Plant immune resistance inducer and application thereof in prevention and treatment of grape anthracnose

Abstract

The invention discloses a plant immune resistance inducer and application thereof in prevention and treatment of grape anthracnose, the plant immune resistance inducer comprises effective active ingredients of a flavonoid compound, and the flavonoid compound is quercetin. According to the application of the plant immune resistance inducer to prevention and treatment of grape anthracnose, the dosage is 50-200 micrograms per milliliter, and the application method is that the plant immune resistance inducer is sprayed to the surfaces of grape fruits before and / or after picking of the grape fruits. The plant immune resistance inducer can reduce the cell membrane permeability and MDA content, and reduce the damage of anthracnose; the content of flavonoids and total phenols, the activity of antioxidant enzymes and the activity of defensive enzymes are improved, and grape fruits are helped to defend anthracnose; the expression quantity of disease-resistant genes can be increased, related pathways of salicylic acid and lignin are activated, and the disease resistance of grape fruits is improved. Application and development of quercetin in immune resistance inducers are promoted, and the problems that chemical agents on the market at present pollute the environment, cause drug resistance of pathogenic bacteria and harm human health when used for preventing and treating grape diseases are solved.

Description

Technical Field

[0001] The invention relates to the technical field of biological agriculture, and in particular to a plant immune inducer and application thereof in preventing and controlling grape anthracnose. Background Art

[0002] Plant immune inducers refer to drugs or their metabolites that do not have direct bactericidal activity but can induce the plant immune system to enable plants to acquire or improve resistance to pathogens. Plant immune inducers are generally divided into two categories: plant immune inducers and plant immune inducer bacteria; plant immune inducers include proteins, oligosaccharides, biological metabolites or organic active small molecules, and plant immune inducer bacteria include Trichoderma and Bacillus. Plant immune inducers refer to a class of active molecules that can induce host plants to produce immune resistance responses. This immune resistance response involves aspects such as plant physiology and biochemistry, morphological reactions, accumulation of phytoalexins, and expression of disease-resistant genes. Inducers can be divided into biogenic and non-biogenic active molecules based on their sources. Biogenic inducers refer to living microorganisms, animals, plants and their metabolites, or active small molecules produced by the interaction between host plants and pathogens. These inducers stimulate plant defense responses by binding to receptors on the surface of plant cells, causing plants to produce systemic resistance.

[0003] Flavonoids can promote plant growth and adaptability to the environment, can be used as antifeedants to reduce plant pests, can cause osteoporosis or even death in insects; they can be produced in large quantities when plants encounter adversities such as oxygen stress, drought stress, and salt stress to maintain normal growth of the plant body, and have the effect of generally improving the plant's ability to resist adversities; they can be used as immune inducers to protect plants from the effects of adversities such as toxic metals such as aluminum, ultraviolet rays (UV-B and UV-A), and protect plant tissue cells and organs; they can protect plants from invasion by pathogens and induce plant immune responses, thereby improving plant disease resistance.

[0004] Quercetin is a flavonoid compound synthesized by plants themselves. Its chemical name is 3,3',4',5,7-pentahydroxyflavone. It is widely found in the flowers, leaves and fruits of fruits, vegetables and Chinese herbal medicines. The molecular structure contains phenolic hydroxyl groups, which have strong antioxidant and antibacterial properties and can remove oxygen free radicals and reactive oxygen. As an antioxidant, quercetin can protect the body from oxidative damage by external toxic substances and improve the body's disease resistance. Sanzani et al. compared the effects of various phenolic substances on the accumulation of Penicillium expansum and patulin, indicating that quercetin treatment has the most significant effect. Further studies have found that quercetin treatment can induce the expression of apple pathogenesis-related protein genes to improve disease resistance, and reduce the accumulation of patulin by controlling the transcription level of key genes for patulin synthesis. Quercetin reduces the ROS level of Aspergillus flavus, activates the antioxidant system transcription factor Yap1, increases the activity of the antioxidant enzyme system, and significantly improves POD, CAT, and SOD, thereby inhibiting the production of aflatoxin, and its anti-toxic activity is higher than that of tea polyphenols at the same concentration. However, there are no reports on the prevention and treatment of grape diseases with quercetin.

