CN110684678B

CN110684678B - Meiji saccharomyces cerevisiae strain for preventing and treating post-harvest gray spot of loquat and application thereof

Info

Publication number: CN110684678B
Application number: CN201911009506.8A
Authority: CN
Inventors: 孙卫红; 杨慧慧; 王玲; 赵一繁; 李胜杰; 毋宁宁; 高兴彪
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2019-10-23
Filing date: 2019-10-23
Publication date: 2022-06-21
Anticipated expiration: 2039-10-23
Also published as: CN110684678A

Abstract

The invention discloses a meiji yeast strain for preventing and treating post-harvest gray spot of loquat and application thereof, and belongs to the technical field of biological prevention and treatment of fruit after-harvest. The biocontrol yeast is identified as Meiji yeast (Metschnikowia pulcherrima) with the collection number of: CCTCC M2019256. Firstly, preparing a polyspora weberiana P2 conidium suspension and a meiji yeast E1 suspension for later use; then drilling a hole (3mm multiplied by 3mm) at the equator part of the loquat fruit, adding E1 bacterial suspension, and adding P2 conidium suspension after 2 h; after drying, placing the mixture into a plastic basket, sealing the plastic basket by using a preservative film, and storing the plastic basket at room temperature. The morbidity and the decay direct decline of the loquat gray leaf spot treated by the bacterial suspension are both obviously reduced. Therefore, the meiji yeast can be used for preventing and treating the ashmeadow disease of the picked loquat and reducing the harm to human health and the pollution to the environment caused by the use of chemical sterilization.

Description

Meiji saccharomyces cerevisiae strain for preventing and treating post-harvest gray spot of loquat and application thereof

Technical Field

The invention relates to a Metschnikowia pulcherrima E1 strain, which can control the gray leaf spot of picked loquat and belongs to the technical field of biological control of picked fruits.

Background

Loquat (Eriobotrya japonica, iandl) belongs to Rosaceae (Rosaceae) and Eriobotrya (Eriobotrya), is originally produced in southeast China, and the ripe loquat fruits are sweet and rich in nutrients, rich in fructose, glucose, carotene, vitamin A, B, C and other components, have the effects of moistening lung, relieving cough and quenching thirst and are well received by consumers. At present, the planting area and the yield of the loquats in China are both rapidly improved, the production scale accounts for more than 80 percent of the loquats in the world, and the loquats occupy absolute advantages internationally, thereby becoming one of the fruits with international market competitiveness in China. Because the loquat has thin peel and tender and succulent pulp, the loquat is easy to generate mechanical damage and is easy to rot, so that the storage period of the picked fruits is shorter. Researches show that the infection of pathogenic microorganisms is the main cause of loquat rot, and the loquat post-harvest infectious diseases comprise anthracnose, gray spot, black spot, gray mold and the like. The loquat leaf spot can damage branches, leaves, flowers and fruits of the loquat, the loquat fruits can be damaged from young fruits to mature stages, and the loquat fruits can soften and rot the fruits in severe cases, and the diseases are caused by the pestalotiopsis fungi.

The common methods for controlling the diseases of the loquat after picking mainly comprise a physical method and a chemical method. The physical method mainly comprises heat treatment, low-temperature storage, air-conditioned storage, low-pressure storage, irradiation treatment and the like. Although the physical method has good effect on preventing and treating postharvest diseases and can effectively reduce the rottenness of postharvest fruits, the method cannot be widely applied to production practice due to complex operation, high technical requirements and high cost. The chemical method is to use chemical bactericide for treatment, mainly comprising chlorothalonil, carbendazim, application and protection, and the like, and has the characteristics of wide bactericidal spectrum, high efficiency, low cost, simple operation and the like, but the chemical agent is easy to cause environmental pollution and harm the health of people and livestock when being used excessively, and pathogenic bacteria can generate drug resistance. In recent years, with the improvement of economic development and consumption level, people have strengthened consciousness on food safety and environmental protection, so that a new green, safe and efficient method for preventing and treating loquat postharvest diseases, which can replace chemical bactericides, is urgently needed to be searched.

