Figure 1 A) and pear rot pathogen ( Figure 1 B) all had a good inhibitory effect (Table 1).

[0069] Table 1. Inhibition rate of endophytic fungus La2 against apple rot pathogen and pear rot pathogen (mean ± SD)

[0070]

[0071] 3. The inhibition of the filtrate of the endophytic fungus Aspergillus niger strain La2 on pear rot pathogens.

[0072] 3.1 Preparation of sterile filtrate

[0073] The Aspergillus niger strain La2 was inoculated on a PDA plate and cultured at 25°C for 7 days to obtain a culture of the Aspergillus niger strain La2. The spores of the culture of the Aspergillus niger strain La2 were washed with sterile water to obtain a spore suspension of the Aspergillus niger strain La2. The concentration was counted with a hemocytometer and adjusted to 10 8 1 mL of spore liquid was inoculated into 50 mL of PDB medium, and cultured at 25°C and 180 r / min for 5 days. The obtained fermentation liquid was centrifuged at 10000 rpm for 20 min, and the supernatant was filtered with a 0.22 μm microporous filter membrane to obtain the sterile filtrate of Aspergillus niger strain La2.

[0074] 3.2 Preparation of virus-infected plates

[0075] Take 5 mL of the sterile filtrate of Aspergillus niger strain La2 and mix it with 95 mL of PDA culture medium cooled to 50°C and pour it into a plate to make a poisonous PDA plate. Replace the sterile filtrate with sterile water and mix it with PDA culture medium to make a non-toxic plate as a blank control CK.

[0076] 3.3 Inhibition of Pear Rot Pathogen by Sterile Filtrate

[0077] Use a 5mm diameter puncher to punch out the colony growth of pear rot pathogens, inoculate them in the center of the infected PDA plate as the treatment group, and inoculate the pear rot pathogens on the non-infected plate as the control group. Inoculate 3 plates each time and culture at a constant temperature of 25℃. Repeat 3 times.

[0078] When the pathogen of pear rot in the control group grew all over the culture dish, the diameter was counted and the inhibition rate was calculated. The results showed that the poisonous PDA plates prepared with the sterile filtrate of Aspergillus niger strain La2 had a significant inhibitory effect on the pathogen of pear rot (Table 2).

[0079] Table 2. Inhibition rate of sterile filtrate of Aspergillus niger strain La2 against pear rot pathogen (mean ± SD)

[0080]

[0081] 4. Inhibition of the incidence of pear rot by sterile filtrate

[0082] The sterile filtrate of Aspergillus niger strain La2 prepared in step 3.1 was uniformly sprayed on one-year-old pear branches as the pear branches of the treatment group (sterile filtrate treatment group); the sterile PDB liquid culture medium was sprayed on one-year-old pear branches as the pear branches of the control group (CK). After spraying, a 5mm diameter puncher was used to punch fungus blocks from the edge of the pear rot bacteria grown for 4 days on the PDA plate, and the fungus blocks were inoculated into the pear branches of the treatment group and the control group, respectively. 10 pear branches were inoculated in each of the treatment group and the control group. 7 days after inoculation, the length of the lesions was investigated.

[0083] The results showed that spraying with the sterile filtrate of Aspergillus niger strain La2 could significantly inhibit the incidence of pear rot pathogens (Table 3): the diameter of the rot spots on the pear branches in the treatment group after spraying with the sterile filtrate of Aspergillus niger strain La2 was significantly smaller than that in the control group (p < 0.01), and the incidence of pear rot pathogens on the pear branches in the treatment group was significantly lower than that in the pear branches in the control group.

[0084] Table 3. Effect of sterile filtrate of Aspergillus niger strain La2 on the incidence of pear rot

[0085] Lesion length (cm) CK control group 3.07±0.27 Sterile filtrate treatment group 1.15±0.14

[0086] 5. Inhibition of the incidence of pear rot pathogens by spore suspension of Aspergillus niger strain La2

[0087] 50 mL of the spore suspension (10 850 mL of sterile PDB liquid medium was sprayed on one-year-old pear branches as the treatment group pear branches (spore suspension treatment group); 50 mL of sterile PDB liquid medium was sprayed on one-year-old pear branches as the control group pear branches (CK). After spraying, a 5 mm diameter puncher was used to punch fungus blocks from the edge of the 4-day-old pear rot pathogen on the PDA plate, and the fungus blocks were inoculated on the treatment group and control group pear branches, respectively. Ten pear branches were inoculated in each of the treatment group and the control group. Seven days after inoculation, the length of the lesions was investigated.

[0088] The results showed that the use of Aspergillus niger La2 spore suspension spraying treatment can significantly inhibit the incidence of pear rot bacteria (Table 4, Figure 2 ): Pear branches in the treatment group after spraying with spore suspension of Aspergillus niger strain La2 ( Figure 2 The diameter of the rot lesions of the 24 samples (shown in the “treatment”) was significantly smaller than that of the control group (p < 0.01) ( Figure 2 The incidence of pear branch rot in the treatment group was significantly lower than that in the control group.

