Application of guilliermondia magnoliae jy19 in preventing and controlling botrytis cinerea of panax ginseng

Abstract

The application discloses an application of Gujeromyces JY19 in preventing and controlling ginseng gray mold, and relates to the field of biological control. A Gujeromyces JY19 is separated and screened from under-forest ginseng. The strain exhibits significant antagonism to ginseng gray botrytis, can significantly inhibit the growth of the gray botrytis and the formation of mycelial structure, effectively reduces the incidence of the gray mold of medicinal plants such as ginseng, and significantly enhances the resistance of the medicinal plants such as ginseng to the gray mold.

Description

Technical Field

[0001] This invention relates to the field of biological control, and more specifically, to the application of a yeast strain called *Gnaphalium affine* JY19 in the control of gray mold in ginseng. Background Technology

[0002] Ginseng ( Panax ginseng Ginseng (CA ginseng) is an important traditional Chinese medicine and economic crop in my country. The content and composition of its medicinal components directly determine its efficacy and market value. Diseases not only reduce ginseng yield but also severely affect the accumulation of its medicinal components, thus impacting the quality of the ginseng. Therefore, strengthening effective disease control in ginseng cultivation is of great significance for ensuring the quality of the medicinal material and the sustainable development of the ginseng cultivation industry. Currently, more than 40 diseases affecting ginseng have been reported, mainly including gray mold, black spot, rust rot, and root rot.

[0003] Gray mold is caused by Botrytis cinerea ( Botrytis cinerea Gray mold is a necrotic fungal disease affecting a broad spectrum of hosts. In recent years, the incidence of gray mold in ginseng cultivation has been increasing year by year. According to relevant surveys, since 2002, the incidence rate in some areas has reached 15% to 30%, and in severely affected areas it has even exceeded 50%. Gray mold mainly infects ginseng leaves and petioles, usually starting from the leaf tip or margin and expanding in an inverted V-shape along the veins. In the early stages of the disease, water-soaked grayish-brown spots appear on the leaf surface. As the pathogen colonizes the leaves, the lesions rapidly expand and form a gray mold layer on both sides of the leaf. In the later stages, the leaf lesion tissue necroses, perforates, or falls off, leading to leaf shrinkage, reduced ginseng yield, and poor quality. Therefore, gray mold poses a serious threat to the green and sustainable development of the ginseng and other medicinal plant cultivation industry, and there is an urgent need to develop biocontrol agents that can function stably in the field and meet the safety standards for medicinal materials.

[0004] Due to Botrytis cinerea ( B. cinerea The rapid reproduction, high mutation rate, and easy development of drug resistance of Botrytis cinerea increase the difficulty of field control. Currently, the control of Botrytis cinerea mainly relies on chemical fungicides and resistant varieties. However, due to the genetic variation and drug resistance of the pathogen, the long-term effectiveness of chemical control is limited. At the same time, agricultural chemicals also bring problems such as residues, environmental pollution, and public health risks. Furthermore, existing biocontrol agents are difficult to stably colonize and maintain their effectiveness in ginseng cultivation, resulting in less than ideal field application results.

[0005] Therefore, this invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an application of *Saccharomyces cerevisiae* JY19 in the prevention and control of gray mold in ginseng.

[0007] This invention is implemented as follows:

[0008] In a first aspect, embodiments of the present invention provide a yeast strain JY19, whose taxonomic Latin name is... Meyerozyma guilliermondii The sample is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 34980. Secondly, embodiments of the present invention provide a yeast preparation of *Saccharomyces cerevisiae* JY19 as described in the foregoing embodiments.

[0009] Thirdly, embodiments of the present invention provide cell-free supernatant of *Saccharomyces cerevisiae* JY19 as described in the foregoing embodiments.

[0010] Fourthly, embodiments of the present invention provide volatile organic compounds of *Saccharomyces cerevisiae* JY19 as described in the foregoing embodiments.

[0011] Fifthly, embodiments of the present invention provide a biocontrol agent comprising: the *Saccharomyces cerevisiae* JY19 described in the foregoing embodiments, the bacterial agent described in the foregoing embodiments, the cell-free supernatant described in the foregoing embodiments, or the volatile organic compound described in the foregoing embodiments.

[0012] Sixthly, embodiments of the present invention provide the application of *Saccharomyces cerevisiae* JY19, the fungal agent, the cell-free supernatant, the volatile organic compound, or the biocontrol agent as described in the foregoing embodiments in the control of gray mold in medicinal plants such as ginseng.