Biological control is a method for controlling postharvest diseases of fruits by using antagonistic microorganisms harmless to human bodies, has the characteristics of high efficiency, safety, energy conservation, environmental protection and the like, and is concerned by more and more researchers. In recent years, the biological control bacteria which have been researched mainly comprise bacteria, moulds, yeasts and the like, wherein antagonistic yeasts become main research objects due to the advantages of simple nutritional requirements, inheritance, rapid propagation, strong stress resistance and the like. At present, many researches on the application of antagonistic yeast to the postharvest diseases of fruits and vegetables are carried out at home and abroad, more researches on the application of the antagonistic yeast to anthracnose are carried out in the control of the postharvest diseases of the loquats, and few researches on the gray leaf spot disease of another main disease of the picked loquats are carried out, so that the researches on the application of the antagonistic yeast to the control of the gray leaf spot disease of the picked loquats are of great significance for searching for an effective preservation method of the picked loquats.

The yeast meigmuii (Metschnikowia pulcherrima) is ubiquitous in nature, being mainly present on the surface and flowers of some fruits. The strain has the advantages of high growth speed, simple nutritional requirement and strong stress resistance. At present, the Meiji Meiqi microzyme is reported in the domestic literature to be used for preventing and treating the penicilliosis of winter jujube after picking, the brown rot of peach after picking and the gray mold of apple after picking, but no report is available for preventing and treating the gray spot of loquat.

Disclosure of Invention

Aiming at the problems of high cost, high chemical pesticide residue and the like of fungus disease control after loquat picking in the current agricultural production, the invention separates and identifies a eriobotrya japonica gray spot dominant pathogenic bacterium in Zhenjiang area from the rotten loquat after picking, and simultaneously provides a Metschnikowia pulcherrima (Metschnikowia pulcherrima) E1 separated from loquat branches and leaves.

The technical scheme adopted by the invention

The pathogenic bacteria of loquat gray spot disease for antagonistic yeast screening provided by the invention are separated from rotten loquats collected from organic orchards in Yangjiang province, Zhenjiang province, and the pathogenic fungi are identified as Pestalotiopsis virginiae (Pestalotiopsis virginiae) through morphological observation and sequence analysis of 5.8S rDNA-ITS (internal transcribed spacer region) of the pathogenic fungi.

The preservation information for this pathogen is as follows: the preservation name is: pestalotiopsis victoria P2(Pestalotiopsis vismaie P2); the preservation number is CCTCC NO of M2019257; the preservation unit: china Center for Type Culture Collection (CCTCC); and (4) storage address: wuhan university in Wuhan, China; the preservation date is as follows: 15/4/2019; the suggested classification is named: pestalotiopsis vismodie P2P 2.

The yeast strain for preventing and treating the picked loquat leaf spot is obtained by separating loquat branches and leaves in an organic orchard in Yangzhong of Zhenjiang of Jiangsu province, and is identified as Metschnikowia pulcherrima through morphological observation, physiological and biochemical characteristics and 5.8S rDNA-ITS (internal transcribed spacer region) sequence analysis.

The preservation information of the yeast is as follows: the Meiji Meiqi yeast E1(Metschnikowia pulcherrima E1) has been preserved in China Center for Type Culture Collection (CCTCC) in 2019, 4 and 15 days, and the preservation address is Wuhan university, Wuhan, China, with the preservation number of CCTCC NO: M2019256, and the suggested classification is named as: the yeast Saccharomyces meijimeiqi E1 Metschnikowia pulcherrima E1.

