Mango endophyte MGL-B1 and application thereof

Abstract

The invention relates to mango endophyte MGL-B1 and application thereof, and belongs to the technical field of biology. The invention provides a mango endophyte MGL-B1 (Bacillus velezensis MGL-B1), and the preservation number of the mango endophyte MGL-B1 is GDMCC (China General Microbiological Culture Collection Center) NO: 65594. The strain, a fungicide prepared from the MGL-B1 and volatile organic compounds produced by the fungicide have a remarkable inhibition effect on pathogenic bacteria of the mango stem-end rot. According to the invention, the problems of environmental pollution and pathogen resistance caused by the traditional chemical control method are solved, an environment-friendly and efficient biological control scheme is provided, and the MGL-B1 as the endophyte is strong in ecological adaptability and wide in antibacterial spectrum, and has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of microorganisms, and particularly relates to an endophytic bacterium of mango and its application. Background Art

[0002] Mango (Mangifera indica L.), belonging to the genus Mangifera of the Anacardiaceae family, is the second largest tropical fruit in the world. In recent years, with the continuous expansion of the mango planting scale, its pest and disease problems have become increasingly prominent. Among them, mango stem-end rot, as the second largest mango disease in the world, has a disease fruit rate of up to 40% in severe cases. This disease can infect mango fruits and cause them to rot, and can also infect the stems and leaves of mangoes, seriously hindering the normal growth of mango plants. It not only poses a serious threat to the yield and quality of mangoes, but also poses a major challenge to the sustainable development of the mango industry.

[0003] At present, the control methods for mango stem-end rot are limited, and mainly chemical control methods are used. Common chemical agents include benomyl, carbendazim, isoproturon, thiabendazole, etc. However, long-term and excessive use of chemical agents will induce the pathogen to develop drug resistance, thus reducing the control effect. At the same time, pesticide residues will also cause problems such as environmental pollution and human and livestock poisoning. In addition, the ban on highly toxic pesticides has also increased the difficulty of selecting chemical control methods.

[0004] In recent years, with the popularization of the concepts of green control and sustainable development, the demand for environmentally friendly biological control resources has been increasing and has received extensive attention. At present, a variety of antagonistic bacteria have been proven to have good control effects on mango stem-end rot. For example, Kloeckera apiculata 3-110 inhibits the invasion of Lasiodiplodia theobromae by scavenging reactive oxygen species in fruits and protecting the cell wall structure, thereby controlling mango stem-end rot. The non-volatile metabolites of Trichoderma pinnatum LS029-3 can reduce the decay rate by increasing the activities of mango defense enzymes (polyphenol oxidase, peroxidase, total phenols), and significantly weaken the incidence degree and lesion area of mango stem-end rot, effectively delaying the decay of fruits. However, current research mainly focuses on the screening and application of exogenous antagonistic bacteria. Due to the poor environmental adaptability of exogenous antagonistic bacteria and their relatively complex action mechanisms and ecological characteristics, it is difficult to achieve large-scale application and promotion.

[0005] Patent CN113817628A discloses a bactericide against mango stem-end rot pathogen and its application. The bactericide against mango stem-end rot pathogen of this technology has a relatively high bactericidal efficiency, but there are certain difficulties and deficiencies in aspects such as ecological adaptability, antibacterial broad-spectrum property, antibacterial mechanism, ecological safety, and actual application and promotion. Problems such as the survival rate, colonization ability of exogenous microorganisms in actual application, and their interaction with plants and the environment limit its popularization and application.

[0006] In contrast, endophytic antagonistic bacteria have the ability to colonize inside plants, can promote the growth of host plants and enhance their stress resistance. When endophytes enter the tissues of host plants, they utilize the internal structure of plants as a special protective ecological niche, thereby effectively enhancing the tolerance of host plants. Endophytes and host plants have formed a mutually beneficial symbiotic relationship during the long-term evolution process, which makes endophytes promising ideal candidates for biological control agents. Therefore, it is necessary to actively explore and screen mango endophytic antagonistic bacteria from various tissues of mangoes to provide new options for the biological control of mango stem-end rot.