[0013] Seventhly, embodiments of the present invention provide the application of *Saccharomyces cerevisiae* JY19, the fungal agent, the cell-free supernatant, the volatile organic compound, or the biocontrol agent as described in the foregoing embodiments in controlling *Botrytis cinerea*. The present invention has the following beneficial effects:

[0014] This invention successfully isolated and identified a strain of *Saccharomyces cerevisiae* JY19. This strain exhibits significant antagonistic activity against *Botrytis cinerea* through multiple mechanisms, including the production of antagonistic metabolites and competition for nutrients and spatial sites. It can significantly inhibit the growth and hyphal structure formation of *Botrytis cinerea*, effectively reduce the incidence of gray mold in medicinal plants (such as ginseng), and significantly enhance the resistance of medicinal plants to gray mold, thereby ensuring their yield and quality. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 for Meyerozyma guilliermondii JY19 morphology diagram;

[0017] Figure 2 for Meyerozyma guilliermondii JY19 phylogenetic tree;

[0018] Figure 3 for Meyerozyma guilliermondii JY19 and Botrytis cinerea Confrontation and cultivation;

[0019] Figure 4 for Meyerozyma guilliermondii JY19 CFS Botrytis cinerea The impact on growth;

[0020] Figure 5 for Meyerozyma guilliermondii JY19 VOCs Botrytis cinerea The impact on growth;

[0021] Figure 6 for Meyerozyma guilliermondii JY19 Botrytis cinerea Mixed inoculation inhibits the effect;

[0022] Figure 7 for Meyerozyma guilliermondii JY19 for ginseng leaves Botrytis cinerea Its preventive effect;

[0023] Figure 8 for Meyerozyma guilliermondii JY19 produces VOCs that affect ginseng leaves. Botrytis cinerea Its preventive effect. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0025] This invention isolated, screened, identified, and obtained a strain of *Gnaphalium affine* JY19 from healthy ginseng leaves grown in forests. Verification showed that this strain exhibited significant antagonistic activity against *Botrytis cinerea*, significantly inhibiting its growth and infection, effectively controlling ginseng gray mold, promoting ginseng growth and development, and ensuring the quality of ginseng and other medicinal plants while increasing their yield. Compared to *Gnaphalium affine* from other sources (such as soil, water, and food), plant-derived *Gnaphalium affine* has undergone long-term "co-evolution" with its host plant, developing specific advantages in "colonization efficiency, functional adaptability, and safety." Specifically, this manifests as stronger colonization ability within the plant, more targeted disease resistance, more suitable growth-promoting and disease-resistant effects, and higher biosafety, without causing environmental pollution or ecological damage.

[0026] On one hand, embodiments of the present invention provide a *Saccharomyces cerevisiae* JY19, whose taxonomic Latin name is... Meyerozyma guilliermondii The sample is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 34980, and the deposit date is June 24, 2025. On the other hand, embodiments of the present invention provide a bacterial agent of *Saccharomyces cerevisiae* JY19 as described above.

[0027] On the other hand, embodiments of the present invention provide cell-free supernatant of *Saccharomyces cerevisiae* JY19 as described in the foregoing embodiments.

[0028] In some embodiments, the preparation step of the cell-free supernatant includes: centrifuging the fermentation broth of *Saccharomyces cerevisiae* JY19 described in the foregoing embodiments, taking the supernatant and filtering it to obtain the cell-free supernatant.

[0029] In some embodiments, the fermentation broth is obtained by culturing *Trichoderma guildrums* JY19. The culture temperature can be 5–35°C, specifically any one or any combination of 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, and 35°C. The culture medium can be a commonly used medium for *Trichoderma guildrums*, including PDA or PDB medium.

[0030] On the other hand, embodiments of the present invention provide volatile organic compounds (VOCs) of *Saccharomyces cerevisiae* JY19 as described in the foregoing embodiments.

[0031] In some embodiments, the metabolites include volatile organic compounds (VOCs).

[0032] In some embodiments, the preparation step of the volatile organic compound includes: inoculating *Saccharomyces giardi* JY19 into a culture medium and culturing it at 5–35°C. Specifically, this temperature can be any one or a range between any two of the following: 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, and 35°C.

