Antifungal Activity Of Chrysanthemum Coronarium L Extract On Watermelon Fusarium Wilt And Its Active Components

Watermelon Fusarium Wilt is one of the most common diseases of cucurbits, it occurs that causes watermelon yields and lower quality, causing great economic losses, severely limiting high yield and quality of watermelon production and local development. Currently in control of the disease is through the method of chemical synthesis of pesticides, but it is easy to loss to the environment soil easily form a compacted, and likely to cause very serious harm to people, the environment and animals. Nowadays more and more scholars at home and abroad a lot of research plant source bactericide, botanical fungicides are secondary metabolites produced by plants themselves. It have a defense mechanisms against pathogens, produced in the process of a variety of antibacterial substances, as biocide provides more information and template synthesis, the most important, it harm to the environment, water, animal and human harmless or less. Therefore, the agents from plant extracts more environmental protection and safety. Previous studies found that Chrysanthemum coronarium L.extract containing inhibitory substances of Fusarium oxysporum. This experiment is through of the antifungal substances of the minimal inhibitory concentration and minimum inhibitory concentration, response surface method to optimize the extraction process, the investigation of the preliminary exploration on the action mechanism and antifungal spectrum of Chrysanthemum coronarium L. extract. The main conclusions are as follows:1. Using the growth rate method, the Chrysanthemum coronarium L.extract was diluted two times, in the PDA culture medium and its antibacterial activity was measured.The results showed that the crude extracts from garden chrysanthemum has certain inhibitory effect on watermelon fusarium wilt.Crude extract with n-butanol extraction effect is best, its bacteriostatic rate reached 97.5%. its minimum inhibition concentration?MIC? and minimum fugicide concentration?MFC? is respectively 125 mg/mLand 500mg/m L, through the determination of virulence equation, Through the determination of virulence equation, its half bacteriostatic concentration of 206 mg/mL.To study and to four concentrations of crude extracts of 0, MIC, EC₅₀ and MFC on spore germination of Fusarium oxysporum, the lowest germination rate in MFC concentration.2. Using ultrasonic to extract the active substances of Chrysanthemum coronarium L.,through the single factor experiment and response surface optimization analysis method was used to study the ethanol concentration, extraction temperature, solid to liquid ratio and extraction time on the extraction of chrysanthemum antibacterial substances and optimized the extraction process parameters. The results revealed that the best extraction conditions were as follows: in the ethanol concentration of 95%, relation of primary and secondary of each variable on extraction yield of antifungal ingredient of X₃?temperature?> X₂?solid-liquid ratio? >X1?extraction time?, maximum extraction yield was achieved when the process was carried out with solid-liquid ratio of 26 mL·g^-1for 103 min at 35 °C.Under the optimum extraction conditions, model predictive value of 46.28% and the actual average of 45.56%, percent of contact area of the actual value and the predicted reached98.44%.3. To 0, MIC, EC₅₀ and MFC for concentration, through determination of the content of total sugar in the medium conductivity, mycelium, protein content and nucleic acid leakage and total DNA extraction is validated and the mycelial dry weight changes, a preliminary analysis of the mechanism of antimicrobial activity. The results show that adding Chrysanthemum coronarium L.extract into bacterial suspension, significantlyincreases the conductivity, the concentration EC₅₀ of liquid culture medium relative conductivity is the largest, reaching 0.27 ms/cm; culture time of mycelium of total sugar and soluble protein content decreased. In addition, mycelial biomass also decreased significantly, wet weight than the control reduce 64.34%, dry weight compared with CK decreased 78.63%; will mycelium of total DNA extraction and by agarose gel electrophoresis separation. The results showed that after Chrysanthemum coronarium L.extract liquid hypha DNA electrophoresis strip belt and the control group did not differ,might therefore mycelium DNA without leakage or degradation phenomenon.4. The 0.5g/mL Chrysanthemum coronarium L. extract liquid using double dilution method is formulated as a concentration gradient, on the determination of the antibacterial activity of 9 kinds of common plant pathogenic fungi, pathogen virulence equation, EC₅₀ correlation coefficients and confidence intervals are obtained. The results showed that the inhibitory effects of chrysanthemum extract of nine species of plant pathogenic bacteria from big to small order as follows: Pepper Phytophthora, lettuce Sclerotinia sclerotium,rice sheath blight fungus, jujube intends to Phoma, grape seat cavity bacteria, Botrytis cinerea in kiwifruit, hairy, kiwi intends to Phoma and citrus Penicillium. The strongest activity against Phytophthora capsici, lettuce Sclerotinia sclerotium two fungi. Their EC₅₀ were 76.87 mg / ml and 91.770 mg / ml that chrysanthemum extract is more sensitive of the two fungi, the strongest antibacterial activity. By gas phase chromatography mass spectrometry combined with detector of compounds of main components in chrysanthemum, 49 compounds were identified, including lactones and ketones respectively containing 15 and 9, relative content reached 3.3% and 3.92%, alcohol accounted for 7, relative content of 1.91%; acid accounted for three, relative content of0.09%; alkenes, aldehydes and phenols each accounted for 1, relative content respectively0.8%, 0.03%, 0.01%, indicating that chrysanthemum lactone and ketones is likely to have antibacterial activity of effective components of Watermelon Fusarium wilt.