Plant immune inducer containing cyclic diguanylate and application thereof

Abstract

This invention belongs to the field of biopesticide technology and discloses a plant immune inducer containing cyclic diguanylic acid (cDGA) and its application. The final concentration of cDGA in this plant immune inducer is 0.5~1 μmol / L. After spraying, it can rapidly activate multiple immune responses in plants, including reactive oxygen species (ROS) bursts, callose accumulation, and efficient expression of disease resistance genes and ROS scavenging-related genes. By activating the plant's own immune system, it enhances the plant's resistance to various pathogens, showing significant control effects against bacterial spot fungus of tomato, Phytophthora, and Actinidia kiwifruit canker. This cDGA plant immune inducer also has advantages such as being environmentally friendly, low in toxicity, residue-free, and unlikely to induce drug resistance in pathogens, thus having broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of biopesticide technology and relates to a plant immune inducer containing cyclic diguanosine monophosphate and its application. Background Technology

[0002] Plants are susceptible to infection and damage from pathogenic microorganisms, including bacteria, fungi, and viruses, during their growth. These biological stresses from pathogens interfere with normal physiological metabolism, damage plant structure, and consequently affect plant growth, development, yield, and quality. Through long-term evolution, plants have developed their own defense system, capable of responding to pathogen invasion by recognizing invasion signals, activating immune system pathways, and synthesizing and accumulating immune-related substances to reduce harm. However, the basic activity of the plant's immune system is relatively low, and the activation speed and intensity of its defense response are limited. When a large number of pathogens invade, plants struggle to quickly and efficiently activate their defense mechanisms, failing to form an effective resistance.

[0003] Traditional plant disease control methods still primarily rely on antimicrobial compounds (chemical pesticides). While these compounds can rapidly inhibit or kill pathogenic microorganisms in the short term, achieving a certain level of disease control, they have been widely used in agricultural production. However, long-term, large-scale use of antimicrobial compounds can lead to a series of problems, including environmental pollution, excessive pesticide residues in agricultural products, and a gradual decrease in crop sensitivity to antimicrobial compounds. Plant immune inducers, also known as plant vaccines, are biological pesticides that activate the plant's own immune system to achieve disease and pest resistance. They do not require direct killing of pathogens to achieve plant protection and have advantages such as being environmentally friendly, leaving no residues, and being less likely to induce resistance. They have become a research hotspot in green agricultural disease control.

[0004] Currently, developed plant immune inducers can be mainly divided into three types: bio-based, chemical-based, and natural product-based inducers. Bio-based inducers commonly include oligosaccharides, proteins, and microbial metabolites, while chemical-based inducers are typically represented by salicylic acid, methyl jasmonate, and their derivatives. These plant immune inducers have shown some application potential in the control of certain plant diseases. However, from the perspective of practical application effects, existing plant immune inducers still have many shortcomings: for example, their immune activation ability is limited, failing to quickly and efficiently activate the plant's defense system; their spectrum of action is narrow, with significant differences in control ability against different types and species of pathogenic microorganisms, resulting in poor versatility. Therefore, developing a plant immune inducer with significant immune activation effects, a broad spectrum of action, and good environmental compatibility has important theoretical significance and application prospects. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a plant immune inducer containing cyclic diguanylic acid (cDGA) and its applications. The final concentration of cDGA in this plant immune inducer is 0.5–1 μmol / L. After spraying, it rapidly activates multiple immune responses in plants, including reactive oxygen species (ROS) bursts, callose accumulation, and efficient expression of disease resistance genes and ROS scavenging-related genes. By activating the plant's own immune system, it enhances the plant's resistance to various pathogens, showing significant control effects against bacterial spot fungus of tomato, Phytophthora, and Actinidia kiwifruit canker. This cDGA plant immune inducer also possesses advantages such as being environmentally friendly, low in toxicity, residue-free, and unlikely to induce drug resistance in pathogens, thus having broad application prospects.

