Application of farnesol as an agricultural fungicide in plant bacterial diseases

Abstract

The invention discloses the application of farnesol as an agricultural fungicide in plant bacterial diseases, and belongs to the field of plant disease prevention and control. The invention discloses the application of farnesol as an agricultural fungicide in plant bacterial diseases, and has good inhibitory effects on rice bacterial leaf blight, rice bacterial leaf streak, citrus canker, cabbage black rot, tomato bacterial spot, kiwi canker, tobacco bacterial wilt, cucumber bacterial angular spot, potato bacterial wilt, soybean bacterial spot, tomato canker, etc. Farnesol is an extract of natural plants and is environmentally friendly. The invention provides a new use of farnesol, which can be used in the prevention and control of plant bacterial diseases in the agricultural field, and provides a new approach for the research and development and creation of new pesticides.

Description

Technical Field

[0001] The invention relates to the field of plant disease prevention and control, and in particular to the application of farnesol as an agricultural fungicide in plant bacterial diseases. Background Art

[0002] Plant diseases caused by plant bacterial infections are gradually getting worse, producing a variety of symptoms on various plant and fruit species, including leaf blight, leaf spot, bacterial wilt, canker, rot and deformity. It is estimated that more than 650 species of bacteria have been found in the world to cause bacterial plant diseases, which can spread rapidly in food crops (such as rice, corn, wheat and potatoes), cash crops (such as tobacco and soybeans), fruit crops (such as citrus, kiwi, mango, peach, apricot), vegetable crops (such as cucumber, tomato, pepper, onion), etc. This situation inevitably seriously affects the quality and yield of crops, thereby damaging global agricultural production.

[0003] Due to its advantages such as high efficiency and rapid effect, agricultural fungicides have become the most important means of preventing and controlling bacterial plant diseases. However, due to the frequent use of traditional fungicides and the single antibacterial mode of action, the problem of drug resistance in plant pathogens is becoming increasingly serious. According to literature reports, chlorothalonil, as the main agent for preventing and controlling rice bacterial leaf blight, has been monitored in the field for corresponding resistant strains, indicating that rice bacterial leaf blight fungi have developed resistance to chlorothalonil. In addition, traditional fungicides have other disadvantages, such as cross-resistance and environmental ecological safety issues. In summary, the drug resistance of plant pathogens has become a key scientific issue restricting the research and development of pesticides. There is an urgent need to develop antibacterial drugs with novel structures, unique mechanisms of action, high efficiency and low toxicity to replace traditional fungicides.

[0004] Biofilm, also known as biofilm, is not only the main place for bacterial growth and reproduction, but also an important barrier for bacteria to resist exogenous harmful substances. Therefore, biofilm is one of the important mechanisms for bacterial resistance and the main reason why many plant bacterial diseases are difficult to control. Bacteria produce biofilms during growth and reproduction. There are various major biomacromolecules such as proteins, polysaccharides, DNA, RNA, peptidoglycan, lipids and phospholipids in biofilms. In addition, the formation of biofilms is a dynamic process, including the initial adhesion of bacteria, biofilm development and mature diffusion. The strategy of targeting virulence factors such as biofilms can effectively avoid the problem of drug resistance caused by drug pressure. Therefore, inhibiting the formation of bacterial biofilms and thus inhibiting the infection process of bacteria to achieve disease resistance has become an important direction for the current development of new pesticides. Therefore, mining new targeted biofilm inhibitors from natural compounds is expected to accelerate the development of new pesticides. Summary of the invention

[0005] The purpose of the present invention is to provide the use of farnesol as an agricultural fungicide in plant bacterial diseases to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The invention provides application of farnesol as an agricultural fungicide in treating plant bacterial diseases.

[0008] Preferably, the structural formula of the farnesol is

[0009]

[0010] Preferably, the isomers of farnesol are trans-trans, trans-cis, cis-trans, and cis-cis.

[0011] Preferably, the plant bacterial diseases include diseases caused by the pathogenic bacteria of rice white leaf blight, Xanthomonas oryzae pv. oryzae, Xanthomonas campestris pv. rapeseed, Pseudomonas syringae tomato leaf spot pathotype, Pseudomonas syringae kiwifruit pathotype, Ralstonia solanacearum, Pseudomonas syringae cucumber angular spot pathotype, Pseudomonas solanacearum, Xanthomonas solanacearum soybean pathotype or Corynebacterium michiganensis tomato canker pathogen.