[0007] Bacillus velezensis is a biocontrol strain with important application value. This strain can synthesize various antibacterial active substances such as lipopeptides and polyketides, showing broad-spectrum antibacterial characteristics. At the same time, this strain can also promote plant growth and induce plant systemic resistance (ISR). Research shows that Bacillus velezensis has a significant antagonistic effect against a variety of plant pathogens and has been successfully applied to the biological control of plant diseases such as sorghum Fusarium stalk rot, citrus blue mold, tomato gray mold, and banana wilt. However, in the field of mango disease control, the existing technology mainly focuses on mango anthracnose, and there are few studies on the biological control of mango stem-end rot. Therefore, developing the application of Bacillus velezensis in the field of mango stem-end rot control not only expands the application scope of Bacillus velezensis but also provides a new technical solution for the green prevention and control of postharvest diseases of mangoes, with important application value and market prospects. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a mango endophyte and its application.

[0009] To achieve the above purpose, the present invention provides the following technical solutions:

[0010] The present invention provides a mango endophyte MGL-B1, classified and named as: Bacillus velezensis MGL-B1, and the preservation number is: GDMCC NO:65594;

[0011] Furthermore, a bacterial agent prepared from the mango endophyte MGL-B1;

[0012] Furthermore, volatile organic compounds produced by culturing and fermenting the endophytic fungus MGL-B1 of mango;

[0013] The volatile organic compounds include at least one of 2-Dodecanone, 2-Heptadecanol, 2-Hexadecanol, 2-Nonadecanone, 2-Nonanol, 2-Nonanone, 2-Tridecanol, 2-Tridecanone, 6,10,14-Trimethyl-pentadecan-2-ol, Acetoin, Pentadecanoic acid, Phenylethyl Alcohol, 2-Decanone, 3-Octadecene, (E)-, Benzamide, Eicosanoic acid, Hexadecane, Pentadecanoic acid, ethyl ester, Phenol, 3,5-bis(1,1-dimethylethyl)-;

[0014] Furthermore, the application of the microbial agent in preventing and treating mango stem-end rot;

[0015] Furthermore, the application of the volatile organic compounds in preventing and treating mango stem-end rot;

[0016] Furthermore, the application of the microbial agent in preventing and treating plant pathogenic fungi;

[0017] Furthermore, the application of the volatile organic compounds in preventing and treating plant pathogenic fungi;

[0018] The plant pathogenic fungi are at least one of Verticillium dahliae, Piricularia oryzae, Alternaria brassicae, Fusarium moniliforme, Botrytis cinerea.

[0019] The beneficial effects of the present invention are as follows:

[0020] An endophyte MGL-B1 (Bacillus velezensis) was isolated and identified from the leaves of mangoes in Panzhihua, Sichuan Province, China, and has the following advantages:

[0021] 1. High antibacterial efficiency. The inhibition rate of strain MGL-B1 against the pathogen of mango stem-end rot (Botryosphaeria dothidea) reaches 75% - 80%, and the inhibition rate of its volatile metabolites (VOCs) against the mycelial growth of the pathogen exceeds 50%. The control effect on postharvest mango stem-end rot in vitro reaches 80% - 85%, which is significantly better than traditional chemical control.

[0022] 2. Broad-spectrum antibacterial property. Strain MGL-B1 and its VOCs show antagonistic effects against 5 plant pathogenic fungi (Verticillium dahliae, Pyricularia oryzae, Alternaria brassicicola, Fusarium moniliforme, Botrytis cinerea), indicating its broad antibacterial spectrum.

[0023] 3. Environmental friendliness. By replacing chemical agents (such as benomyl and carbendazim) with biological control, the problems of pathogen drug resistance, environmental pollution and pesticide residues caused by chemical control are solved.

[0024] 4. Ecological advantages of endophytes. As an endophyte of mango, MGL-B1 can colonize in the host plant and enhance the stress resistance of the host by utilizing the internal ecological niche of the plant (background technology). Compared with exogenous bacteria, it has stronger environmental adaptability and stability and is more easily promoted and applied.