[0005] In the prior art, the prevention and control of grape anthracnose requires the use of a variety of chemical fungicides for preservation treatment, which inhibit and kill pathogenic microorganisms lurking on the surface of the fruit. The use of chemical fungicides will produce residual and accumulation of toxic and harmful substances, affect human health, and easily cause drug resistance in pathogenic bacteria. As people pay more and more attention to food safety, the development of natural plant immune inducers to replace chemical synthetic fungicides for disease prevention and control has become one of the research focuses of plant disease experts and scholars at home and abroad.

[0006] Therefore, the present invention provides a plant immune inducer with quercetin as the main active ingredient, and explores its application on grape anthracnose. Summary of the invention

[0007] The present invention aims to solve the above problems. In a first aspect, a plant immune inducer is provided. The effective active ingredients of the plant immune inducer include flavonoid compounds.

[0008] More preferably, the flavonoid compound is quercetin.

[0009] In a second aspect, the present invention also provides use of the plant immunity inducer as described above in preventing and controlling grape anthracnose.

[0010] Furthermore, the dosage of the plant immunity inducer is 50-200 μg / ml.

[0011] Furthermore, the plant immunity inducer is used by spraying it on the surface of grape fruits before and / or after picking the grape fruits.

[0012] Further preferably, the optimal dosage of the plant immunity inducer is 100 μg / ml.

[0013] Furthermore, the grapes are 'Kyoho' and 'Sunshine Rose'.

[0014] The present invention has the following advantages / benefits: The present invention provides a plant immune inducer with quercetin as the main active ingredient. The present invention uses 'Kyoho' grapes as the research object, studies the effects of different dosages of quercetin on grape anthracnose, and obtains that the dosage of 100 μg / ml quercetin has the best effect; in addition, the present invention experiments prove that the treatment of quercetin can effectively reduce the cell membrane permeability and the content of MDA, and can reduce the damage caused by grape anthracnose; quercetin can also improve the disease resistance of grapes by increasing the content of flavonoids and total phenols; and quercetin can It can increase the activity of its own oxidase (SOD / CAT / POD), improve its defense against pathogens and reduce the damage caused by anthracnose; quercetin treatment can increase the activities of PAL, PPO and β-1,3-GA at different time points, thereby improving the defense of grape berries against anthracnose; quercetin treatment can promote the expression of disease-resistant genes to improve resistance; quercetin may increase the resistance of grapes to anthracnose by activating the salicylic acid pathway; quercetin can activate the lignin pathway and improve the resistance of grape berries to anthracnose.

[0015] Quercetin is a flavonoid compound synthesized by plants themselves. It is widely found in the flowers, leaves and fruits of fruits, vegetables and Chinese herbal medicines. It is highly effective, safe and pollution-free, and is a potential disease control agent. The present invention specifically designs a plant immune inducer for preventing and treating grape anthracnose and its application, which promotes the application and development of quercetin in immune inducers and solves the problem that chemical agents currently on the market for preventing and treating grape diseases pollute the environment, cause pathogens to develop drug resistance, and endanger human health. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0017] Figure 1 :Quercetin treatment reduces the lesion diameter of 'Kyoho' fruit. Phenotypic diagram (A) and lesion diameter statistics (B); Figure 2 : Quercetin treatment reduced the relative electrical conductivity (A) and MDA content (B) of grape berries; Figure 3: Quercetin treatment increased the flavonoid content (A) and total phenolic content (B) in grape fruit; Figure 4 : Quercetin treatment increases the antioxidant enzyme activities in grape fruit. CAT activity (A), POD activity (B) and SOD activity (C); Figure 5 :Quercetin treatment improves the activity of defense enzymes in grape fruit. PAL activity (A), PPO activity (B), β-1,3-glucanase activity (C); Figure 6 : Quercetin treatment increased the expression levels of disease resistance-related genes VvPR1 (A) and VvPR5 (B) in grape berries; Figure 7 :Effects of quercetin treatment on the expression of key genes VvNPR1 (A), VvNPR4 (B) and VvICS (C) in salicylic acid biosynthesis in anthracnose-infected grape berries; Figure 8 :Effects of quercetin treatment on the expression of key genes Vv4CL (A), VvPAL (B) and VvCAD (C) in the lignin pathway of anthracnose-infected grape berries; Fig. 9 :Quercetin treatment reduces the incidence of fruit in the field (A) and the incidence statistics (B); Fig.10 : Quercetin treatment reduces the lesion diameter of 'Sunshine Rose' fruit; phenotypic diagram (A) and lesion diameter statistics (B). DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following embodiments are only for illustrating the present invention, and are not intended to limit the scope of the present invention in any way. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention. The experimental methods used in the present invention are conventional methods unless otherwise specified. The materials, reagents, etc. used in the present invention, unless otherwise specified, can be obtained from commercial channels. In addition, other terms used in the present invention, unless otherwise specified, generally have the meanings commonly understood by those of ordinary skill in the art.

