Application of Vitex Essential Oil in Controlling Plant Diseases

Abstract

The invention belongs to the technical field of plant disease prevention and control, and specifically relates to a use of vitex essential oil in preventing and controlling plant diseases. The plant diseases prevented and controlled by vitex essential oil are root rot or anthracnose. Antibacterial tests have shown that vitex essential oil has a certain inhibitory effect on onion anthracnose pathogens, ash anthracnose pathogens, Fusarium solani, Fusarium oxysporum, and Fusarium odoriferum, among which the inhibitory effect on onion anthracnose pathogens is the most obvious.

Description

Technical Field

[0001] The invention belongs to the technical field of plant disease prevention and control, and particularly relates to use of vitex essential oil in preventing and controlling plant diseases. Background Art

[0002] Plant essential oils are natural antibacterial agents, known as golden liquids, and are mainly extracted from petals, buds, leaves, branches, resins and other plant structures of natural plants. Plant essential oils generally have an aroma and are often loved by many people for their unique taste. In addition to the aroma, essential oils also have many active functions, such as anti-oxidation, anti-aging, and anti-pathogenic microorganisms. These functions of essential oils have gradually brought them into the public eye, with more and more researchers and a wider range of applications.

[0003] Studies have shown that plant essential oils can affect the cell membrane and cell wall of fungi, increasing the permeability of fungal cell membranes, leading to loss of cell integrity and death of fungal cells. Plant essential oils can also affect the synthesis of fungal nucleic acids and proteins, and inactivate fungal cells by affecting the expression level of mycotoxin synthesis genes.

[0004] Root rot is named because the plant roots rot and cannot absorb water and inorganic salts from the soil normally, which makes the plant weaker and weaker and eventually dies. The main symptoms of root rot are yellowing and withering of the leaves of the whole plant until the roots rot. It is a plant disease caused by the combined action of many nematodes, fungi and bacteria, so its cause is complex and cannot be treated by simply inhibiting one pathogen.

[0005] The pathogens that cause root rot of Polygonatum sibiricum are mainly fungi such as Fusarium oxysporum and Fusarium solani. At present, in order to increase the yield of Polygonatum sibiricum, spraying chemical fungicides is the main measure to prevent and control root rot of Polygonatum sibiricum. However, chemical fungicides have problems such as toxicity and pesticide residues. This leads to chemical fungicide residues in Polygonatum sibiricum circulating on the market. Eating Polygonatum sibiricum roots with pesticide residues can easily affect human health, and chemical fungicides can also cause a certain degree of harm to the environment.

[0006] Based on the above reasons, the present invention intends to prevent and treat Polygonatum cyrtonema root rot by biological methods to reduce the impact of chemical fungicides on the environment. Plant essential oils are natural, green, pollution-free substances extracted from various plants with good antibacterial activity, which have significant effects on sterilization. In addition, essential oils also have the characteristics of biodegradability, easy volatility and low concentration residue, and are green and friendly to the ecological environment. Therefore, the present invention intends to seek a plant essential oil with better prevention and treatment effect on Polygonatum cyrtonema root rot. Summary of the invention

[0007] Based on the above technical objectives, the present invention provides a use of Vitex essential oil in preventing and treating plant diseases, the disease being root rot or anthracnose. Antibacterial tests have shown that Vitex essential oil has an inhibitory effect on onion anthracnose, ash anthracnose, Fusarium solani, Fusarium oxysporum and Fusarium odoriferum, which cause plant root rot.

[0008] The technical solution provided by the present invention is as follows:

[0009] In a first aspect, the present invention provides a use of vitex essential oil in preventing and controlling plant diseases, wherein the disease is root rot or anthracnose, and the vitex essential oil is extracted according to the following steps: taking vitex medicinal materials, extracting by steam distillation, and collecting the essential oil.

[0010] Preferably, the Vitex essential oil is used to inhibit onion anthracnose, ash anthracnose, Fusarium oxysporum, Fusarium solani or Fusarium odoriferum.

[0011] Preferably, the plant is Polygonatum sibiricum.

[0012] Preferably, the dosage ratio of Vitex truncatula to water is 1 g: 20-30 mL.

[0013] Preferably, the Vitex truncatum essential oil is prepared into a medicament.

[0014] Preferably, the agent further comprises an excipient that is acceptable in pesticides.

[0015] Preferably, the medicament is a 250-2000 times dilution of cinnamon essential oil.