[0006] On the one hand, the present invention provides a plant immune inducer containing cyclic diguanosine monophosphate, wherein the active ingredient of the plant immune inducer comprises cyclic diguanosine monophosphate;

[0007] The final concentration of cyclic diguanosine monophosphate in the plant immune inducer is 0.1~1 μmol / L; preferably, the final concentration of cyclic diguanosine monophosphate in the plant immune inducer is 1 μmol / L.

[0008] Furthermore, the plant immune inducer contains agriculturally acceptable adjuvants, including at least one of surfactants, stabilizers, preservatives, and carriers.

[0009] On the other hand, the present invention seeks protection for the application of the above-mentioned plant immune inducers in the prevention and control of plant diseases.

[0010] Furthermore, the pathogens causing the plant diseases include Pseudomonas syringa e pv. tomato , ‌ Phytophthora nicotianae 、 Pseudomonas syringae pv. actinidiae At least one of them; The plant immune inducer enhances the plant's resistance to the aforementioned pathogens.

[0011] Furthermore, the plant immune inducer activates the plant's defense response; The defense response includes at least one of reactive oxygen species burst, callosity deposition, expression of disease-resistant genes, and expression of reactive oxygen species scavenging enzymes.

[0012] The disease-resistant genes include PR1 Gene, PR2 Gene, PR5 At least one of the genes; The reactive oxygen species scavenging enzyme includes POD enzyme.

[0013] Specifically, through experiments, this invention has found that spraying or penetrating c-di-GMP into Arabidopsis thaliana, tobacco, and kiwifruit can rapidly activate multiple immune responses in plants, including reactive oxygen species explosion, callose accumulation, and efficient expression of disease resistance genes and reactive oxygen species scavenging-related genes. By activating the plant's own immune system, it enhances the plant's resistance to various pathogens and has significant control effects against bacterial spot fungus of tomato, Phytophthora, and kiwifruit canker fungus.

[0014] Furthermore, the present invention claims protection for a method for improving plant disease resistance, which includes applying the aforementioned plant immune inducer.

[0015] Furthermore, the application is at least one of foliar spraying, injection, and vacuum penetration.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: (1) This invention has discovered and confirmed through experiments that cyclic diguanylic acid (c-di-GMP) can be used as a plant immune inducer, breaking through the traditional understanding that c-di-GMP is only used as a second messenger to regulate bacterial physiological processes, and expanding the application field of c-di-GMP. After spraying or penetrating c-di-GMP into the leaves of Arabidopsis thaliana, tobacco, and kiwifruit, it can rapidly activate a variety of immune responses in plants, including reactive oxygen species bursts, callose accumulation, and efficient expression of disease resistance genes and reactive oxygen species scavenging-related genes. By activating the plant's own immune system, it enhances the plant's resistance to a variety of pathogens, including significant control effects against bacterial spot of tomato, Phytophthora, and kiwifruit canker.

[0017] (2) The c-di-GMP of this invention, as a plant immune inducer, has advantages such as being environmentally friendly, low in toxicity, residue-free, and unlikely to induce drug resistance in pathogens. It avoids the harm to the environment and human health caused by traditional chemical pesticides, meets the development needs of green agriculture and ecological agriculture, and has broad application prospects. The preparation process of c-di-GMP is simple and can be achieved through chemical synthesis or biosynthesis, making it easy to scale up production. c-di-GMP also has the advantage of being easy to use. It can stimulate a variety of immune responses in plants by spraying, improving the control effect against pathogens. The spraying method is simple, requiring no complicated equipment, and is easy to promote and apply in the field. It can effectively reduce agricultural production costs and improve crop yield and quality. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 Figure showing the accumulation of reactive oxygen species in Arabidopsis leaves of different treatment groups. Figure 1 Figure A in the figure shows the results of DAB staining and NBT staining of Arabidopsis leaves from different treatment groups to detect reactive oxygen species. Figure 1 Figure B in the graph shows the quantitative analysis results of reactive oxygen species in Arabidopsis leaves from different treatment groups. ns indicates no statistically significant difference. P >0.05); , , and The values ​​of 0.05, 0.01, 0.001, and 0.0001 respectively indicate that the differences are statistically significant at the significance levels. P <0.05, P <0.01, P <0.001, P <0.0001).