[0019] Example 1: Experimental Materials and Methods 1.1 Experimental Materials The test materials were 'Kyoho' grape fruits from Maogong Mountain, Chengyang District, Qingdao City, Shandong Province (36°28′N, 120°46′E).

[0020] Quercetin (RQ0718) was purchased from Shanghai Ruiyong Biotechnology Co., Ltd. (RYON, Shanghai).

[0021] 1.2 Experimental methods 1) Material cultivation: Grape berries of the same maturity and size were selected and placed in the laboratory for 24 hours after picking to remove field heat.

[0022] The fruits were picked from well-managed orchards in Maogong Mountain and transported back to the laboratory on the day of picking. Fruits with regular shapes, no pests or diseases, no mechanical damage, and similar sizes were selected and placed in the laboratory for 24 hours to remove field heat.

[0023] Pathogen: Anthrax pathogen was isolated and purified by the research group and stored in PDA medium at 4 °C. Before use, it was cultured and activated in fresh PDA medium at 25 °C for 5 days. When used, a 5 mm bacterial cake was removed with a 5 mm borer.

[0024] 2) Experimental treatment: Control group: Grape berries were sprayed with phosphate buffer (pH 7.4) (containing 10% NaOH) and 5 mm anthracnose pathogen cake.

[0025] Treatment groups: Grape berries were sprayed with 50, 100 and 200 μg / ml quercetin in phosphate buffer (containing 10% NaOH) at pH 7.4 and 5 mm anthracnose pathogen cake.

[0026] The quercetin solution was processed as follows: quercetin of corresponding concentration was completely dissolved in a phosphate buffer solution (containing 10% 1M NaOH) at pH 7.4.

[0027] Treatment method: Grape berries were soaked in 2% sodium hypochlorite solution for 2 min, rinsed with distilled water 3-5 times, and dried naturally. The control group was sprayed with phosphate buffer solution (containing 10% NaOH) at pH 7.4. The treatment group was set up with three concentration gradients, and quercetin was sprayed with phosphate buffer solution (containing 10% NaOH) at pH 7.4 at concentrations of 50, 100, and 200 μg / ml, respectively, until liquid remained and reached saturation, and then placed for 2 hours to dry naturally. After drying, a uniform wound (5 mm×5 mm) was formed at the equator of each grape fruit with a sterile stainless steel nail (Φ=5 mm). The 5 mm bacterial cake removed by the puncher was pasted to the wound formed, and stored in an incubator with a relative humidity of 90% and a temperature of 28°C. The peel tissue at the junction of the diseased and healthy was taken at 0, 1, 2, and 3 days after inoculation, mixed, and stored at -80 °C for various indexes. Each treatment had 3 replicates and each replicate had 3 fruits.

[0028] 3) Determination of fruit stress index and other related indexes Measurement indicators: lesion diameter, MDA content, cell membrane permeability, flavonoid and total phenol content, SOD activity, POD activity, CAT activity, PPO activity, PAL activity, β-1,3-glucanase activity, and expression levels of disease resistance genes, salicylic acid synthesis genes, and lignin synthesis genes.

[0029] The diameter of the lesions was calculated using the cross-intersection method and the average value was taken; a lesion diameter ≥ 0.5 mm was considered to be diseased.

[0030] The malondialdehyde (MDA) content was determined by the thiobarbituric acid (TBA) method (Gao, 2018).

[0031] Total phenols and flavonoids were determined using the 1% HCl-CH3OH extraction method (Duan, 2017).

[0032] The catalase (CAT) activity was determined by UV absorption method (Zhu, 2014).

[0033] Superoxide dismutase (SOD) was determined by NBT (nitroblue tetrazolium) photoreduction method (Kan, 2019). The peroxidase (POD) activity was determined by the guaiac method (Cao Jiankang, 2007).

[0034] Phenylalanine ammonia lyase (PAL) was determined by trans-cinnamic acid changes (Chen Yuhuan, 2016).

[0035] The activity of polyphenol oxidase (PPO) was determined by the changes in the product formed by its catalysis of catechol (Cao Jiankang, 2007). β-1,3-glucanase activity was measured using a spectrophotometric kit (ADS-F-TDX012-47), produced by Addison.