[0016] Preferably, the medicament is a 250-1000-fold dilution of cinnamon essential oil.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] The invention provides a use of vitex essential oil in preventing and treating plant diseases. The plant diseases prevented and treated by vitex essential oil are root rot and anthracnose. Antibacterial tests show that when vitex essential oil is diluted 250 times, the antibacterial rate of onion anthracnose bacteria is the largest, which is 66.60%, and the antibacterial rate of Fusarium solani is the smallest, which is 27.56%. At 500 times, the antibacterial rate of Fusarium oxysporum is the largest, which is 62.23%, and the antibacterial rate of Fusarium solani is the smallest, which is 14.06%. At 1000 times, the antibacterial rate of onion anthracnose bacteria is the largest, which is 53.02%, and the antibacterial rate of Fusarium solani is the smallest, which is 13.44%. At 2000 times, the antibacterial rate of onion anthracnose bacteria is the largest, which is 53.70%, and the antibacterial rate of Fusarium oxysporum is the smallest, which is 8.05%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is the extracted Vitex essential oil;

[0020] Figure 2 This is the inhibitory effect of Vitex essential oil on onion anthracnose bacteria; Note: a to e in the figure are CK, diluted 250 times, 500 times, 1000 times, and 2000 times respectively;

[0021] Figure 3 This is the inhibitory effect of Vitex essential oil on Colletotrichum fraxinus; Note: a to e in the figure are CK, 250 times, 500 times, 1000 times, and 2000 times of dilution, respectively;

[0022] Figure 4 This is the inhibitory effect of Vitex essential oil on Fusarium solani; Note: a to e in the figure are CK, 250 times, 500 times, 1000 times, and 2000 times of dilution respectively;

[0023] Figure 5 This is a graph showing the inhibitory effect of Vitex essential oil on different pathogens. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific embodiments, and the embodiments of the present invention include but are not limited to the following embodiments.

[0025] 1. Materials

[0026] 1.1. Test plants and strains

[0027] Vitex truncatum was purchased from the Anguo Chinese medicinal materials market in Hebei Province.

[0028] Colletotrichum circinans, C. spaethianum, Fusarium oxysporum, F. solani, and F. redolens were all isolated from the diseased roots of Polygonatum cyrtonema and preserved in the Traditional Chinese Medicine Quality Inspection Laboratory of Taishan University.

[0029] 1.2 Experimental instruments and reagents

[0030] GI54T vertical automatic pressure steam sterilizer (Zhiwei Xiamen Instrument Co., Ltd.); VA214 electronic balance (Shanghai Jingtian Electronic Instrument Co., Ltd.); BHC-1300IIA2 clean bench (Altai Laboratory Equipment Beijing Co., Ltd.); water bath; electric heating jacket (Shanghai Shuli Instrument Co., Ltd.); essential oil extractor (Leigu Co., Ltd.).

[0031] Potato dextrose agar (PDA) and Tween-20 were both domestically produced and of analytical grade.

[0032] 2. Methods

[0033] 2.1. Extraction of Vitex truncatum essential oil

[0034] Weigh 100g of Vitex truncatum and extract essential oil in four times. Take 25g of the plant in a 1000mL round-bottom flask, add 500mL of distilled water at a ratio of 1:20, and stir with a glass rod to make the water submerge the material. Connect the rubber tube connected to the lower end of the condenser to the faucet, let the water fill the entire condenser, and the water flows out from the upper outlet of the condenser. Connect the condenser to the essential oil extractor and fix the essential oil extractor with an iron stand. Put the round-bottom flask in the electric heating mantle and heat it slowly, adjust the voltage to 220V, and when the essential oil starts to drip out, keep it slightly boiling for 2h, and stop heating until the amount of essential oil no longer increases. After the device cools down, open the piston at the lower end of the essential oil extractor, slowly release the essential oil, collect the essential oil in the extractor into a centrifuge tube, record the volume and name of the essential oil, and store it in a cool place. The remaining 75 g of Vitex truncatum was used to extract essential oil in the same manner, and the Vitex truncatum essential oils obtained by four extractions were combined and used as Vitex truncatum essential oil stock solution.