[0012] Preferably, the half inhibitory concentration (EC 50 ) is 23.8mg / L.

[0013] Preferably, the half inhibitory concentration (EC 50 ) is 8.25mg / L.

[0014] Preferably, the half inhibitory concentration (EC 50 ) is 10.9mg / L.

[0015] The present invention also provides a method for preventing and controlling agricultural diseases, which uses agricultural fungicides to spray crops for disease prevention and control. The diseases include rice white leaf blight, rice bacterial leaf streak, citrus canker, cabbage black rot, tomato bacterial spot, kiwi canker, tobacco bacterial wilt, cucumber bacterial angular spot, potato bacterial wilt, soybean bacterial spot or tomato canker.

[0016] The present invention discloses the following technical effects:

[0017] The present invention is the first to study farnesol as a fungicide to control plant bacteria. Compared with traditional fungicides, farnesol as a natural product has the advantages of being green, safe, and degradable by soil microorganisms. The present invention verifies the half inhibitory concentration (EC 50) of farnesol on rice bacterial blight by experiments. 50 ) was 23.8 mg / L, and the half inhibitory concentration (EC 50 ) is 8.25 mg / L, and the half inhibitory concentration (EC 50 ) is 10.9mg / L.

[0018] Biofilm, also known as biofilm, is not only the main place for bacterial growth and reproduction, but also an important barrier for bacteria to resist exogenous harmful substances. Therefore, biofilm is one of the important mechanisms for bacterial resistance and is also the main reason why many plant bacterial diseases are difficult to control. The present invention verifies that farnesol has an inhibitory effect on the biofilm of plant pathogenic bacteria, can effectively inhibit the formation of bacterial biofilm, thereby inhibiting the bacterial infection process and achieving disease resistance. The present invention provides a new use of farnesol, which can be used in the prevention and treatment of plant bacterial diseases in the agricultural field, and provides a new way for the research and development and creation of new pesticides. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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 will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 Crystal violet staining of farnesol-treated biofilms. DETAILED DESCRIPTION

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0023] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0024] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0025] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0026] Farnesol (95%) in the present invention was purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd., the rice bacterial leaf blight pathogen was provided by the research group of Professor Zhou Mingguo of Nanjing Agricultural University; the citrus canker pathogen was preserved by the research group of Professor Yang Song; and the rice bacterial stripe pathogen was provided by the research group of Professor Zou Lifang of Shanghai Jiaotong University.

[0027] Example 1 Testing the effective medium concentration EC of farnesol against plant pathogens using turbidity method 50

[0028] The test subjects were Xanthophyton oryzae (Xoo), Xanthophyton citri citri (Xac) and Xanthophyton streak (Xoc). Thiophanate-copper (20% wettable suspension) and chlorothalonil (90% original drug) were used as test controls, and DMSO dissolved in the culture medium was used as a blank control.

[0029] 1.1 Inoculate Xanthoceras oryzae, Xanthoceras citri citri and Xanthoceras oryzae into NB medium respectively, and culture them in a constant temperature shaker at 28°C and 180 rpm until the logarithmic growth phase.

[0030] 1.2 Use the two-fold dilution method to prepare NB liquid culture medium containing different concentrations of farnesol (100, 50, 25, 12.5, 6.25 μg / mL), respectively, with farnesol, thiophanate-methyl (20% wettable suspension) and chlorpyrifos (90% original drug), and take 5 mL of each into a test tube.

[0031] 1.3 Add 40 μL of NB liquid culture medium containing plant pathogenic bacteria to the test tubes containing different concentrations of drugs in step 1.2, respectively, and shake in a constant temperature shaker at 28°C and 180 rpm. The rice white leaf blight pathogen is cultured for 36 hours, the citrus canker pathogen is cultured for 48 hours, and the rice bacterial leaf streak disease is cultured for 36 hours.

[0032] 1.4 Measure the OD of each bacterial concentration on a spectrophotometer 595 The OD of the corresponding concentration of toxic sterile NB liquid culture medium was also measured. 595 value.