The method for preventing and treating the post-harvest gray leaf spot of the loquat by using the Metschnikowia pulcherrima E1 is carried out according to the following steps: firstly, streaking and inoculating meiji yeasts to an NYDA culture medium, culturing at 28 ℃ for 2-3 days for activation, then inoculating to an NYDB culture medium, performing shake culture for 18-24 hours to obtain a seed solution, inoculating the seed solution into the NYDB culture medium with the inoculum size of 5%, performing shake culture at 28 ℃ for 20-24 hours, centrifuging to obtain bacterial sludge, diluting with sterile water, and preparing into 1 × 10⁸cell/mL of bacterial suspension for later use; drilling a hole (3mm multiplied by 3mm) at the equator part of the loquat fruit, adding 20 mu L of the bacterial suspension, and adding the Wasmei pestalotiopsis P2 conidium suspension after 2 h; after drying, placing the mixture into a plastic basket, sealing the plastic basket by using a preservative film, and storing the plastic basket at room temperature.

Wherein the NYDA culture medium comprises the following components: 8g of beef extract, 5g of yeast extract, 10g of glucose and 20g of agar powder, supplementing the beef extract with distilled water to 1000mL, naturally adjusting the pH value, and sterilizing at 121 ℃ for 20 min.

Wherein the NYDB culture medium comprises the following components: 8g of beef extract, 5g of yeast extract and 10g of glucose, supplementing to 1000mL by distilled water, naturally adjusting pH, and sterilizing at 121 ℃ for 20 min.

The invention has the advantages that:

(1) the pathogenic bacterium, vistaspora vispora (Pestalotiopsis vismia) P2, of the loquat leaf spot after picking is the dominant pathogenic bacterium screened by the laboratory in the Jiangsu Zhenjiang area, and the pathogenic effect is strong.

(2) The Metschnikowia pulcherrima E1 used in the invention is screened by the laboratory, has strong antagonistic effect, and is proved to be a practical nontoxic class by a mouse acute toxicity test.

(3) The meiji yeast (Metschnikowia pulcherrima) E1 used in the invention can obviously inhibit the occurrence of the grey spot disease of the picked loquat fruits, reduce the loss caused by the diseases of the picked loquat fruits and has certain commercial value.

(4) The meiji yeast (Metschnikowia pulcherrima) E1 used in the invention has no report of application in loquat at present, and has certain innovation.

(5) The Metschnikowia pulcherrima E1 can replace chemical bactericides to prevent and control postharvest diseases of fruits, and has remarkable economic and social benefits.

The present invention will be described in more detail by the following examples, which are illustrative only, and the present invention is not limited by these examples.

Drawings

FIG. 1 shows the morphological characteristics of Pestalotiopsis victoria P2; in the figure, A: colony morphology on PDA; b: the back of the colony on the PDA; c: hyphae; d: conidia.

FIG. 2 is an evolutionary tree constructed from the 5.8S rDNA-ITS sequence of Pestalotiopsis victoria P2.

FIG. 3 shows the morphological characteristics of Saccharomyces meibomiae (Metschnikowia pulcherrima) E1; FIG. A: colony morphology on NYDA; and B: cell morphology.

FIG. 4 is a phylogenetic tree constructed from the 5.8S rDNA-ITS sequence of Saccharomyces meiji (Metschnikowia pulcherrima) E1.

FIG. 5 shows the experimental design of the confronting relationship between Saccharomyces meisterii (Metschnikowia pulcherrima) E1 and the plate of pathogenic bacterium P2.

FIG. 6 shows the effect of Saccharomyces meisterii (Metschnikowia pulcherrima) E1 on the rotting rate of loquat fruit gray spot. Note: the control group was treated with distilled water; the experimental group is treated by 1X 108cells/mL of Meiji yeast E1 bacterial suspension.