[0035] 2.2. Antibacterial experiment of plant essential oils on root rot pathogens

[0036] 2.2.1. Activation of fungi

[0037] Weigh 5.7744g of PDA culture medium into a conical flask, add 144mL of distilled water, seal the mouth, and place it in the sterilizer. Adjust the system and sterilize at 121°C for 20 minutes. In the clean bench, pour the PDA culture medium evenly into the culture dish near the sterile area of ​​the flame. Place the sterilized inoculation needle in the outer flame of the alcohol lamp and burn it repeatedly. After it cools down, use the inoculation needle to pick up a piece of the beaten bacteria sheet and place it in the center of the PDA culture medium. After sealing, place it in an incubator at 26°C for inverted culture for 7 days.

[0038] 2.2.2 Preparation of culture medium

[0039] PDA medium formula: Add 40.1 g of PDA medium powder to every 1000 mL of distilled water and sterilize in an autoclave at 121°C for 20 minutes.

[0040] 2.2.3 Antibacterial operation steps

[0041] Take the Vitex essential oil stock solution, add 0.5% Tween-20 by mass fraction for emulsification, and dilute it into four concentration gradients of 10 times, 20 times, 40 times, and 80 times.

[0042] 10-fold dilution process: Pipette 1.5 mL of Vitex essential oil stock solution into a 50 mL No. 1 centrifuge tube, add 1 mL of Tween-20, and then add 12.5 mL of double distilled water to prepare 15 mL of mother solution 1.

[0043] 20-fold dilution process: Take 7 mL of mother solution 1 and add it to 50 mL centrifuge tube No. 2, then add 7 mL of double distilled water to make 14 mL of mother solution 2.

[0044] 40-fold dilution process: Take 7 mL of mother solution 2 and add it to 50 mL centrifuge tube No. 3, add 7 mL of double distilled water to make 14 mL of mother solution 3.

[0045] 80-fold dilution process: Take 7 mL of mother solution 3 and add it to 50 mL No. 4 centrifuge tube, add 7 mL of double distilled water to make 14 mL of mother solution 4.

[0046] The sterilized PDA medium was cooled to about 50°C, and the diluted essential oil mother solutions of each gradient were added thereto and mixed thoroughly to dilute the essential oil concentrations to 250 times, 500 times, 1000 times, and 2000 times.

[0047] 250-fold dilution process: Take 6 mL of mother solution 1 and add it to 144 mL of PDA medium to make 150 mL.

[0048] 500-fold dilution process: Take 6 mL of mother solution 2 and add it to 144 mL of PDA medium to make 150 mL.

[0049] 1000-fold dilution process: Take 6 mL of mother solution 3 and add it to 144 mL of PDA medium to make 150 mL.

[0050] 2000-fold dilution process: Take 6 mL of mother solution 4 and add it to 144 mL of PDA medium to make 150 mL.

[0051] Pour the prepared PDA medium containing essential oil into a 90mm culture dish. The height of the medium poured is about one-third of the height of the culture dish. Put the activated strain aside for later use.

[0052] 2.2.3 Antibacterial operation steps

[0053] Use a sterilized puncher to burn on an alcohol lamp for a while. When the temperature drops, punch a sufficient number of bacterial slices on the activated strain culture dish. Use an inoculation needle to pick up the bacterial slices and insert them into the center of the culture dish. Repeat each gradient three times. Seal the culture dish with the bacteria and place it in an incubator upside down for 5 to 7 days. When the colony in the culture dish grows to two-thirds of the culture dish, measure the diameter of the colony.

[0054] 3. Data processing

[0055] When the colony grows to two-thirds of the culture dish, the diameter is measured using the cross method, and the data is photographed and recorded. The average diameter of the colony at each concentration is calculated using Excel, and the inhibition rate is finally obtained.

[0056] Antibacterial rate (%) = [(average diameter of control colonies - 6 mm) - (average diameter of treated colonies - 6 mm)] / (average diameter of control colonies - 6 mm) × 100%

[0057] EC 50 : half inhibitory concentration, also known as half maximum effect concentration, EC 50 It is often used as an indicator of drug safety. It means the drug concentration that has a certain obvious effect on 50% of the tested bacteria. For this test, it refers to the essential oil concentration that causes 50% of the tested bacteria to be inhibited.

[0058] The measured colony diameters of each bacterial species at each concentration were recorded in a table, and the average colony diameters at different concentrations were calculated, and the inhibition rate was calculated using the values.