[0025] 5. Dual action mechanism. While the bacteria directly inhibit the growth of the pathogen, the VOCs produced by it (such as 19 compounds including 2-dodecanone and 3-hydroxy-2-butanone) achieve synergistic antibacterial effect by destroying the cell membrane permeability of the pathogen, providing multiple prevention and control approaches.

[0026] 6. Broad application prospects. As a new use of Bacillus velezensis, MGL-B1 expands the application of this strain in the field of mango disease control, and the bacterial agents and VOCs prepared by it can be produced on a large scale, having market potential.

[0027] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, wherein:

[0029] Figure 1This is the morphological characteristic diagram of the biocontrol bacterium MGL-B1 of the present invention, specifically: the single colony morphology of the MGL-B1 strain on the LB plate (A), Gram staining (B), and scanning electron microscopy (C);

[0030] Figure 2 This is the phylogenetic tree diagram of the biocontrol bacterium MGL-B1 of the present invention;

[0031] Figure 3 This is the diagram of the effect of the biocontrol bacterium MGL-B1 of the present invention on the mycelium of the pathogenic bacterium MGF-F1. Specifically, A and B are the mycelium morphology of the normal-growing MGF-F1 on the plate and the mycelium morphology under scanning electron microscopy, respectively, and C and D are the mycelium morphology of the MGF-F1 on the plate treated with MGL-B1 and the mycelium morphology under scanning electron microscopy, respectively;

[0032] Figure 4 This is the diagram of the effect of the biocontrol bacterium MGL-B1 of the present invention on the cell membrane permeability of the mycelium of the pathogenic bacterium MGF-F1;

[0033] Figure 5 This is the plate diagram of the inhibitory effect of the biocontrol bacterium MGL-B1 of the present invention on 5 strains of pathogenic fungi;

[0034] Figure 6 This is the phenotypic diagram of the inhibitory effect of the volatile metabolites of the biocontrol bacterium MGL-B1 of the present invention on the pathogenic bacterium MGF-F1;

[0035] Figure 7 This is the diagram of the effect of the volatile metabolites of the biocontrol bacterium MGL-B1 of the present invention on the growth area of the pathogenic bacterium MGF-F1;

[0036] Figure 8 This is the composition characterization of the VOCs produced by the biocontrol bacterium MGL-B1 of the present invention. The VOCs components produced by the strain MGL-B1 on the LB plate after 4 days and 6 days of inoculation were analyzed by HS-SPME / GC-MS technology, with 3 replicates for each time point; the relative content was represented by the relative peak area of a single compound, and the VOCs produced by the strain MGL-B1 at both 4 days and 6 days were indicated in red font.

[0037] Figure 9 This is the biocontrol effect diagram of the biocontrol bacterium MGL-B1 of the present invention on postharvest mango stem-end rot. Detailed implementation mode

[0038] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0039] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0040] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0041] Example 1. Isolation, identification and antagonistic activity of strain MGL-B1

[0042] The inventors of the present invention isolated and identified an endophyte MGL-B1 from mango leaves in Panzhihua, Sichuan Province, China. After identification, the bacterium was classified as Bacillus velezensis. Experiments have confirmed that the MGL-B1 bacteria and its volatile metabolites have a significant inhibitory effect on mango stem rot. A mango endophyte MGL-B1, classified and named: Bacillus velezensis. Bacillus velezensis MGL-B1 has been deposited in the Guangdong Provincial Microbiological Culture Collection Center on March 5, 2025, with the deposit number: GDMCC NO: 65594. The address of the deposit unit is 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou. Deposit unit code: GDMCC-Guangdong Provincial Microbiological Culture Collection Center.

[0043] 1. Isolation of strain MGL-B1

[0044] In August 2022, mango plant samples affected by mango stem-end rot were collected in Panzhihua City, Sichuan Province. The gradient dilution method and confrontation culture method were used to isolate and screen strains, and 4 antagonistic bacteria were successfully screened out, which had antagonistic effects on the pathogen MGF-F1 (Botryosphaeria dothidea) of mango stem-end rot. Among them, the endophytic bacterium MGL-B1 isolated from diseased mango leaves had the strongest antibacterial activity.

