Preliminary Study On The Antifungal Mechanism Of Trans-Anethole Against Botryosphaeria And Preparation Of Its Water Emulsion

In this study,17 kinds of plant extracts were screened for their inhibitory activity in vitro using Botryosphaeria as the test bacteria,and a preliminary study on the mechanism of action of trans-Anethole,the main bacteriostatic component of Illicium verum extract with the best inhibitory effect.At the same time,a pesticide water emulsion made with trans-Anethole as the original drug was studied,and the inhibitory activity of the water emulsion on the test bacteria was measured.The main results are as follows:1.The in vitro inhibitory effect of 17 plant extracts on the test bacteria was screened by the mycelial growth rate method.The results showed that:When the test concentration was 2mg·m L^-1,the Illicium verum and Macleaya cordata extract had the strongest in vitro inhibitory effect on Botryosphaeria,and the inhibition rate reached 100% at 96 h after treatment.The virulence test of Illicium verum and Macleaya cordata extracts was performed.The EC₅₀ of Illicium verum extract was 0.2650mg·m L^-1,which was less than the EC₅₀ value of Macleaya cordata extract.2.The test concentration of trans-Anethole was 1mg·m L^-1.And the in vitro inhibition rate was 100% at96 h after treatment,and the EC₅₀ was 0.1600mg·m L^-1.Observed under a microscope,the mycelium treated with trans-Anethole(1mg·m L^-1)appeared deformed,and the surface of the fungus was uneven and had holes.At the same time,the contents of soluble protein,pyruvate and reducing sugar in the mycelium continued to decrease with the increase of the concentration of trans-Anethole at different concentrations.3.Using direct emulsification method,single factor method and multi-factor orthogonal method,through screening of different solvents and surfactants,the final formula of three 30% trans-Anethole water emulsions was determined to be trans-Anethole mass fraction of 30%;Solvent cyclohexanone mass fraction is 8%;Emulsifier（123K:1601=6:4,EL-40:123K =9:1,EL-40:1601=9:1）mass fraction is10%,5%,15%;The mass fraction of xanthan gum is 0.02%,0.01%,0.03%;The mass fraction of methanol is2%,1%,3%,and the rest is supplemented with water.All the indicators of the 30% trans-Anethole water emulsion prepared by the formula met the standards,and no oil separation and delamination occurred.4.Toxicity of three 30% trans-Anethole emulsions（123K:1601=6:4,EL-40:123K=9:1,EL-40:1601=9:1）to isolated test bacteria Force action,EC₅₀ are 0.0388mg·m L^-1,0.0375mg·m L^-1,0.0961mg·m L^-1.At the same time,30 kinds of 30% trans fennel water emulsion（123K:1601=6:4,EL-40:123K=9:1,EL-40:1601= 9:1）were tested at a concentration of 1mg.m-l.The indoor medicinal effect of the test bacteria,30%of trans-Anethole water emulsion（EL-40:1601=9:1）has the strongest inhibitory effect,and the inhibition rate is 100%.