[0033] In some embodiments, the culture medium includes PDA culture medium or PDB culture medium.

[0034] On the other hand, embodiments of the present invention provide a biocontrol agent, which includes: the yeast JY19 described in the foregoing embodiments, the bacterial agent described in the foregoing embodiments, the cell-free supernatant described in the foregoing embodiments, or the metabolites described in any of the foregoing embodiments.

[0035] On the other hand, embodiments of the present invention provide the application of *Saccharomyces cerevisiae* JY19, the fungal agent, the cell-free supernatant, the metabolite, or the biocontrol agent as described in the foregoing embodiments in the control of gray mold in medicinal plants.

[0036] In some embodiments, the medicinal plant is selected from any one or more of the following: ginseng, American ginseng, Panax notoginseng, Gastrodia elata, Rehmannia glutinosa, Angelica sinensis, and Codonopsis pilosula.

[0037] The promotion and application of this technology is not only of great significance for promoting the construction of a green disease prevention and control system in the ginseng cultivation industry, but also plays a vital role in the green and high-quality development of the ginseng industry.

[0038] On the other hand, embodiments of the present invention provide the application of *Saccharomyces cerevisiae* JY19, the fungal agent, the cell-free supernatant, the volatile organic compound, or the biocontrol agent as described in the foregoing embodiments in controlling *Botrytis cinerea*. *Botrytis cinerea* is primarily a plant pathogen, with plants as its natural host; it is not a common human pathogen, and normal contact with healthy individuals will not lead to infection. Inhibition of *Botrytis cinerea* is for non-disease treatment or diagnostic purposes.

[0039] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0040] Example 1

[0041] A novel endophytic antagonistic yeast M.guilliermondiiJY19 was isolated from healthy ginseng leaves grown under forest cover at Yunxiu Ginseng Industry Technology Co., Ltd., Dongfeng County, Liaoyuan City, Jilin Province (125°14'23"E, 42°22'40"N, 435m). The antagonistic effect of this strain on the pathogen causing ginseng gray mold was evaluated through confrontation and double-plate culture experiments. B.cinerea The antagonistic ability. Specific methods are as follows:

[0042] (1) M.guilliermondii Isolation and Culture of JY19: Endophytic yeast was isolated from the leaves of healthy forest ginseng. After repeatedly rinsing the leaves with clean water, the leaf surface was disinfected with 75% alcohol for 1 min, followed by rinsing five times with sterile water. The cleaned leaves were drained, chopped, and placed in a sterile mortar with 10 mL of sterile water. The mixture was ground thoroughly for 10 min, and then serially diluted to a specific concentration. , , The homogenate was ground, and 100 µL was spread onto PDA medium. It was incubated in the dark at 25°C for 2–3 days, observing for single colony growth. Colonies of different shapes and colors were selected and streaked onto PDA medium for isolation. Sterilization was performed to obtain stable single colonies. The purified single colonies were then inoculated into PDB medium and incubated at 25°C and 180 r / min with shaking for 24 h until the culture became turbid.

[0043] (2) M.guilliermondii Purification and preservation of JY19: The isolated strain was purified using the streak plating method before identification. A pre-prepared turbid bacterial suspension was taken, and under aseptic conditions, a sterile inoculating loop was used to streak the suspension onto a PDA plate in a zigzag pattern. The remaining suspension was frozen at -80 ℃ for later use. The inoculated PDA plates were then placed in an incubator at 25 ℃ and inverted for 5 days, during which time colony growth and contamination with other microorganisms were observed.

[0044] (3) M.guilliermondii Preliminary morphological identification of JY19: The strain was inoculated onto PDA medium and incubated upside down in a 25°C dark incubator for 2-3 days. After single colonies appeared, the colony texture, shape and size, edge regularity, surface smoothness, presence of raised areas, transparency, colony color, and the color of the medium were observed. Figure 1 As can be seen, the JY19 strain presents as milky white, round colonies with wrinkled edges and a viscous texture.