[0059] Then, according to the obtained antibacterial rate, find the corresponding probability value in the probability value conversion table. Finally, use the logarithm of the essential oil concentration LogC as the X-axis and the probability value at each concentration as the Y-axis. Select the numerical range corresponding to the X-axis and the Y-axis, and use Excel to insert a scatter plot so that the resulting chart shows the toxicity regression equation Y=aX+b formula, the straight line direction and R 2 Value. 2 The closer it is to 1, the stronger the correlation between the values. The anti-value of the X value obtained by substituting y=5.0 into the toxicity regression equation is the EC 50 Value. By EC 50 The value indicates the antibacterial ability of the essential oil.

[0060] 4. Results and Analysis

[0061] 4.1 Essential Oil Extraction

[0062] The extraction rate of Vitex essential oil extracted in this experiment is about 0.4%, and 10 mL of Vitex essential oil is extracted. The color of Vitex essential oil is yellow, and the essential oil has a strong plant smell.

[0063] 4.2. Inhibitory effect of Vitex truncatum essential oil on five kinds of bacteria

[0064] According to the data, the average diameters of the control groups of onion anthracnose, ash anthracnose, oxysporum, fusarium solani, and fragrant fusarium were 49.7mm, 79.3mm, 26.3mm, 60.3mm, and 19.3mm, respectively. When diluted 250 times, the inhibition rate of onion anthracnose was the highest, at 66.60%, while the inhibition rate of fusarium solani was the lowest, at 27.56%. At 500 times, the inhibition rate of oxysporum was the highest, at 62.23%, while the inhibition rate of fusarium solani was the lowest, at 14.06%. At 1000 times, the inhibition rate of onion anthracnose was the highest, at 53.02%, while the inhibition rate of fusarium solani was the lowest, at 13.44%. At 2000 times, the inhibition rate of onion anthracnose bacteria was the highest, at 53.70%, while the inhibition rate of Fusarium oxysporum was the lowest, at 8.05%. Overall, the inhibitory effect of Vitex essential oil on onion anthracnose bacteria was obvious, but the inhibitory effect on Fusarium solani was not obvious. Figures 2 to 5 .

[0065] According to the obtained EC 50 The inhibitory effects of Vitex essential oil on the five fungi were ranked from best to worst as follows: Colletotrichum cepacia > Fusarium odoratum > Fusarium oxysporum > Colletotrichum ashwood > Fusarium solani, and the corresponding EC 50 The values ​​are: 0.000425556mL / L (2350 times dilution), 0.0020219476mL / L (495 times dilution), 0.0022957256mL / L (436 times dilution), 0.0450061756mL / L (22 times dilution), 3.3568035516mL / L (0.3 times dilution). That is, the inhibitory effect on Fusarium solani is the worst, and the inhibitory effect on onion anthracnose is the best, Table 1.

[0066] Table 1 EC of each fungus under the influence of Vitex truncatum essential oil 50 value

[0067] Bacteria Virulence regression equation <![CDATA[R 2 ]]> <![CDATA[EC 50 (mL / L)]]> Corresponding multiples Onion Anthracnose y=0.3854x+6.2992 0.8341 0.000425556 2350 Colletotrichum ashii y=0.6097x+6.4308 0.7225 0.045006175 22 Fusarium oxysporum y=1.5829x+9.1774 0.6741 0.002295725 436 Fusarium solani y=0.27x+4.858 0.1965 3.356803551 0.3 Fusarium odoratum y=1.5044x+9.0532 0.8158 0.002021947 495

[0068] The above embodiment is only one of the preferred implementation modes of the present invention and should not be used to limit the protection scope of the present invention. Any changes or modifications that are made to the main design concept and spirit of the present invention and have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention.

Claims

1. A use of Vitex essential oil in inhibiting onion anthracnose bacteria, ash anthracnose bacteria, Fusarium oxysporum, Fusarium solani or Fusarium odoratum, characterized in that: The Vitex essential oil is extracted according to the following steps: taking Vitex medicinal materials, extracting by steam distillation, and collecting essential oil.

2. The use according to claim 1, characterized in that The dosage ratio of Vitex truncatum to water is 1 g: 20~30 mL.

3. The use according to claim 1, characterized in that The Vitex truncatum essential oil is prepared into a medicament.

4. The use according to claim 3, characterized in that The medicament also includes pesticide-acceptable adjuvants.

5. The use according to claim 3, characterized in that: The medicament is a 250-2000 times dilution of Vitex essential oil.

6. The use according to claim 5, characterized in that The medicament is a 250-1000 times dilution of Vitex essential oil.

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