[0020] Figure 2 Figure showing the callose accumulation in Arabidopsis leaves of different treatment groups.

[0021] Figure 3 Figure 1 shows the expression of disease resistance genes and the POD enzyme activity in Arabidopsis leaves of different treatment groups. Figure 3 In the figure, A represents the concentration of different treatment groups of Arabidopsis leaves. AtPR2, AtPR5 and AtSOD A diagram showing gene expression. Figure 3 Figure B in the figure shows the POD enzyme activity content in Arabidopsis thaliana leaves of different treatment groups.

[0022] Figure 4 Inoculate Arabidopsis thaliana leaves sprayed with c-di-GMP with tomato bacterial spot pathogen. Pto The disease incidence rate of DC3000 7 days later. Figure 4 In the figure, A represents the phenotypic pattern of disease incidence; Figure 4 B in the figure represents the percentage of diseased areas on Arabidopsis leaves; Figure 4 C in the figure represents the determination of pathogen colonization in Arabidopsis thaliana leaves.

[0023] Figure 5 This figure shows the accumulation of reactive oxygen species in tobacco leaves from different treatment groups. Figure 5 Figure A in the figure shows the results of DAB staining detection of reactive oxygen species in Arabidopsis leaves from different treatment groups; Figure 5 Figure B in the figure shows the quantitative analysis results of reactive oxygen species in Arabidopsis thaliana leaves from different treatment groups.

[0024] Figure 6 Figure showing the callose accumulation in tobacco leaves of different treatment groups.

[0025] Figure 7 Figure 1 shows the expression of disease resistance genes and the determination of POD enzyme activity in tobacco leaves of different treatment groups. Figure 7 In the figure, A represents the concentration of tobacco leaves in different treatment groups. NbPR2, NbPR5, NbPOD A diagram showing gene expression. Figure 7 Figure B in the figure shows the POD enzyme activity assay in tobacco leaves of different treatment groups.

[0026] Figure 8 A diagram showing the disease incidence of tobacco leaves injected with c-di-GMP after inoculation with Phytophthora.

[0027] Figure 9 Figure showing the accumulation of reactive oxygen species in the leaf discs of kiwifruit in different treatment groups. Figure 9 Figure A in the figure shows the results of DAB staining of kiwifruit leaf discs in different treatment groups to detect reactive oxygen species. Figure 9 Figure B in the figure shows the quantitative analysis results of reactive oxygen species in kiwifruit leaves from different treatment groups.

[0028] Figure 10 Figure showing the accumulation of callose in kiwifruit leaves of different treatment groups.

[0029] Figure 11 Figure 1 shows the expression of disease resistance genes and the determination of POD enzyme activity in kiwifruit leaves of different treatment groups. Figure 11 In the figure, A represents the concentration of kiwifruit leaves in different treatment groups. AcPR5, AcPOD A diagram showing gene expression. Figure 11 Figure B in the figure shows the POD enzyme activity determination in kiwifruit leaves of different treatment groups.

[0030] Figure 12 Injecting c-di-GMP and inoculating with kiwifruit ulcer pathogen. Psa M228 disease status in kiwifruit leaf discs 7 days later. Figure 12 In the figure, A represents the phenotypic pattern of disease incidence; Figure 12 B in the figure represents the percentage of diseased areas on the kiwifruit leaves; Figure 12 C in the figure represents the colonization of pathogens in kiwifruit leaves. Detailed Implementation

[0031] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods and detection methods described in each embodiment are conventional methods; unless otherwise specified, the reagents and materials can be purchased commercially. Unless otherwise specified, the percentages in the following embodiments refer to mass percentages.