Detailed Description

Example 1: isolation, purification and characterization of pathogenic bacteria

1.1 isolation and purification of pathogenic bacteria

Organic loquat fruits of Bahong variety with consistent maturity and size and no plant diseases and insect pests are picked from 'cloud standard orchards' in Zhenjiang city of Jiangsu province, transported back to a laboratory, placed in a plastic basket sterilized by sodium hypochlorite, sealed by a preservative film, stored at room temperature for about 15 days, picked with obvious diseases, and subjected to pathogenic bacteria separation by a tissue separation method. Tissue blocks of about 5mm in size were cut from the rotten part with a sterile scalpel, sterilized with 75% ethanol for several seconds, rinsed with sterile water for 3 times, drained, placed on a PDA medium, and cultured in a constant temperature incubator at 28 ℃. After the colonies grow out, picking hyphae at the edges of the colonies, streaking and separating the hyphae on a PDA (personal digital assistant) flat plate, culturing the hyphae at the temperature of 28 ℃ for 3-5 days, and purifying the obtained colonies for multiple times to obtain single colonies. And (4) placing the separated and purified strains in a refrigerator at 4 ℃ for short-term storage for later use.

1.2 detection of pathogenicity of pathogenic bacteria

Verifying by using the Koehler's rule, and selecting healthy loquat fruits for carrying out a back grafting experiment. Culturing the separated and purified pathogenic bacteria on a PDA (personal digital assistant) plate at 28 ℃ for 7-10 days, scraping black conidial on the surface of hyphae by using an aseptic inoculating loop, suspending the black conidial in sterile water, and adjusting the concentration of conidia to be 1 multiplied by 10⁵spores/mL for later use; washing healthy loquat fruits with clear water, soaking and disinfecting the fruits with 0.1% sodium hypochlorite solution for 10min, washing the fruits with clear water for two or three times, and naturally drying the fruits. Cutting 3mm deep wound on equator of fruit with sterilized perforator, and collecting 20 μ l of the cut with concentration of 1 × 10⁵Inoculating the sporophyte/mL conidium suspension to the wound, putting the wound into a plastic basket to be placed in order, sealing the wound with a preservative film, culturing the wound at room temperature for 3-5 days, observing the morbidity condition and the lesion diameter of the loquat fruits every day, and observing pathogenic bacteria by taking inoculated sterile water as a contrastThe magnitude of the pathogenic force of (2). And then selecting the obviously diseased fruits to separate and identify the pathogenic bacteria again, judging whether the shapes of the fruits are consistent with the shapes of the connected pathogenic bacteria, and if so, determining the picked pathogenic bacteria of the loquats.

The test result shows that pathogenic bacteria with the same form as the original inoculated pathogenic bacteria are separated again from the diseased part of the loquat, and the strain P2 is the picked pathogenic bacteria of the loquat. After the loquat wound is inoculated for 5 days, the loquat fruits are completely attacked by the pathogenic bacteria treatment group, the disease spot diameter is 1.59cm, the rotting rate of the loquat fruits of the sterile water treatment group is only 8.89%, the disease spot diameter is 0.93cm, the disease rate and the disease spot diameter of the loquat fruits of the pathogenic bacteria treatment group are both obviously lower than those of a control group (P <0.05), and the pathogenic effect of the Wasmei Pantoea pilifera is strong.

1.3 morphological identification

And (3) selecting hyphae of the separated and purified strain P2, inoculating the hyphae into a PDA culture medium, culturing for 5-10 days, observing colony morphology on the culture medium, selecting hyphae and conidia, and observing the hyphae and the conidia, wherein the morphological characteristics are shown in figure 1. The pathogenic strain P2 is cultured at 28 deg.C, its front side is white villus and its back side is orange yellow on PDA culture medium, and black conidium disc visible to naked eye appears on the surface of hypha at the late stage of culture. The conidia of strain P2 were observed by light microscopy to consist of 5 cells, fusiform or spindle-shaped, straight or slightly curved. The middle trichromatic cells are olive-colored and are nearly brown; the top end is a conical colorless cell, and 2-3 filaments are attached to the top end; the basal part is a triangular pyramid colorless cell and has 1 middle stem.