[0036] The RNA of the samples was extracted by the modified cetyltrimethylammonium bromide (CTAB) method (Li Xidong, 2011). The first strand of cDNA was synthesized by reverse transcription using the EasyScript One-Step gDNA Removal and cDNA Synthesis SuperMix reverse transcription kit of Beijing Quanshi Biotechnology Co., Ltd. according to the instructions. The quantitative primers were designed online based on the tomato gene sequence in the NCBI database and the Primer-BLAST tool, and the quantitative primers were synthesized by Beijing Qingke Biotechnology Co., Ltd. The real-time fluorescence quantitative PCR reagent was selected from ArtiCanATMSYBR qPCR Mix of Beijing Qingke Biotechnology Co., Ltd. The system was: 10 μL iQTMSYBR Green Supermix, 2 μL cDNA, 0.4 μL upstream and downstream primers (10 μml / L), 7.2 μL ddH2O, and the reaction program was: 95℃ pre-denaturation for 30 s; 95℃ denaturation for 30 s, 56℃ annealing for 30 s, 72℃ extension for 30 s, 45 cycles, and each sample was repeated 3 times. SlActin was used as the internal reference gene for standardization and calibration, and the data were analyzed using the 2-ΔΔCT method. The primers used are shown in Table 1

[0037] Example 2: Experimental data and analysis 2.1 Effect of quercetin treatment on the diameter of grape anthracnose lesions Grape variety 'Kyoho' was selected as the experimental material, and 50, 100 and 200 μg / ml quercetin was applied externally until water droplets flowed down. The anthracnose pathogen cake was prepared using a 5 mm hole puncher, and a 5 mm × 5 mm wound was cut on the grape fruit with a sterile toothpick. The cake was pasted on the wound and stored in an incubator at 28 ℃ and 90% humidity. The phenotype was observed on days 2 and 3, and the lesion diameter was measured to calculate the inhibition rate.

[0038] The results are as follows Figure 1 As shown, when the dosage of quercetin was 100 μg / ml, Figure 1 -A shows that the lesion diameter is the smallest on the 2nd and 3rd day, and the effect is the best; Figure 1 -B is the specific value of each concentration treatment, and the best effect is achieved at a concentration of 100 μg / ml. It can be seen that quercetin can effectively improve the resistance of grapevine to anthracnose. Samples were taken at 0 d, 1 d, 2 d and 3 d, and the relevant disease resistance indicators of the 100 μg / ml quercetin group were measured.

[0039] 2.2 Effects of quercetin treatment on fruit cell membrane permeability and MDA content MDA is an important product of membrane lipid peroxidation. When its content increases, it indicates that the cell membrane structure is damaged. Related studies have shown that the lower the MDA content, the stronger the disease resistance of the plant. Relative conductivity is an important indicator of the degree of oxidative damage to the cell membrane.

[0040] To verify whether quercetin improves grape anthracnose resistance by activating the immune system, we measured cell membrane permeability and MDA content after treatment with 100 μg / ml quercetin. Figure 2 It was shown that quercetin treatment could effectively reduce the relative conductivity ( Figure 2 -A) and MDA content ( Figure 2 -B), which proves that quercetin can reduce the damage caused by grape anthracnose.

[0041] 2.3 Effects of postharvest quercetin treatment on total phenolic and flavonoid contents in grape berries Flavonoids and phenolic substances can inhibit the activity of pathogens. Secondly, these active substances can combine with toxic substances produced by pathogens, reduce the infection of pathogens to fruits, and improve the disease resistance of fruits.

[0042] To this end, the flavonoid content and total phenolic content after quercetin treatment were determined, and the results were as follows Figure 3 As shown, compared with the control group, the contents of flavonoids and total phenols in the quercetin treatment increased significantly in some periods, there were significant differences in flavonoids at 1 and 2 days, and there were significant differences in total phenols at 1 and 3 days. This shows that quercetin can increase the content of flavonoids and total phenols to improve the disease resistance of grapes.