[0032] c-di-GMP standard (purity ≥98%), purchased from Sigma.

[0033] Arabidopsis thaliana ( Arabidopsis thaliana Col-0; Benedictine tobacco ( Nicotiana benthamiana Kiwi seedlings (variety Hongyang) A. chinensis var. chinensis Hongyang originated from grafted potted seedlings grown in the greenhouse of Northwest A&F University.

[0034] Pseudomonas syringae, a pathogenic strain of tomato, DC3000 ( Pseudomonas syringa e pv. tomato ), Phytophthora indicum ( Phytophthora nicotianae All strains, including *Pseudomonas syringae*, are preserved in the laboratory for a long period of time; the pathogenic strain M228 of *Actinidia syringae* is derived from a wild-type strain isolated and preserved from diseased leaves of kiwifruit in Meixian County, Shaanxi Province in 2010.

[0035] Hydrogen peroxide (H2O2) test kit and peroxidase (POD) test kit were purchased from OKA; aniline blue was purchased from Aladdin; 3,3-diaminobenzidine (DAB) and nitrotetrazole blue chloride (NBT) were purchased from Sigma.

[0036] Example 1 This embodiment provides the application of cyclic diguanylic acid (c-di-GMP) in inducing an immune response in Arabidopsis thaliana and enhancing its ability to resist the pathogenic tomato strain DC3000 of Pseudomonas syringae.

[0037] 1. Test Methods Preparation of c-di-GMP solution: Dissolve c-di-GMP in sterile water and shake thoroughly to obtain the c-di-GMP inducer; the preparation process is carried out under sterile conditions to avoid contamination by other microorganisms that may affect the induction effect.

[0038] Experimental grouping: Arabidopsis thaliana (Col ecotype) cultured to the 4-6 leaf stage was divided into a control group (sterile H2O) and a treatment group (sprayed with c-di-GMP solution at concentrations of 0.1, 0.5 and 1 μmol / L, respectively). Each group had 3 replicates, with 10 Arabidopsis thaliana plants in each replicate.

[0039] Treatment method: Use a spraying method to evenly spray the corresponding solution onto both sides of Arabidopsis leaves until a thin water film forms on the leaf surface without dripping.

[0040] 2. Indicator Testing (1) Detection of reactive oxygen species (ROS) bursts: 12 h after spraying different concentrations of c-di-GMP, the accumulation of ROS in Arabidopsis leaves was detected by DAB and NBT staining methods, and the hydrogen peroxide content in Arabidopsis leaves was detected by a hydrogen peroxide detection kit. Figure 1 ).

[0041] Depend on Figure 1 It can be seen that, compared with the control group, different concentrations of c-di-GMP treatment significantly induced the accumulation of hydrogen peroxide in Arabidopsis leaves. Figure 1 Among them, the 1 μmol / L concentration treatment group had the highest relative hydrogen peroxide content, and the difference compared with the control group was statistically significant. P <0.0001).

[0042] (2) Detection of callose deposition: 12 h after spraying c-di-GMP, Arabidopsis leaves were taken and the callose deposition was observed under a fluorescence microscope using the aniline blue staining method. Figure 2 ).

[0043] Depend on Figure 2 It was found that callose accumulation was observed in the leaves of Arabidopsis thaliana in all c-di-GMP treatment groups. Moreover, the callose accumulation gradually increased with the increase of c-di-GMP concentration, indicating that c-di-GMP can promote callose deposition in Arabidopsis thaliana and enhance the leaf's defense capabilities.

