Litchi endogenous polypeptide and application thereof in controlling plant diseases

Abstract

The invention provides an effective and safe litchi endogenous polypeptide and application thereof in controlling plant diseases. The amino acid sequence of the litchi endogenous polypeptide P2 is as shown in SEQ ID NO. 1. After litchi is treated by the litchi endogenous polypeptide P2, the resistance of litchi fruits to peronophythora litchii can be improved. Therefore, the litchi endogenous polypeptide P2 can be used for preparing a novel antifungal disease preservative and a plant disease-resistant inducer, and is applied to the field of prevention and control of plant fungal diseases.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biotechnology, and relates to a litchi endogenous polypeptide and application thereof, in particular to a litchi endogenous polypeptide and application thereof in controlling plant diseases. BACKGROUND

[0002] Litchi Peronophythora disease is one of the important fungal diseases of litchi, which leads to significant decline in pre-harvest and post-harvest nutrition and quality of litchi, and causes significant economic losses. Due to the lack of effective control methods, litchi Peronophythora disease has caused great difficulties to the litchi industry in China, and has gradually become one of the main diseases of litchi. Peronophythora litchii is one of the main pathogenic fungi causing litchi Peronophythora disease. At present, chemical agents are mainly used for prevention and control, which has a certain impact on fruits, and is not conducive to the health of consumers; and drug resistance is easy to occur. Therefore, screening of green fungicides harmless to human body, effective and safe to improve fruit resistance and control disease occurrence has great significance for maintaining the quality of litchi and prolonging the storage period.

[0003] Plant endogenous polypeptide is a new type of plant growth regulator, and related researches are mainly concentrated in the model plant Arabidopsis thaliana. How the endogenous polypeptide in other species functions, especially the role of litchi endogenous polypeptide in controlling postharvest diseases of fruits and related application have not been reported. SUMMARY

[0004] Based on the problems in the background art, the purpose of the present application is to provide a litchi endogenous polypeptide and application thereof in controlling plant diseases, in particular, application in controlling litchi Peronophythora disease or fruit diseases caused by Peronophythora litchii. The litchi endogenous polypeptide used to control plant diseases has the advantages of environmental friendliness, high safety, and the ability to stimulate plant systemic resistance, and is a green and sustainable control means.

[0005] In one aspect, the present application provides a litchi endogenous polypeptide P2, characterized in that the amino acid sequence of the litchi endogenous polypeptide P2 is shown in SEQ ID NO. 1.

[0006] The present application also provides a plant disease resistance inducer, characterized in that the plant disease resistance inducer comprises the aforementioned litchi endogenous polypeptide P2.

[0007] The main effective component of the plant disease resistance inducer comprises the litchi endogenous polypeptide P2. The plant disease resistance inducer can improve the ability of plants to resist diseases when applied to plants.

[0008] The application also provides a plant preservative characterized in that the plant preservative comprises the aforementioned litchi endogenous polypeptide P2.

[0009] In a preferred embodiment, the plant disease resistance inducer or the plant preservative further comprises a surfactant to enhance the adhesion of the plant disease resistance inducer or the plant preservative to the surface of the plant.

[0010] Further, the plant disease resistance inducer or the plant preservative of the application can further comprise at least one of a thickening agent, a stabilizer, a solubilizer, a humectant, and the like to optimize the physicochemical properties of the litchi endogenous polypeptide P2 solution and improve the efficiency of the litchi endogenous polypeptide P2.

[0011] In another aspect, the application provides the use of the aforementioned litchi endogenous polypeptide P2 or the aforementioned plant disease resistance inducer in the prevention and control of plant diseases.

[0012] In a preferred embodiment, the plant disease is litchi downy mildew.

[0013] Alternatively, the plant disease is a litchi disease caused by the pathogenic fungus Peronophythora litchii.

[0014] In a preferred embodiment, the concentration of the litchi endogenous polypeptide P2 in the plant disease resistance inducer is less than 20 μM, such as 1 μM, 5 μM, 10 μM, preferably 5-10 μM, or other concentrations.

[0015] In another aspect, the application provides the use of the aforementioned litchi endogenous polypeptide P2 or the aforementioned plant preservative in the preservation of plants.

[0016] In a preferred embodiment, the plant preservation is achieved by exogenous application of the litchi endogenous polypeptide P2 to improve the disease resistance of the plant.

[0017] Further, the exogenous application of the litchi endogenous polypeptide P2 improves the resistance of the plant to litchi downy mildew.

[0018] In a preferred embodiment, the plant preservation is the preservation of plants in the genus Litchi.

[0019] Further, the plant preservation is the preservation of litchi.

[0020] In a preferred embodiment, the concentration of the litchi endogenous polypeptide P2 in the plant preservative is less than 20 μM, such as 1 μM, 5 μM, 10 μM, preferably 5-10 μM, or other concentrations.