[0045] The strain MGL-B1 was further purified by the continuous streaking method to obtain a single colony of MGL-B1 for subsequent research.

[0046] II. Identification of strain MGL-B1

[0047] Based on the morphological, physiological and biochemical characteristics and molecular biology results of strain MGL-B1, it was finally identified as

[0048] Bacillus velezensis. The identification results are as follows:

[0049] 1. Morphological characteristics of strain MGL-B1

[0050] Strain MGL-B1 grew on LB medium. The colonies were light yellow, with a wrinkled surface and irregular edges (see Figure 1 A), and it was a Gram-positive bacterium (see Figure 1 B). At the same time, under the scanning electron microscope, the cell morphology was rod-shaped and the surface was smooth (see Figure 1 C).

[0051] 2. Physiological and biochemical characteristics

[0052] The physiological and biochemical characteristics of strain MGL-B1 are shown in Table 1.

[0053] Table 1 Physiological and biochemical characteristics of strain MGL-B1

[0054]

[0055] Note: "+" indicates a positive reaction, and "-" indicates a negative reaction

[0056] 3. Molecular biology identification of strain MGL-B1

[0057] Method: The genomic DNA of strain MGL-B1 was extracted using the Bacteria Genomic DNA Kit (Beijing ComWin Biotech Co., Ltd.). The 16S rRNA gene was amplified using the bacterial universal primers 27F (5'-AGAGTTTCATCCTGCCTCAG-3') and 1492R (5'-CGTIACCTTGTTACGACTT-3'). After the PCR amplification products were separated and purified by 1% agarose gel electrophoresis, they were sent to Shanghai Sangon Biotech Co., Ltd. for DNA sequence sequencing.

[0058] The sequencing results are as follows:

[0059] Using 27F as the primer, the genomic nucleotide sequence of strain MGL-B1 was sequenced as shown in SEQ ID NO:2.

[0060] Using 1492R as the primer, the genomic nucleotide sequence of strain MGL-B1 was sequenced as shown in SEQ ID NO:3.

[0061] The assembled sequence of 27F and 1492R was as shown in SEQ ID NO:1.

[0062] The sequencing results were subjected to combined clustering analysis using MEGA7.0 software ( Figure 2 ), and a phylogenetic tree was constructed using the neighbor-joining method, with the stepwise test value set to 1000 times. Combining morphological and physiological and biochemical characteristics, this bacterium was identified as Bacillus velezensis.

[0063] III. Antibacterial Activity of Strain MGL-B1 against the Pathogen of Mango Stem-End Rot

[0064] Using the pathogen MGF-F1 (Botryosphaeria dothidea) of mango stem-end rot isolated and identified by our team in the early stage as the target pathogen, antagonistic screening was carried out on the isolated strain MGL-B1. A pathogen cake with a diameter of 5 mm was inoculated in the center of the PDA medium. Using the four-point confrontation method, 6 μL of the MGL-B1 bacterial solution was inoculated at a distance of 2 cm from the pathogen. The plate inoculated only with the pathogen MGF-F1 was used as a control, and each treatment was repeated three times. The inoculated medium was placed in the dark at 26°C for 3 - 5 d, and the diameter of the pathogen colony was measured using the cross-cross method.

[0065]

[0066] Observe the growth of the pathogenic bacterium when co-cultured with the strain MGL-B1 and without co-culture. The mycelial growth of the pathogenic bacterium in the co-culture treatment group was significantly inhibited, with an obvious antibacterial zone appearing, and the antibacterial rate was 75% - 80%( Figure 3 A, B). The mycelial morphology of the pathogenic bacterium in the treatment group and the control group was observed using a scanning electron microscope, and it was found that the mycelial structure of MGF-F1 was severely damaged. The mycelia of MGF-F1 in the control group were plump, with uniform thickness, and there were obvious attachments on the surface( Figure 3 C); while the mycelia of MGF-F1 in the experimental group showed significant morphological differences, manifested as uneven thickness, accompanied by atrophy, wrinkles, and fractures, etc., there were no attachments on the surface, and some mycelia had kinking phenomena( Figure 3 D). The viability of the mycelia of the pathogenic bacterium in the treatment group and the control group was detected by the FDA-PI double-fluorescence staining method. The results showed that most of the mycelia of the pathogenic bacterium in the control group emitted green fluorescence, and only some of the aging mycelia showed weak red fluorescence; while most of the mycelia of the pathogenic bacterium in the treatment group emitted red fluorescence, and only some of the mycelia showed extremely weak green fluorescence( Figure 4 ). This indicates that the strain MGL-B1 severely damaged the mycelia of the pathogenic bacterium MGF-F1.