[0044] (3) Detection of antioxidant activity and resistance gene expression: After spraying different concentrations of c-di-GMP for 12 h, total RNA was extracted from Arabidopsis leaves, reverse transcribed into cDNA, and resistance genes in Arabidopsis were detected by RT-qPCR. AtPR2 , AtPR5 and AtSOD The level of expression, in Actin As an internal reference gene, calculate the relative expression level of the target gene. Figure 3 (A in the text). Additionally, Arabidopsis leaves treated with c-di-GMP for 12 h were used to determine peroxidase (POD) activity. Figure 3 (B in the middle).

[0045] Depend on Figure 3 As shown in A, compared with the control group, the c-di-GMP treatment group of Arabidopsis leaves contained... AtPR2 , AtPR5 and AtSOD Gene expression levels were all upregulated, with the 1 μmol / L c-di-GMP treatment group showing the highest upregulation. AtSOD The relative increase in gene expression was most significant, approximately five times that of the control group. Figure 3 As shown in B, compared with the control group, the POD activity of each c-di-GMP treatment group was significantly increased. These results indicate that exogenous c-di-GMP treatment can induce the expression of Arabidopsis resistance genes and enhance antioxidant enzyme activity, thereby improving the plant's tolerance to biotic stress.

[0046] (5) Disease control effect: After spraying 1 μmol / L c-di-GMP solution for 24 h, DC3000 (concentration OD) was used to control the disease. 600 ≈0.08) was evenly sprayed onto both sides of Arabidopsis leaves until a thin film of water formed on the leaf surface without dripping. After inoculation, the leaves were cultured at 22℃ under 16 h light / 8 h dark conditions for 7 days. The incidence of disease on the Arabidopsis leaves was then recorded. The percentage of diseased areas on the leaves was counted, and the concentration of viable pathogens was measured. Figure 4 ).

[0047] Depend on Figure 4 It can be seen that the leaf lesion area in the control group of Arabidopsis thaliana was 24%, while the leaf lesion area in the group treated with 1 μmol / L c-di-GMP decreased to below 6.9%, and the bacterial content in the c-di-GMP treatment group was significantly lower than that in the control group. P <0.001).

[0048] Example 2 This embodiment provides the application of cyclic diguanosine monophosphate (c-di-GMP) in inducing tobacco immune responses and enhancing tobacco's ability to resist antifungal activity.

[0049] 1. Test Methods Experimental group: Tobacco plants cultivated to the 5-7 leaf stage ( N. benthamiana The study group was divided into a control group (sterile H2O) and a treatment group (injected with c-di-GMP solution at concentrations of 0.1, 0.5 and 1 μmol / L, respectively), with 3 replicates in each group and 5 tobacco plants in each replicate.

[0050] Treatment method: The tobacco leaves were injected from the reverse side using an injection method, with the corresponding concentration of c-di-GMP solution (prepared in the same way as in Example 1) until they were completely soaked.

[0051] 2. Indicator Testing (1) Detection of reactive oxygen species (ROS) bursts: After injection of different concentrations of c-di-GMP for 12 h, the accumulation of ROS in tobacco leaves was detected by DAB staining, and the ROS content in tobacco leaves was detected by a hydrogen peroxide detection kit. Figure 5 ).

[0052] Depend on Figure 5It was found that 12 h after injection of c-di-GMP, reactive oxygen species bursts were detected in tobacco leaves of both the 0.5 μmol / L and 1 μmol / L treatment groups, and the hydrogen peroxide content was significantly higher than that of the control group. P The value <0.0001 indicates that c-di-GMP can induce the production of reactive oxygen species in tobacco leaves.

[0053] (2) Detection of callosity deposition: 12 h after injection of different concentrations of c-di-GMP, the callosity deposition was observed under a fluorescence microscope using aniline blue staining. Figure 6 ).

[0054] Depend on Figure 6 It was found that no obvious callose accumulation was observed in the tobacco leaves of the control group, while a large number of blue fluorescent spots (callose deposition) appeared on the leaf surface of the treatment group, and the number of spots increased with the increase of c-di-GMP concentration, indicating that c-di-GMP can promote callose accumulation in tobacco and enhance the leaf's defense ability.