[0043] 2.4 Effects of postharvest quercetin treatment on antioxidant enzymes in grape berries In order to explore whether quercetin treatment can increase the activity of antioxidant enzymes to regulate redox balance, we measured the activities of antioxidant enzymes SOD, CAT and POD in grapes after quercetin treatment. Figure 4 As shown in the figure, after the application of quercetin, the CAT activity of the two groups showed an overall upward trend after infection with anthracnose, and decreased slightly on the third day, but on the 2nd and 3rd days, the CAT activity of the grape fruit treated with quercetin increased to a greater extent. POD activity increased in both the control group and the treatment group compared with 0 days on the 1st, 2nd and 3rd day of pathogen infection. On the 1st and 2nd day, under the quercetin treatment, POD activity was significantly higher than that of the control group. SOD activity gradually increased during the pathogen infection process, from which it can be seen that grape fruit will make a defensive response after being infected by pathogens. Under the quercetin treatment, SOD activity increased faster and was significantly higher than that of the control group on the 1st and 3rd day. It can be seen that grape fruit treated with quercetin can improve its own antioxidant enzyme activity, improve its defense ability against pathogens, and reduce anthracnose damage.

[0044] 2.5 Effects of postharvest quercetin treatment on the activities of defensive enzymes in grape berries To explore whether quercetin treatment can increase the activity of defense enzymes in diseased grapes to enhance grape anthracnose resistance, we measured the activities of defense enzymes PPO, PAL and β-1,3-glucanase in grapes after quercetin treatment.

[0045] The results are as follows Figure 5 Show, PPO ( Figure 5 -B) The activity did not change significantly during the pathogen infection process. After quercetin treatment, there was no significant difference between the 0, 1 and 2 days and the control group. Only on the third day did a significant difference appear, which increased the PPO activity.

[0046] PAL ( Figure 5 -A) It first increased after infection with anthrax. It decreased on the third day, but was still higher than when not infected with anthrax. After quercetin treatment, the increase was greater than that of the control group, with significant increases on days 1 and 2, but no significant difference on the third day.

[0047] β-1,3 glucanase ( Figure 5 -C) is mainly found in plants, catalyzing the hydrolysis of β-1,3-glucosidic bonds, thereby destroying fungal cell walls, especially in synergy with chitinase, which can significantly inhibit the growth of fungi. When plants are infected or in other adverse conditions, cells can be induced to synthesize a large amount of β-1,3-GA to enhance the resistance of plants to adverse external stimuli. Therefore, the activity determination of β-1,3-GA is widely used in plant pathology and stress physiology research. After infection with anthracnose, the control group of β-1,3-GA first decreased and then increased slightly, while after quercetin treatment, it increased on the second day, which was significantly higher than the control group. There was no difference on the second day, and it increased significantly again on the third day. In summary, quercetin treatment can increase the activity of PAL, PPO and β-1,3-GA at different time points, thereby improving the defense ability of grape fruit against anthracnose.

[0048] 2.6 Effects of quercetin treatment on proteases related to grape berry disease progression PR1 and PR5 are key genes related to plant disease resistance. VvPR1 and VvPR5 were quantitatively determined at different times, such as Figure 6 As shown, VvPR1 ( Figure 6 -A) were significantly upregulated on days 1, 2, and 3, with a significant upregulation on days 1 and 2. Figure 6 -B) Up-regulated on days 2 and 3. The experimental results showed that quercetin treatment can promote the expression of disease resistance genes to improve resistance.

[0049] 2.7 Effect of quercetin on the expression of key genes in the grape salicylic acid pathway The plant hormone salicylic acid plays a key role in plant disease resistance and systemic acquired resistance. The receptors of SA in Arabidopsis are the NPR family proteins NPR1 and NPR4. Among them, NPR1 acts as a transcription activator, and the binding of SA increases its transcriptional activation activity. In contrast, NPR4 is a transcription repressor, and the binding of SA inhibits its repressor activity. ICS plays a key role in the salicylic acid biosynthesis pathway. Relevant literature reports that pathogen infection leads to ICS expression and thus induces SA synthesis.

[0050] Therefore, the expression levels of VvNPR1, VvNPR4, and VvICS were measured after exogenous quercetin administration. Figure 7 As shown, VvNPR1 ( Figure 7 -A) The expression level increased significantly at 2 and 3 days, VvNPR4 ( Figure 7 -B) The expression level decreased on days 2 and 3, while VvICS ( Figure 7 These results preliminarily suggest that quercetin may improve grapevine resistance to anthracnose by activating the salicylic acid pathway.