1.4 molecular biological identification

The 5.8S rDNA-ITS region sequence of the separated and screened pathogenic bacterium strain P2 is analyzed, and the sequence is searched in GenBank to determine that the strain is the Pestalotiopsis vismodia (Pestalotiopsis vismodia). According to the retrieved homologous strains, a biological evolutionary relationship tree was constructed by using the Mege5.1 program of DNAStar software as shown in FIG. 2.

The preservation information for this pathogen is as follows: the preservation name is: pestalotiopsis victoria P2(Pestalotiopsis vismaie P2); the preservation number is CCTCC NO of M2019257; the preservation unit: china Center for Type Culture Collection (CCTCC); and (4) storage address: wuhan university in Wuhan, China; the preservation date is as follows: 15/4/2019; the proposed classification is named: pestalotiopsis vismodie P2P 2.

Example 2: isolation screening and identification of antagonistic yeast strains

2.1 isolation and purification of antagonistic yeasts

A loquat branch and leaf sample is collected from a cloud standard orchard in Zhenjiang, Jiangsu province, and Yangtze City, cut into pieces with the size of 1cm, put into a conical flask (250mL) containing 90mLPDB culture medium, added with a few drops of streptomycin sulfate solution (about 3mg), and cultured for 20h at the constant temperature of 28 ℃ and 180rpm by shaking. Diluting the bacterial liquid to 10 degrees with sterile water by adopting a tenfold gradient dilution method^-4、10^-5、10^-6And sucking 100 mu L of the diluted solution, coating the diluted solution on a Bengal red culture medium plate, and culturing for 2-3 days at a constant temperature of 28 ℃. And observing colony morphology of each yeast strain, and then selecting single colonies with different culture characteristics to carry out purification culture on NYDA medium plates. And (4) placing the separated and purified strains in a refrigerator at 4 ℃ for short-term storage for later use.

2.2 screening of antagonistic yeasts

In vitro primary screening: in the first step, the isolated yeast was flash streaked onto 1X 10 yeast coated with 100. mu.L⁵And (3) culturing the sporophyte suspension of the pestalotiopsis virescens/mL on a PDA (personal digital assistant) flat plate at 28 ℃ for 4-5 days, observing the growth condition of hyphae on the flat plate, and selecting the saccharomycetes with the effect of inhibiting the growth of pathogenic bacteria hyphae for next screening. Secondly, screening by adopting a flat plate opposing method, absorbing 1 multiplied by 10⁸100 mu L of cfu/mL yeast suspension is coated on one side of an NYDA plate, then pathogenic bacteria mycelium blocks with the diameter of 6mm are inoculated at the positions of the other side, which are equidistant to the yeast and the edge of the plate, the mixture is cultured for 2-3 d at the temperature of 28 ℃, the inhibition condition of antagonistic yeast on the growth of pathogenic bacteria is observed, and the yeast with good biocontrol effect is selected for in vivo screening.

Re-screening in vivo: washing loquat fruits with uniform size and no mechanical damage with clear water, soaking and sterilizing the loquat fruits with 0.1% sodium hypochlorite solution for 10min, washing the loquat fruits with clear water for two or three times, and naturally drying the loquat fruits. Punching a hole (3mm × 3mm) at equator of fructus Eriobotryae with sterilized puncher, adding 20 μ L1 to wound10⁸cfu/mL yeast suspension, standing for 2h, adding 20 μ L1 × 10⁵spore suspension of the Websmes/mL pestalotiopsis pilosellosis, and sterile water is used for replacing yeast suspension as a control. Putting the loquat fruits in a plastic basket, putting the loquat fruits in order, sealing the loquat fruits by using a preservative film, storing the loquat fruits at room temperature, observing the rotting condition of the loquat fruits after 5 days, and finally screening to obtain a strain E1 with the best antagonistic effect.