[0055] (3) Detection of disease resistance gene expression and antioxidant activity: After injection of different concentrations of c-di-GMP for 12 h, total RNA was extracted from tobacco leaves and reverse transcribed into cDNA. RT-qPCR was used to detect disease resistance genes. NbPR2 , NbPR5 and NbPOD The level of expression, in Actin As an internal reference gene, calculate the relative expression level of the target gene. Figure 7 A). Tobacco leaves injected with c-di-GMP for 12 h were also taken, and POD activity was measured (…). Figure 7 (B in the middle).

[0056] Depend on Figure 7 As shown in A, compared with the control group, the tobacco leaves of the 1 μmol / L c-di-GMP treatment group had significantly higher concentrations of gluten. NbPR2 , NbPR5 and NbPOD The relative expression levels of all genes were significantly upregulated. Figure 7 As shown in section B, compared with the control group, the POD activity of the 0.5 μmol / L and 1 μmol / L c-di-GMP treatment groups was significantly increased. These results indicate that c-di-GMP can activate the immune defense response in tobacco.

[0057] (5) Disease control effect: 24 h after injection of 1 μmol / L c-di-GMP, 0.5 cm diameter Phytophthora tobaccois mycelium cakes were inoculated onto pre-cut tobacco leaves. After inoculation, the leaves were cultured at 25℃ under high humidity conditions of 16 h light / 8 h dark for 3 days. The occurrence of diseases on the tobacco leaves was then counted. Figure 8 ).

[0058] Depend on Figure 8 It can be seen that the diameter of lesions on tobacco leaves in the control group was larger, while the diameter of lesions on leaves treated with 1 μmol / L c-di-GMP was significantly reduced. P <0.01).

[0059] Example 3 This embodiment provides the application of cyclic diguanosine monophosphate (c-di-GMP) in inducing immune responses in kiwifruit and enhancing its resistance to ulcer pathogens.

[0060] 1. Test Methods Experimental groups: Kiwi seedlings (variety Hongyang, A. chinensis var. chinensis Hongyang was divided into a control group (sterile H2O) and a treatment group (vacuum permeation of c-di-GMP solution with concentrations of 0.1, 0.5 and 1 μmol / L, respectively), with 3 replicates in each group and 15 kiwi leaf discs in each replicate.

[0061] Treatment method: The kiwifruit leaves were prepared into leaf discs with a diameter of 11 mm using a vacuum perforator. The leaf discs were then vacuum-impregnated with a c-di-GMP solution of the corresponding concentration until the underside of the leaves was more than 90% wetted.

[0062] 2. Indicator Testing (1) Detection of reactive oxygen species (ROS) burst: After vacuum permeation with c-di-GMP for 12 h, the accumulation of ROS in the kiwifruit leaf disc was detected by DAB staining, and the hydrogen peroxide content in the kiwifruit leaf disc was detected by a hydrogen peroxide detection kit. Figure 9 ).

[0063] Depend on Figure 9 It can be seen that after immersion in c-di-GMP, the hydrogen peroxide accumulation in the 0.5 and 1 μmol / L treatment groups of kiwifruit leaves was significantly higher than that in the control group. P <0.05、 P <0.001), indicating that c-di-GMP can induce reactive oxygen species bursts in kiwifruit.

[0064] (2) Detection of callosity deposition: After vacuum permeation with c-di-GMP for 12 h, the callosity deposition was observed under a fluorescence microscope using aniline blue staining. Figure 10 ).

[0065] Depend on Figure 10It was found that no obvious callose accumulation was observed in the leaf discs of the control group kiwifruit, while a large number of blue fluorescent spots (callose deposition) appeared in the leaf discs of the treatment group. The number of spots increased with the increase of c-di-GMP concentration, indicating that c-di-GMP can promote callose accumulation in kiwifruit and enhance the leaf's defense capabilities.