[0051] 2.8 Effect of quercetin on the expression of key genes in the grape lignin pathway Lignin is one of the important products in the phenylpropanoid metabolic pathway of plants. It provides the necessary strength, hydrophobicity and resistance to the harsh external environment for the plant cell wall. Among them, cinnamyl alcohol dehydrogenase (CAD) is a key enzyme in the lignin synthesis pathway, participating in the synthesis of S-lignin, G-lignin and H-lignin. 4-Coumaryl-CoA ligase (4CL) is a regulatory enzyme that regulates the lignin biosynthesis pathway. Studies have found that regulating the content of this enzyme can effectively regulate the content of lignin. PAL can directly or indirectly control the synthesis of some substances containing phenylpropanoid skeletons, such as lignin. In addition, since PAL is closely related to the growth, development and stress resistance of woody plants, it can directly affect the resistance, adaptability, fruit quality and other characteristics of fruit trees.

[0052] Therefore, we determined the expression of Vv4CL in grape berries ( Figure 8 -A), VvCAD ( Figure 8 -C) and VvPAL ( Figure 8 -B) Gene expression, the results are as follows Figure 8 As shown, the three genes were significantly upregulated at different times after quercetin treatment, among which Vv4CL and VvPAL were significantly expressed at 1 and 3 days, while VvCAD was significantly expressed at 2 and 3 days.

[0053] Therefore, we inferred that quercetin can activate the lignin pathway and improve the resistance of grape berries to anthracnose.

[0054] 2.9 Field trial of quercetin improving disease resistance of grape berries The field experiment was conducted in the Kyoho vineyard area of ​​Maogong Mountain (36°28′N, 120°46′E), Chengyang District, Qingdao City, Shandong Province. Quercetin and pH 7.4 phosphate buffer (containing 10% NaOH) were sprayed on the treatment group and the control group 64 and 71 days after flowering, respectively. Five bunches of grapes were selected for each treatment. To reduce other interference, grapes with similar positions were selected. Each spraying was carried out until water droplets dripped down to reach saturation. The incidence rate was counted every 7 days.

[0055] The experimental results are as follows Fig. 9 As shown, at 71 days after flowering, all groups showed symptoms, but the incidence rate was significantly reduced by exogenous quercetin application. The difference was more significant at 78 and 85 days after flowering. At 85 days after flowering, the incidence rate was reduced by 23.19% and 36.78% under 50 μg / ml quercetin and 100 μg / ml quercetin, respectively. This shows that quercetin also has a good effect in the field and has high applicability.

[0056] 2.10 Quercetin improves the anthracnose resistance of 'Sunshine Rose' In addition, in order to verify whether quercetin has a good control effect on other varieties, we selected the common market variety 'Sunshine Rose' for the experiment. As in the above experiment, 50, 100, and 200 μg / ml quercetin solution was applied externally. The results are as follows Fig.10 The results showed that quercetin can also improve the anthracnose resistance of Yangmingshan Rose and reduce the diameter of anthracnose lesions, and the best effect was achieved at 100 μg / ml quercetin, which was consistent with the results of Kyoho. It can be seen that quercetin has a good preventive effect on anthracnose of multiple grape varieties.

[0057] In summary, the plant immune inducer provided by the present invention can reduce cell membrane permeability and MDA content, reduce the damage of anthracnose; increase the content of flavonoids and total phenols, increase the activity of antioxidant enzymes and defense enzymes, and help grape fruit defend against anthracnose; and can increase the expression of disease resistance genes PR1 and PR5, and improve the disease resistance of grape fruit to diseases; through quantitative verification, Vv4CL, VvPAL, VvCAD, VvNPR1 and VvICS were induced to be highly expressed, and the expression of VvNPR4 was reduced, thereby activating salicylic acid and lignin-related pathways to improve the disease resistance of grape fruit. Field experiments further prove that 100 μg / ml quercetin has a good disease resistance effect. The above experiments show that quercetin at a concentration of 100 μg / ml can improve the self-defense ability of grape fruit and improve resistance to anthracnose.

[0058] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. A plant immune inducer, characterized in that: The effective active ingredients of the plant immune inducer include flavonoid compounds.

2. A plant immunity inducer according to claim 1, characterized in that: The flavonoid compound is quercetin.

3. Use of the plant immunity inducer as claimed in claim 1 in preventing and controlling grape anthracnose.

4. The use according to claim 3, characterized in that: The dosage of the plant immunity inducer is 50-200 μg / ml.

5. The use according to claim 3, characterized in that: The plant immunity inducer is used by spraying it on the surface of grape fruits before and / or after picking the grape fruits.

6. The use according to claim 3, characterized in that: The optimal dosage of the plant immune inducer is 100 μg / ml.

7. The use according to claim 3, characterized in that: The grapes are 'Kyoho' and 'Sunshine Rose'.

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