[0067] Example 2: Inhibitory effect of strain MGL-B1 on common plant pathogenic fungi

[0068] Taking Verticillium dahliae, Piricularia oryzae, Alternaria brassicae, Fusarium moniliforme, and Botrytis cinerea as the tested pathogenic bacteria respectively. A pathogenic bacterium cake with a diameter of 5 mm was inoculated in the center of the PDA medium, and 6 μL of the MGL-B1 bacterial solution was inoculated at a distance of 2.5 cm from the pathogenic bacterium using the two-point confrontation method. The plate inoculated only with the pathogenic bacterium was used as the control, and each treatment was repeated three times. The inoculated medium was placed in the dark at 26°C for 5 - 7 d, and the diameter of the pathogenic bacterium colony was measured using the cross method.

[0069] For the antagonistic screening of the above 5 common plant pathogenic fungi, the antagonistic bacterium MGL-B1 had different degrees of inhibitory effects on the 5 pathogenic fungi( Figure 5 ), and the antibacterial rate reached more than 58% (Table 2). It is worth mentioning that the inhibitory effect of the strain MGL-B1 on Piricularia oryzae was the most significant, and the antibacterial rate was as high as 81.97%. This indicates that MGL-B1 can effectively inhibit the growth of various pathogenic bacteria and is a good broad-spectrum antagonistic microorganism.

[0070] Table 2 Antibacterial rate of MGL-B1 strain against 5 pathogenic fungi

[0071]

[0072] Example 3: Analysis of the antibacterial activity of the volatile metabolites of strain MGL-B1

[0073] Using the plate inversion method, the PDA plate inoculated with the pathogenic bacterium was inverted on the LB plate inoculated with 100 μL of the antagonistic bacterium solution. The plate inoculated with an equal amount of sterile water was used as a control. Each treatment was repeated three times and cultured in an incubator at 26 °C. Observe the growth of the pathogenic bacterium every 24 h for 6 consecutive days. The dynamic growth area of the pathogenic bacterium was calculated using Image J software, and in-depth data processing was carried out using Graphpad Prism 9.5 win software.

[0074] The results are as Figure 6 、 7 shown. The volatile substances produced by the antagonistic bacterium MGL-B1 significantly inhibited the growth of the pathogenic bacterium MGF-F1. At 6 days of culture, the colony area of the treatment group was 25.64 cm 2 , and the colony area of the control group was about 4 times that of the treatment group (P < 0.01). This indicates that there are active substances in the volatile metabolites of strain MGL-B1 that have a significant inhibitory effect on the growth of the pathogenic bacterium MGF-F1.

[0075] Example 4: Identification of the components of the volatile metabolites of strain MGL-B1

[0076] The VOCs components produced by the biocontrol bacterium MGL-B1 were determined by SPME-GC-MS. The slant of strain MGL-B1 was inoculated into a 20 mL headspace vial containing LB solid medium and cultured at 37 °C in the dark for 4 days and 6 days respectively, and the components were measured in turn. Then, headspace solid-phase microextraction (HS-SPME: DVB / CAR / PDMS) was used for injection, and the GC part was selected to use an Rtx-WAX chromatographic column for separation.. Known substances were identified by comparison using the National Institute of Standards and Technology 2014 (NIST 14) database in the United States. A similarity of ≥ 90% was considered a successful match, and the relative content was replaced by the proportion of the single peak area.