[0045] (4) M.guilliermondiiMolecular biological identification of JY19: Total DNA extracted from the strain was diluted 200-fold and used as a template for PCR amplification. Universal primers for the fungal internal transcribed spacer (ITS) sequence, ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′), were used to amplify the strain sequence. The 50 μL PCR reaction system consisted of: 4 μL strain DNA, 25 μL 2×Taq MasterMix (GenStar), 1.7 μL each of ITS1 and ITS4, and 17.6 μL dd... PCR reaction conditions: 94℃ pre-denaturation for 2 min, 94℃ denaturation for 30 s, 56℃ annealing for 30 s, 72℃ extension for 1 min, for a total of 30 cycles, with a final extension at 72℃ for 5 min. The obtained PCR products were subjected to 1% agarose gel electrophoresis. The PCR original bacterial solution showing detectable target bands was sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing. The obtained sequences were entered into NCBI and compared and analyzed using BLAST and DNAMAN software. Based on the BLAST alignment results and phylogenetic tree (…),… Figure 2 The yeast strain JY19, isolated from healthy ginseng leaves in a forest, has an ITS sequence (SEQ ID NO:1) that is highly similar to several known strains in the database, especially to... M.guilliermondii It exhibits extremely high sequence consistency. According to BLAST alignment results, JY19 and... M.guilliermondii (Strains such as MZ254922.1 and MK990464.1) share 100% QueryCover, with sequence identity reaching 99.18%–99.67% and an E-value of 0, indicating that the alignment results have extremely high reliability and statistical significance, and can be basically confirmed as strains of the same species or very closely related strains. In the constructed phylogenetic tree, JY19 clusters in... M.guilliermondii The strain JY19 was identified as belonging to the genus *Gnaphalium spp.* and formed a highly supported monophyletic clade with several reference strains (such as EGZ-46, EGZ-61, and KLG-064). This result further validated the conclusions of the BLAST analysis. The clade exhibited a clear topological structure and high Bootstrap support value in the phylogenetic tree, indicating that the clustering relationship is evolutionarily stable and reliable. In conclusion, the strain was ultimately identified as JY19, belonging to the genus *Gnaphalium spp.* Meyerozyma guilliermondii Members of ) will be named M.guilliermondii JY19.

[0046] (5) M.guilliermondii JY19 B.cinerea Determination of direct antagonistic ability: strain JY19 was compared with... B.cinereaConfrontation culture was conducted, and the results showed that strain JY19 was effective against the pathogen. B.cinerea It has a strong inhibitory effect. The specific steps are as follows: Strawberry culture: Transfer strain JY19 to PDB medium and culture at 25℃ and 180 r / min on a shaker for 48 h until the bacterial solution becomes turbid. Mycelial cake preparation: Use a sterile pipette tip with a diameter of 6 mm... B.cinerea Punch a hole at the edge of the colony, remove a 6 mm diameter mycelial cake, and place it in the center of the PDA medium. Inoculate with yeast, taking 10 µL of the already turbid JY19 bacterial suspension and inoculating 2.5 cm away from each side of the mycelial cake. Repeat the treatment three times. Incubate the medium at 25°C for 5 days. Again, use a 6 mm diameter sterile pipette tip... B.cinerea Perforations were made at the edge of the colonies to obtain mycelial cakes with a diameter of 6 mm, and these cakes were placed in the center of PDA medium. A sterile inoculation loop was used to dip into JY19 bacterial suspension and streak a line 1 cm from the mycelial cake to form a yeast band. The bands were then incubated at 25°C for 5 days. In the direct inoculation experiment, after 5 days, the colony diameter in the JY19 treatment group was 0.59 ± 0.06 cm, while that in the control group was 8.47 ± 0.06 cm, with an inhibition rate of 93%. P <0.05); In the yeast streak inhibition test, 5 days after inoculation, the colony diameter in the JY19 treatment group was 0.28 ± 0.16 cm, while that in the control group was 8.40 ± 0.17 cm, with an inhibition rate of 95% ( P <0.05). Observed M.guilliermondii JY19 B.cinerea It has a direct antagonistic inhibitory effect (see Figure 3 ).

[0047] (6) M.guilliermondii JY19 cell-free supernatant B.cinerea Antagonistic effect determination: Strain JY19 was transferred to PDB medium and cultured at 25℃ and 180 r / min on a shaker for 48 h until the culture became turbid. The fermentation broth was collected and centrifuged at 12000 rpm for 15 min to remove the cells. The supernatant was filtered through a 0.22 μm filter membrane to obtain cell-free supernatant (CFS). 10 ml of CFS was mixed thoroughly with an equal volume of PDB medium melted and cooled to approximately 50℃ at a 1:1 volume ratio. The mixture was poured into plates to prepare the treatment group. Simultaneously, PDB plates without CFS were prepared as the control group. A sterile pipette tip with a diameter of 6 mm was used. B.cinerea Perforations were made at the edge of the colonies, and a 6 mm diameter mycelial cake was taken and placed in the center of the above-mentioned culture medium. The culture was incubated at 25 ℃ for 5 days. Five days after inoculation, the colony diameter of the control group (8.30 ± 0.10 cm) was significantly larger than that of the JY19 treatment group (1.05 ± 0.07 cm).P <0.05). Observed M. guilliermondii JY19 cell-free supernatant B.cinerea It has a significant antagonistic effect. Figure 4 ).