[0089] Table 4. Effect of Aspergillus niger La2 spore suspension on the incidence of pear rot

[0090] Lesion length (cm) CK control group 3.46±0.31 Spore suspension treatment group 1.03±0.26

[0091] The above results show that the pear tree endophytic fungus Aspergillus niger strain La2 and its sterile filtrate and spore suspension discovered in the present invention can be used for biological control of plant rot diseases. Aspergillus niger strain La2, as a biocontrol fungus resource, has a good application prospect in the prevention and control of rot diseases.

[0092] The present invention has been described in detail above. It will be apparent to those skilled in the art that the present invention may be implemented in a wide range under equivalent parameters, concentrations and conditions without departing from the spirit and scope of the present invention and without the need for unnecessary experimentation. Although the present invention provides specific embodiments, it should be understood that further improvements may be made to the present invention. In short, according to the principles of the present invention, this application intends to include any changes, uses or improvements to the present invention, including changes made by conventional techniques known in the art that depart from the scope disclosed in this application. Applications of some of the basic features may be made within the scope of the following appended claims.

Claims

1. Aspergillus niger, characterized in that: The Aspergillus niger is Aspergillus niger ( Aspergillus niger ) La2, whose registration number in the General Microbiological Center of China Culture Collection Administration is CGMCC No.40252.

2. Aspergillus niger according to claim 1, characterized in that: The nucleotide sequence of the 18SrDNA of Aspergillus niger contains the DNA molecule shown in Sequence 1 in the sequence table; the coding sequence of the microtubule protein of Aspergillus niger contains the DNA molecule shown in Sequence 2 in the sequence table.

3. A bacterial agent, characterized in that: The active ingredient of the bacterial agent is the Aspergillus niger described in claim 1 or 2.

4. The bacterial agent according to claim 3, characterized in that: The bacterial agent has at least one of the following characteristics: A1) Inhibit plant decay pathogens; A2) Inhibit plant rot; A3) Prevent and control plant rot; The plant rot pathogen is apple rot pathogen Valsamali Pyrus rot Valsa pyri ; The plant rot disease is apple rot or pear rot; Malus rot Valsamali cause; Pear rot pathogen Valsa pyri cause.

5. Any of the following uses of the Aspergillus niger described in claim 1 or 2: A) Use of the Aspergillus niger according to claim 1 or 2 in the preparation of an inhibitor of plant decay pathogens; B) Use of the Aspergillus niger described in claim 1 or 2 in inhibiting plant decay pathogens; C) Use of the Aspergillus niger according to claim 1 or 2 in the preparation of a plant rot disease inhibitor; D) Use of Aspergillus niger according to claim 1 or 2 in inhibiting plant rot diseases; E) Use of the Aspergillus niger according to claim 1 or 2 in preventing and treating plant rot diseases; The plant rot pathogen is apple rot pathogen Valsamali Pyrus rot Valsa pyri ; The plant rot disease is apple rot or pear rot; Malus rot Valsamali cause; Pear rot pathogen Valsa pyri cause.

6. Any of the following uses of the culture of Aspergillus niger according to claim 1: A) use of the culture in the preparation of an inhibitor of plant decay pathogens; B) use of the culture in inhibiting plant decay pathogens; C) Use of the culture in the preparation of plant rot inhibitors; D) Use of the culture in inhibiting plant rot; E) Use of the culture in preventing and controlling plant rot diseases; The culture is the spore suspension of Aspergillus niger according to claim 1 or the sterile filtrate obtained by fermentation and filtration of the spore suspension of Aspergillus niger according to claim 1; The plant rot pathogen is apple rot pathogen Valsamali Pyrus rot Valsa pyri ; The plant rot disease is apple rot or pear rot; Malus rot Valsamali cause; Pear rot pathogen Valsa pyri cause.

7. Any of the following uses of the bacterial agent according to claim 3 or 4: A) Use of the bacterial agent according to claim 3 or 4 in the preparation of an inhibitor of plant rot pathogens; B) Use of the bacterial agent according to claim 3 or 4 in inhibiting plant decay pathogens; C) Use of the bacterial agent according to claim 3 or 4 in the preparation of a plant rot disease inhibitor; D) Use of the bacterial agent according to claim 3 or 4 in inhibiting plant rot; E) Use of the bacterial agent according to claim 3 or 4 in preventing and controlling plant rot diseases; The plant rot pathogen is apple rot pathogen Valsamali Pyrus rot Valsa pyri ; The plant rot disease is apple rot or pear rot; Malus rot Valsamali cause; Pear rot pathogen Valsa pyri cause.

8. A method for culturing the Aspergillus niger according to claim 1 or 2, comprising the step of culturing the Aspergillus niger according to claim 1 or 2 in a microbial culture medium.

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