2.3 morphological characteristics

The morphological characteristic result is shown in figure 3, after the bacterial strain E1 is cultured on NYDA culture medium at 28 ℃ for 2 days, the bacterial colony is round, small, cream, opaque, neat in edge, moist and smooth in surface, easy to pick up, capable of generating red pigment, reddish brown in reverse and rich in fermentation smell. When cultured in NYDB medium, the thallus is turbid, a large amount of precipitate is generated, and the thallus has aromatic flavor. Cells are observed by a microscope to be spherical or nearly spherical, and are germinated on one side or multiple sides.

2.4 physiological and Biochemical characteristics

The strain E1 can ferment and utilize glucose, but cannot ferment sucrose, maltose, lactose, raffinose and trehalose; glucose, sucrose, maltose, cellobiose, trehalose, mannan, xylitol, sorbitol, succinic acid, ethanol, glycerol, but not arabinose, raffinose, lactose and erythritol.

2.5 molecular biology characterization

The 5.8S rDNA-ITS region sequence of the yeast strain E1 obtained by screening was analyzed, and the sequence was searched in GenBank and determined to be Metschnikowia pulcherrima. Based on the retrieved homologous strains, a tree of biological evolutionary relationships was constructed using the Mege5.1 program of DNAStar software, as shown in FIG. 4. The strain is stored in China Center for Type Culture Collection (CCTCC) 4-15.2019, the preservation address is Wuhan university in Wuhan, China, the preservation number is CCTCC NO: M2019256, and the suggested classification name is Meiji Meiqi yeast E1 Metschnikowia pulcherrima E1.

Example 3: safety study on Saccharomyces meijiensis (Metschnikowia pulcherrima) E1

The tested animal species is ICR mice, provided by the experimental animal center of Jiangsu university. 40 clean-grade mice with the weight of 18-22 g are selected, and the number of the mice is half that of the mice. The test group is 10 male and female mice respectively, and the maximum limit method is adopted according to the national standard, and the test dose is 10000 mg/kg. Performing oral gavage according to a test of 0.2mL/10g body weight for 14 d; the control group of male and female mice had 10 mice each, and the yeast suspension was replaced with sterile water for intragastric administration. Throughout the experiment, the mice were observed daily for activity, feeding, weight change and whether intoxication or death occurred.

According to the above test procedure, the results of the test for the safety of Metschnikowia pulcherrima E1 were counted as follows: none of the mice 14d inoculated with sterile water and E1 bacteria of Metschnikowia pulcherrima died. And as can be seen from table 1, there is no significant difference in average weight gain between the male and female mice in the experimental group and the control group, and LD₅₀The values are all more than 10000mg/kg of body weight, and according to the acute toxicity grading standard, the Meiji yeast (Metschnikowia pulcherrima) E1 belongs to safe and nontoxic yeast.

TABLE 1 acute oral toxicity test results of Metronikowia pulcherrima (Metschnikowia) E1

Example 4: inhibitory Effect of Metschnikowia pulcherrima E1 on pathogenic bacterium P2

The plate confrontation method was used to study the inhibitory effect of the Metschnikowia sp E1 on pathogenic bacteria. Firstly inoculating yeast E1 into an NYDB culture medium, carrying out shake-flask culture for 18-24 h to obtain a seed solution, then inoculating the seed solution into the NYDB culture medium with the inoculation amount of 5%, carrying out shake-flask culture at 28 ℃ for 20-24 h, centrifugally collecting thalli, suspending the thalli by using sterile water, and adjusting the concentration to 1 x 10⁸cells/mL for use; inoculating pathogenic fungus, namely, the polyspora weberiana on an NYDA culture medium plate, and culturing for 7-10 days at 28 ℃ for later use; the PDA plates were back-plated according to the method shown in FIG. 5Dividing the surface into three parts, marking, coating 50 μ L yeast suspension on the right side of PDA, and culturing in 28 deg.C incubator for 2 d; then, inoculating hypha blocks of pathogenic bacteria P2 with the diameter of 6mm into the left side of the left side; when the hyphae of the pathogenic bacteria P2 grow to the edge of the plate, the lengths of the hyphae on the left and right sides of the pathogenic bacteria are observed and measured, 3 of the hyphae are treated in each group in parallel, and the test is repeated for 2 times.