[0077] The results are as Figure 8As shown in the figure, a total of 52 VOCs (similarity ≥ 90%) were identified by HS-SPME / GC-MS. Among them, 12 VOCs were jointly produced by the 4-day and 6-day cultures of strain MGL-B1, namely 2-Dodecanone, 2-Heptadecanol, 2-Hexadecanol, 2-Nonadecanone, 2-Nonanol, 2-Nonanone, 2-Tridecanol, 2-Tridecanone, 6,10,14-Trimethyl-pentadecan-2-ol, Acetoin, Pentadecanoic acid, and Phenylethyl Alcohol. In addition, strain MGL-B1 produced 7 specific VOCs at 6 days, namely 2-Decanone, 3-Octadecene, (E)-, Benzamide, Eicosanoic acid, Hexadecane, Pentadecanoic acid, ethyl ester, and Phenol, 3,5-bis(1,1-dimethylethyl)-.

[0078] Example 5. Biocontrol effect of strain MGL-B1 on postharvest mango stem-end rot

[0079] For in vitro mango inoculation, Panzhihua coconut-scented mangoes with similar size, shape, color, consistent maturity, and no wounds were selected as test materials. After rinsing the surface impurities with distilled water, the mangoes were soaked in 2% sodium hypochlorite solution for 2 min, then washed with distilled water 3 - 5 times and air-dried. The treated mangoes were randomly and evenly divided into two parts. Sterile toothpicks were used to create wounds of uniform size and depth on the surface of each mango fruit. 90 μL of the antagonistic bacterium MGL-B1 bacterial solution was added to each wound in the treatment group, while 90 μL of sterile water was added to each wound in the control group. After placing them at room temperature for 12 h, a pathogen cake with a diameter of 5 mm was inoculated on the wound surface, and they were incubated in the dark in an incubator at a constant temperature of 22°C and a relative humidity of 85 - 95%. The lesion area of the mangoes was photographed and recorded every 24 h for 6 consecutive days. The Image J software was used to calculate the dynamic change area of the lesion area.

[0080]

[0081] The results are as Figure 9As shown, with the extension of the treatment time, large areas of rot symptoms appeared in the control group, while the lesion area of mango fruits in the treatment group increased slowly and was significantly lower than that in the control group. The biocontrol efficacy of the antagonistic bacterium MGL-B1 against postharvest mango stem-end rot reached 80% - 85%. This indicates that strain MGL-B1 has good biocontrol efficacy against postharvest mango stem-end rot.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. Mango endophyte MGL-B1, characterized in that: The classification name is: Bacillus velezensis MGL-B1, and the deposit number is: GDMCC NO:65594.

2. A bacterial agent prepared using the mango endophyte MGL-B1 according to claim 1.

3. Volatile organic compounds produced by culturing and fermenting the mango endophyte MGL-B1 according to claim 1.

4. The volatile organic compound according to claim 3, characterized in that The volatile organic compounds include 2-dodecane, 2-heptadecanol, 2-hexadecanol, 2-nonadecanone, 2-nonanol, 2-nonanone, 2-tridecanol, 2-tridecanone, 6,10,14-trimethyl-pentadecan-2-ol, 3-hydroxy-2-butanone (Acetoin), pentadecanoic acid, phenethyl alcohol, 2-decanone, 3-octadecene, (E)-, benzamide, eicosanoic acid, hexadecane, pentadecanoic acid, ethyl ester (pentadecanoic acid, ethyl ester) and so on. ester), 3,5-di-tert-butylphenol (Phenol,3,5-bis(1,1-dimethylethyl)-).

5. Use of the bacterial agent according to claim 2 in preventing and treating mango stem rot.

6. Use of the volatile organic compound according to claim 4 in preventing and treating mango stem rot.

7. Use of the microbial agent according to claim 2 in preventing and controlling plant pathogenic fungi.

8. Use of the volatile organic compound according to claim 4 in preventing and controlling plant pathogenic fungi.

9. The use according to claim 7 or 8, characterized in that: The plant pathogenic fungus is at least one of Verticillium dahliae, Piricularia oryzae, Alternariabrassicae, Fusarium moniliforme and Botrytis cinerea.

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