[0021] In the foregoing scheme, the litchi endogenous polypeptide P2 or the plant preservative or the plant disease resistance inducer can be applied to the plant by soaking, spraying, smearing or injection.

[0022] In the foregoing scheme, the plant can refer to a growing plant, or can refer to an in vitro organ of the plant.

[0023] The litchi endogenous polypeptide P2 or the plant preservative or the plant disease resistance inducer is used in a growing plant or an in vitro organ of the plant, which can inhibit the growth of Peronophythora litchii by improving the disease resistance of the plant.

[0024] Compared with the prior art, the present application has the following advantages: (1) The present application uses a biological method to obtain a litchi endogenous polypeptide P2, which is environmentally friendly, harmless to the human body, has high safety, and can stimulate plant systemic resistance, thereby improving the ability of the plant to resist diseases.

[0025] (2) The present application provides a new use of the litchi endogenous polypeptide P2, i.e. for preparing a plant disease resistance inducer or a plant preservative which is harmless to the human body, effective and safe.

[0026] (3) The present application first provides the application of the litchi endogenous polypeptide P2 in controlling fruit diseases, and by applying the litchi endogenous polypeptide P2, the plant diseases caused by Peronophythora litchii can be effectively controlled; the fruit quality is maintained, the shelf life is prolonged, and by applying in the forest, the plant diseases can be effectively controlled and the crop yield can be improved, which is a green and sustainable plant disease control method. BRIEF DESCRIPTION OF DRAWINGS

[0027] The method of the present application and its beneficial effects will be described in detail below in combination with the drawings and specific embodiments.

[0028] Figure 1 . Effect of litchi endogenous polypeptide P2 treatment on the growth of Peronophythora litchii on PDA plates. (A) Phenotype of Peronophythora litchii treated with different concentrations of P2; (B) Diameter of Peronophythora litchii lesion treated with different concentrations of P2, p<0.05.

[0029] Figure 2 . Effect of litchi endogenous polypeptide P3 treatment on the growth of Peronophythora litchii on PDA plates. (A) Phenotype of Peronophythora litchii treated with different concentrations of P3; (B) Diameter of Peronophythora litchii lesion treated with different concentrations of P3, p<0.05.

[0030] Figure 3Effects of litchi endogenous peptide P2 treatment (5 μM) on litchi fruit infected with Phytophthora downycium. (A) Phenotype of infected litchi; (B) Histogram of plaque diameter, where different letters on the bars represent significant differences (p < 0.05). Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0033] The following examples involve two polypeptides, both endogenous polypeptides of litchi. These polypeptides were obtained through bioinformatics analysis of the litchi genome, predicting potential functional sequences, and were synthesized artificially (Shanghai Xinhao Biotechnology Co., Ltd.). One of them is the litchi endogenous polypeptide P2, which is claimed in this invention and is abbreviated as P2. The amino acid sequence of the P2 peptide is SEQ ID NO.1: LASGPSPKGPGT. The other litchi endogenous polypeptide is P3, abbreviated as P3. The amino acid sequence of the P3 peptide is SEQ ID NO.2: LGGIKESGPSPRGEGH.

[0034] Example 1: Antibacterial effect of litchi endogenous peptides on culture medium Effects of litchi endogenous peptide (P2 and P3) treatment on the growth of *Phytophthora infestans* on litchi Phytophthora lichee was cultured on PDA plates at 28°C for 7 days. The spores were washed with sterile water and filtered through gauze. The filtrate was collected, and the spore concentration was adjusted to 1×10⁻⁶ using a spore counter. 6 10 μl of the above spore solution was dropped into the middle of PDA medium containing 0 μM P2 (CK) and PDA medium containing 5 μM, 10 μM, and 20 μM P2, respectively. Simultaneously, 10 μl of the above spore solution was dropped into the middle of PDA medium containing 0 μM P3 (CK) and PDA medium containing 5 μM, 10 μM, and 20 μM P3, respectively. After 11 days of incubation, the effects of P2 and P3 on the growth of *Phytophthora lichei* were compared. Figure 1 As shown in Figure A, treatment with endogenous polypeptides (P2) in litchi had no significant effect on the growth of *Phytophthora indicum*; except for a slight increase in colony diameter at 20 μM treatment, there were no significant differences among the other groups. Figure 1 B).

[0035] Similarly, the treatment of litchi endogenous polypeptide (P3) also had no significant effect on the growth of Peronophythora litchii Figure 2 A); the colony diameter of the 20 μM treatment group was slightly higher than that of the other groups, and there was no significant difference between the other groups Figure 2 B).