The results of the plate confrontation test are shown in table 2, the meiji yeast E1 can obviously inhibit the hypha growth of pathogenic bacteria, namely, the polyspora faciopneumoniae, the length (2.88cm) of the hypha on the left side of the pathogenic bacteria is obviously greater than the length (2.05cm) of the hypha on the right side (P is less than 0.05), and the right side yeast is not contacted with the pathogenic bacteria, so that the antagonistic yeast E1 can secrete some antibacterial substances to inhibit the growth of the hypha of the pathogenic bacteria, thereby playing a biological control role.

TABLE 2 influence of Metrifuga sp E1 on growth of Descemet polyspora

Example 4: control effect of Metschnikowia pulcherrima E1 on loquat gray leaf spot

Inoculating Metschnikowia pulcherrima E1 in NYDB culture medium, shake-culturing for 18-24 h to obtain seed solution, inoculating the seed solution into NYDB culture medium at 5%, shake-culturing for 20-24 h at 28 deg.C, centrifuging to collect thallus, suspending with sterile water, and adjusting concentration to 1 × 10⁸cells/mL for use; inoculating Petasites hybridus on PDA culture medium, culturing at 28 deg.C for 7-10 days, and preparing with sterile water to concentration of 1 × 10⁵Conidium suspension of spores/mL for use.

Selecting loquat fruits with uniform size and no mechanical damage, washing the loquat fruits clean with clear water, soaking and disinfecting the loquat fruits for 10min by using a 0.1% sodium hypochlorite solution, washing the loquat fruits twice with clear water, and naturally airing the loquat fruits. Punching a hole (3mm × 3mm) at the equator of the loquat fruit with a sterilized punch, and adding 20 μ L of 1 × 10⁸cfu/mL yeast suspension, standing for 2h, adding 20. mu.L 1X 10⁵spore suspension of the Websmes/mL pestalotiopsis pilosellosis, and sterile water is used for replacing yeast suspension as a control. Putting the loquat fruits in a plastic basket in order, sealing the loquat fruits by using a preservative film, storing the loquat fruits at room temperature, observing and recording the rotting rate and the disease spot diameter of the loquat fruits after 5 days to evaluate the inhibiting effect of the Meiji Meiqi yeast E1 on the picked gray spot of the loquat fruits, wherein the rotting condition of the loquat fruits is shown in figure 6.

The formula for the incidence is as follows:

incidence (%) of disease (%) fruit/total number of fruits affected × 100%

As shown in Table 3, the loquat fruits of the control group 5d were all attacked, the disease spot diameter was 1.59cm, while the loquat fruits of the E1-treated group of Metschnikowia pulcherrima had the disease incidence of only 22.73% and the disease spot diameter was 0.95cm, and both the disease incidence and the disease spot diameter of the fruits of the treated group were significantly lower than those of the control group (P < 0.05). Therefore, the Metschnikowia pulcherrima E1 can effectively control the picked gray spot of the loquat caused by the pestalotiopsis virginiana at room temperature, can be used for storage and preservation of the loquat fruits, and is worthy of further research and popularization.

TABLE 3 influence of M.meiji E1 on the incidence and lesion diameter of loquat gray leaf spot

Claims

1. Pathogenic fungus of wassmei pestalotiopsis of loquat postharvest gray spotPestalotiopsis vismiae) The strain P2 has a preservation number of CCTCC NO: M2019257.

2. Meiji meiqi yeast (for preventing and treating loquat postharvest gray leaf spot disease)Metschnikowia pulcherrima) The strain E1 has a preservation number of CCTCC NO: M2019256.

3. The use of the yeast meiji according to claim 2, characterized in that it is used for controlling the post-harvest gray spot of loquat or for storage and freshness preservation of loquat fruits.