[0066] (3) Detection of disease resistance gene expression and antioxidant activity: After vacuum permeation with c-di-GMP for 12 h, total RNA was extracted from kiwifruit leaf discs and reverse transcribed into cDNA. RT-qPCR was used to detect disease resistance genes. AcPR5 and AcPOD The level of expression, in GAPDH As an internal reference gene, calculate the relative expression level of the target gene. Figure 11 (A) Separately, kiwifruit leaves injected with c-di-GMP for 12 h were used to determine POD activity ( ). Figure 11 (B in the middle).

[0067] Depend on Figure 11 As can be seen from A in the figure, the 1 μmol / L c-di-GMP treatment group AcPR5 and AcPOD The relative expression level of the gene was significantly higher than that of the control group, indicating that c-di-GMP can activate the expression of disease-resistant genes in kiwifruit and initiate an immune defense response. Figure 11 As shown in B, compared with the control group, the POD activity of the 1 μmol / L c-di-GMP treatment group was significantly increased. After vacuum infiltration of c-di-GMP, the plant defense mechanism was activated, and the tolerance to biological stress was significantly improved.

[0068] (5) Disease control effect: After vacuum permeating the kiwifruit leaf disc with 1 μmol / L c-di-GMP for 24 h, the inoculation concentration was 1×10⁻⁶ using the vacuum impregnation method. 4 kiwifruit ulcer pathogens (CFU / mL) Psa M228, after inoculation, leaves were laid face down on water agar plates and cultured at 16℃ in the dark for 7 days. The formation of lesions on the kiwifruit leaf discs was observed, and the average lesion area was calculated. Figure 12 ).

[0069] Depend on Figure 12 As shown in B, the lesion area of ​​the leaf discs in the control group was four times the average lesion area in the treatment group, and the pathogen content of the leaf discs in the control group was also significantly higher than that in the c-di-GMP treatment group. Figure 12 (C in the text). The above results indicate that c-di-GMP can effectively inhibit the growth of pathogens in the leaf disc of kiwifruit and enhance the immune response of kiwifruit leaves.

[0070] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope defined by the present invention.

Claims

1. A plant immune inducer containing cyclic diguanosine monophosphate, characterized in that, The active ingredient of the plant immune inducer includes cyclic diguanosine monophosphate; The final concentration of cyclic diguanosine monophosphate in the plant immune inducer is 0.1~1 μmol / L.

2. The plant immune inducer according to claim 1, characterized in that, The final concentration of cyclic diguanosine monophosphate in the plant immune inducer is 1 μmol / L.

3. The plant immune inducer according to claim 1, characterized in that, The plant immune inducer contains agriculturally acceptable adjuvants, which include at least one of surfactants, stabilizers, preservatives, and carriers.

4. The application of the plant immune inducer according to any one of claims 1 to 3 in the prevention and control of plant diseases.

5. The application according to claim 4, characterized in that, The pathogens causing the plant diseases include Pseudomonas syringa e pv. tomato , Phytophthora nicotianae 、 Pseudomonas syringae pv. actinidiae At least one of them; The plant immune inducer enhances the plant's resistance to the aforementioned pathogens.

6. The application according to claim 4, characterized in that, The plant immune inducer activates the plant's defense response; The defense response includes at least one of reactive oxygen species burst, callosity deposition, expression of disease-resistant genes, and expression of reactive oxygen species scavenging enzymes.

7. The application according to claim 6, characterized in that, The disease-resistant genes include PR1 Gene, PR2 Gene, PR5 At least one of the genes.

8. The application according to claim 6, characterized in that, The reactive oxygen species scavenging enzyme includes POD enzyme.

9. A method for improving plant disease resistance, characterized in that, This includes the application of the plant immune inducer as described in any one of claims 1 to 3.

10. The method for improving plant disease resistance according to claim 9, characterized in that, The application is at least one of foliar spraying, injection, and vacuum penetration.

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