[0048] (7) M.guilliermondii JY19 produces volatile organic compounds (VOCs) and has a significant impact on... B.cinerea Determination of antagonistic effect: To explore whether VOCs produced by strain JY19 can be directly inhibited B.cinerea The growth of JY19 and B.cinerea Inoculate onto PDA medium as follows: Inoculate 6 mm diameter cells into the lower layer of PDA medium. B.cinerea The mycelial cake was then evenly spread with 100 µL of 1× [agar / carbohydrate] onto the upper PDA medium. CFU / mL JY19 bacterial suspension was spread onto PDA plates containing an equal volume of sterile water as a control. The two plates were then inverted and sealed with sealing film and Vaseline. The culture medium was incubated at 25℃ for 5 days. On day 5, the control group colonies almost covered the entire plate (6.67 ± 0.15 cm), while the VOCs-treated group had colonies only 0.13 ± 0.02 cm in diameter. P <0.05), and its inhibition rate was calculated to be as high as 98%. It was observed that VOCs produced by strain JY19 could be directly inhibited. B.cinerea growth ( Figure 5 ).

[0049] (8) M.guilliermondii JY19 produces volatile organic compounds (VOCs) and has a significant impact on... B.cinerea Effects on spore germination: Using the double-plate inverted culture method described above, the effects of VOCs produced by strain JY19 on spore germination were assessed. B.cinerea It has an inhibitory effect on spore germination. JY19 and... B.cinerea The spore suspension was inoculated onto PDA medium as follows: 100 µL of 1× spore suspension was evenly spread onto the upper layer of PDA medium. JY19 bacterial suspension at CFU / mL was prepared, and an equal volume of sterile water was spread on a PDA plate as a control. Sterile cellophane was placed on the lower PDA culture dish, and 20 µL of 1× CFU / mL bacterial suspension was spread on top. CFU / mL B.cinereaSpore suspension. Two plates were inverted and sealed with sealing film and Vaseline. Observations were performed using an optical microscope at 3, 6, 9, and 12 h, and analyzed using ScopeImage 9.0 software. Spore germination rate and the number of germinating spores were recorded periodically, with 100 spores observed per plate. A conidium was considered to have germinated when its germ tube length reached or exceeded half the diameter of the conidium. Each group had three replicates. The spore germination inhibition rate was calculated using the following formula: Conidium germination inhibition rate (%) = (Gc - Gt) / Gc × 100%. Where Gc is the germination rate of the control group, and Gt is the germination rate of the treatment group. In the control group, the spore germination rate increased significantly over time: 11.5 ± 0.7% at 3 h, 50.6 ± 0.7% at 6 h, 85.3 ± 1.3% at 9 h, and 96.4 ± 0.7% at 12 h. In the VOCs treatment group, no spore germination was observed from 0 to 6 h (0%), the germination rate was only 2.6 ± 0.1% at 9 h, and only 6.3 ± 0.1% at 12 h, all significantly lower than the control group. P <0.05). Calculations showed that the spore germination inhibition rate was 90.2% after 12 h of treatment. VOCs produced by strain JY19 were observed to significantly inhibit spore germination. B.cinerea Spore germination.

[0050] Table 1 Meyerozyma guilliermondii JY19 VOCs Botrytis cinerea Effects of spore germination

[0051]

[0052] Note: Means with different letters (a~g) showed significant differences in multiple comparison analyses. P <0.05); there was no significant difference between values ​​with the same letter ( P ≥0.05).