[0033] Corrected OD value = OD value of bacterial culture medium - OD value of sterile culture medium

[0034] Inhibition rate % = [(corrected control culture medium bacterial solution OD value - corrected toxic culture medium OD value) / corrected control culture medium bacterial solution OD value] × 100

[0035] The experimental results of some target compounds are shown in Table 1.

[0036] Table 1 EC values ​​of farnesol against plant pathogenic bacteria Xanthoceras oryzae, Xanthoceras citri citri and Xanthoceras oryzae 50 value

[0037]

[0038] EC 50 Median effective concentration (MEC) is an important indicator for evaluating the sensitivity of plant pathogens to compounds. It is also an important parameter for setting compound concentration when studying the mechanism of action of target compounds. In the concentration gradient experiment, the two-fold dilution method was used to set 5 appropriate concentrations. Finally, the inhibition rate of the agent on plant pathogens and the concentration of the agent were converted into logarithmic values. The toxicity curve was obtained through regression analysis using SPSS software, and the EC was calculated. 50 .

[0039] As can be seen from Table 1, farnesol exhibited excellent in vitro antibacterial activity against Xanthomonas oryzae. 50 =23.8mg / L, its in vitro antibacterial activity was significantly better than that of the commercial control drug chlorpyrifos (EC 50 =31.1 mg / L) and thiophanate-methyl (EC50>50 mg / L); farnesol showed excellent in vitro antibacterial activity against citrus canker bacteria, with an EC 50 =10.9mg / L, its in vitro antibacterial activity is significantly better than the commercial control drug chlorpyrifos (EC 50 >50mg / L) and thiophanate-methyl (EC 50>50mg / L); farnesol showed excellent in vitro antibacterial activity against rice bacterial leaf streak, and its EC 50 =8.25mg / L, its in vitro antibacterial activity is significantly better than the commercial control drug chlorpyrifos (EC 50 >50mg / L) and thiophanate-methyl (EC 50 >50mg / L).

[0040] Example 2

[0041] Biofilm, also known as biofilm, refers to the aggregates of bacteria and their secretions formed when they adhere to the surface of living or non-living objects. It plays a very important role in the drug resistance of plant pathogens. The crystal violet staining method is used to study biofilm formation.

[0042] Resuspend Xoo culture to OD 595 =0.6-0.8, dilute the resuspended Xoo bacterial solution with sterile NB medium to adjust the OD value to 0.2, add 150 μL of bacterial suspension to a sterile 96-well plate. Then add 1% DMSO or farnesol to the bacterial suspension to make the farnesol concentration in the bacterial suspension 0, 0.25×EC 50 , 0.5×EC 50 , 1×EC 50 , 2×EC 50 , 4×EC 50 , 8×EC 50 Each treatment was repeated 8 times and the culture medium was placed in an incubator at 28°C for 72 h.

[0043] After incubation, use a 200 μL pipette to gently remove the bacterial suspension, wash away excess suspended cells with sterile water, and then dry at room temperature for 4 hours. Add 200 μL of 0.1% crystal violet solution (w / v) to each well for staining for 15 minutes, remove the crystal violet solution, wash away excess crystal violet solution with sterile water, and then dry in a 60°C oven for 1 hour, then add 200 μL of 95% ethanol solution to completely dissolve the crystal violet, and finally measure the OD by an enzyme reader. 570 to determine the biofilm content.

[0044] like Figure 1 As shown, the CK in the control group was dark purple, and as the concentration of farnesol increased, the purple color in the treatment group became significantly lighter, which preliminarily indicated that farnesol had an inhibitory effect on Xoo biofilm.

[0045] Therefore, it can be seen that farnesol has a good inhibitory effect on pathogenic bacteria. Preliminary research shows that farnesol can potentially affect the biofilm formation of plant pathogenic bacteria. This natural product has extremely high research value in preventing and controlling plant bacterial diseases.

[0046] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. Application of farnesol as an agricultural fungicide in plant bacterial diseases, characterized in that: The plant bacterial diseases are diseases caused by Xanthoceras oryzae, Xanthoceras citri citri and / or Xanthoceras oryzae.

2. A method for preventing and controlling agricultural diseases, characterized in that: Using agricultural fungicides to spray crops for disease prevention and control, wherein the diseases are caused by Xanthomonas oryzae, Xanthomonas citri var. citrifolia and / or Xanthomonas oryzae; The agricultural fungicide is farnesol.

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