[0036] Example 2: Control of natural disease occurrence of litchi fruit by litchi endogenous polypeptides (P2 and P3) Litchi fruits harvested on sunny days, 80% mature, no mechanical damage and no disease and insect pests were selected, and the litchi fruits were randomly divided into three groups, 100 fruits in each group, and three replicates were set for each treatment group. The control group and the experimental group were placed in water, 5 μM P2 and 5 μM P3 solution respectively for 10 min, and the litchi fruits treated by soaking were dried. All litchi fruits were stored in a incubator at 25°C and a relative humidity of 85%, and the occurrence of disease was observed. After 3 days of storage, as shown in Table 1, it was found that the incidence of Peronophythora litchii disease in the CK group was 95%, the incidence of P2 group was 43%, and the incidence of P3 group was 85%. It is shown that the treatment of litchi endogenous polypeptide P2 can significantly control the occurrence of Peronophythora litchii disease. Therefore, litchi endogenous polypeptide P2 can be used as an effective component of preservative for litchi preservation.

[0037] Table 1. Effect of litchi endogenous polypeptide treatment on the natural incidence of Peronophythora litchii disease Treatment CK P2 P3 Average natural incidence 95% （a） 43% （b） 85% （a） Note: Different letters indicate significant difference (p<0.05), and the same letter indicates no significant difference.

[0038] The inventors found through in-depth research that although P2 and P3 had no effect on the growth of Peronophythora litchii, P2 treatment could significantly control the occurrence of Peronophythora litchii disease, while other litchi endogenous polypeptides (P3) had no significant effect on the control of litchi disease occurrence. It is shown that litchi endogenous polypeptide P2 can improve fruit resistance, and different endogenous polypeptides have certain differences in the effect on fruit resistance.

[0039] Example 3: Control of litchi fruit inoculation disease by litchi endogenous polypeptide (P2) Further, litchi endogenous polypeptide (P2) was used to treat litchi, and litchi fruits harvested on sunny days, 80% mature, no mechanical damage and no disease and insect pests were selected, and the litchi fruits were randomly divided into two groups, 30 fruits in each group, and three replicates were set for each group, 10 fruits in each replicate. The control group and the experimental group were placed in water and 5 μM P2 solution respectively for 5 min, and the litchi fruits treated by soaking were dried. Peronophythora litchii was inoculated by needle puncture method Peronophythora litchii ): 10 μl of Peronophythora litchii spore solution (1×10 6The spores (108 spores / ml) were dropped on the pricked parts of the litchi fruits. All the litchi fruits were stored in an incubator at 25°C and 85% relative humidity, and the disease occurrence was observed. After 3 days of inoculation, it was observed that the litchi fruit skin treated by P2 had lighter disease (A), and the diameter of the bacterial spot on the litchi fruit skin treated by P2 was significantly smaller than that of the control group CK (p<0.05, B). It was indicated that the treatment of P2 could effectively control the growth of the litchi Peronophythora litchii on the litchi fruits, and delay the occurrence of the disease caused by the litchi Peronophythora litchii. Figure 3 A), and the diameter of the bacterial spot on the litchi fruit skin treated by P2 was significantly smaller than that of the control group CK (p<0.05, Figure 3 B). It was indicated that the treatment of P2 could effectively control the growth of the litchi Peronophythora litchii on the litchi fruits, and delay the occurrence of the disease caused by the litchi Peronophythora litchii.

[0040] Based on the research results of the inventors, it was indicated that the litchi endogenous polypeptide P2 had no effect on the growth of the litchi Peronophythora litchii, but could specifically enhance the resistance of the plant host, realize the effective control of the disease, and effectively prevent the occurrence of the drug resistance of the pathogenic bacteria.

[0041] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the above-described embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A Litchi endogenous polypeptide P2, characterized in that: The amino acid sequence of the litchi endogenous polypeptide P2 is shown as SEQ ID NO.

1.

2. A plant disease resistance inducer, characterized by: The plant disease resistance inducer comprises the litchi endogenous polypeptide P2.

3. A plant preservative, characterized by: The plant fresh-keeping agent comprises the litchi endogenous polypeptide P2.

4. The plant disease inducing agent according to claim 2 or the plant preservative according to claim 3, wherein The plant disease resistance inducer or the plant fresh-keeping agent further comprises at least one of a surfactant, a thickening agent, a cosolvent, a humectant, and a stabilizer.

5. The litchi endogenous polypeptide P2 of claim 1 or the plant disease resistance inducer of claim 2 is applied in the prevention and control of plant diseases.

6. Use according to claim 5, wherein The plant disease is litchi downy mildew.

7. The litchi endogenous polypeptide P2 of claim 1 or the plant fresh-keeping agent of claim 3 is applied in the fresh-keeping of plants.

8. Use according to claim 7, wherein the compound is ###0002### The plant fresh-keeping is to improve the disease resistance of plants by exogenous application of the litchi endogenous polypeptide P2.

9. Use according to any one of claims 7-8, wherein the compound is ###00002### 8 The plant fresh-keeping is the fresh-keeping of plants in the genus Litchi.

10. Use according to any one of claims 7 to 8, wherein The concentration of the litchi endogenous polypeptide P2 in the plant fresh-keeping agent is less than 20 μM.

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