[0053] (9) M. guilliermondii JY19 B. cinerea The inhibitory effect of mixed inoculation on conidial germination: B.cinerea Spore suspension (1× CFU / mL) and JY19 bacterial culture (1× A 1:1 volume ratio of CFU / mL was used to mix the spores of *Botrytis cinerea* and spores, and 20 μL of the mixture was added dropwise to PDA medium. The control group spore suspension was mixed with an equal volume of sterile water. The PDA medium was incubated at 25℃ for 4 days. The spore germination and subsequent hyphal growth of *Botrytis cinerea* were observed. After 4 days of incubation, the hyphae in the control group fully expanded, with a colony diameter reaching 8.43 ± 0.04 cm; while in the treatment group, only the growth of JY19 colonies was observed, with no other colonies. B. cinerea Mycelial growth. The results indicate... M. guilliermondiiJY19 B.cinerea Mixed inoculation of conidial germination has a strong inhibitory effect. Figure 6 ).

[0054] (10) M.guilliermondii JY19 B.cinerea Verification of the preventive effect against gray mold in ginseng (leaf inoculation method): Healthy ginseng plants were selected, and the upper and lower surfaces of the leaves were evenly sprayed with bacterial solution of strain JY19. The spraying amount was approximately 1 mL per plant, and the bacterial solution concentration was 1× CFU / mL, while the control group was sprayed with an equal volume of sterile PDB medium. After spraying, the cells were incubated under standard conditions for 24 h to promote colonization of strain JY19 on the leaf surface. A sterile pipette tip with a diameter of 6 mm was used. B. dinner Puncture holes along the edge of the colony to obtain mycelial cakes with a diameter of 6 mm. Carefully attach these cakes to the center of the upper surface of ginseng leaves as inoculation for pathogen control. Immediately after inoculation, cover the leaves with a transparent plastic cover to create a high-humidity environment for 8 hours to promote growth. B. dinner Successful infection was achieved, after which the membrane was removed and routine culture management resumed. Three days post-inoculation, the occurrence of disease on ginseng leaves was recorded to systematically evaluate the effects of JY19 on... B. dinner The control effect of bacterial infection on ginseng gray mold. Healthy ginseng leaves were selected, and without foliar spraying of bacterial solution, they were placed in a transparent, sealed incubator as a VOCs treatment. 100 µL of 1× [a specific type of bacterial solution] was evenly coated inside the container. PDA medium containing CFU / mL JY19 bacterial suspension was used as the VOCs release source, while the control group contained an equal volume of sterile medium. VOCs were pretreated for 3 days, followed by the release of VOCs through a 6 mm diameter sterile punch. B. dinner Mycelial cakes were collected from the edge of the colony and applied to the center of the upper surface of ginseng leaves for pathogen inoculation. Immediately after inoculation, the leaves were covered with a transparent plastic cover or kept in a sealed environment for 8 hours to create high humidity conditions to promote infection, after which normal culture was resumed. The disease severity of each leaf was assessed 3 days post-inoculation, and the effects of JY19 VOCs on the pathogen were systematically evaluated. B. dinner Antagonistic efficacy against ginseng gray mold caused by infection. Observations showed that both JY19 bacterial suspension treatment and VOCs treatment could significantly reduce the relative lesion area of ​​gray mold ( Figure 7 and Figure 8 ).

[0055] The sequence of SEQ ID NO:1 is as follows:

[0056] .

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A type of *Saccharomyces cerevisiae* JY19, characterized in that, Its taxonomic Latin name is Meyerozyma guilliermondii It is deposited at the China General Microbiological Culture Collection Center, with accession number CGMCC No. 34980.

2. The yeast agent of *Saccharomyces cerevisiae* JY19 as described in claim 1.

3. The cell-free supernatant of *Saccharomyces cerevisiae* JY19 as described in claim 1.

4. A biocontrol agent, characterized in that, It includes: The *Saccharomyces cerevisiae* JY19 as described in claim 1, the inoculum as described in claim 2, or the cell-free supernatant as described in claim 3.

5. The application of the yeast JY19 of claim 1, the inoculum of claim 2, the cell-free supernatant of claim 3, or the biocontrol agent of claim 4 in the control of gray mold in medicinal plants; The medicinal plants are selected from any one or more of the following: ginseng, American ginseng, Panax notoginseng, Angelica sinensis, and Codonopsis pilosula.

6. The *Saccharomyces cerevisiae* JY19 as described in claim 1, the inoculum as described in claim 2, the cell-free supernatant as described in claim 3, or the biocontrol agent as described in claim 4 in controlling *Botrytis cinerea* (…). Botrytis cinerea Applications in ).

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