Preliminary Study On The Inhibitory Effect Of Chelerythrine On Phytophthora Capsici

Phytophthora capsici is a devastating pathogen that harms vegetable production in nature.It can harm a variety of vegetables and crops,and bring enormous pressure to vegetable growing.Thus it is urgent to develop new and safe biological control methods.Chelerythrine is extracted from the common plant chelerythrine,which belongs to the triphenylamine quaternary alkaloid in alkaloids.It has been studied in terms of inhibiting the plant diseases in agronomy,but it has not yet been applied to prevention and control of oomycete diseases.This paper took P.capsici as the research object,and conducted related research from the aspects of screening and identification,chelerythrine’s inhibitory effect on P.capsici in vitro.The main research results were as follows:(1)P.capsici,the pathogen in the fruits of field-affected peppers,was screened out;(2)In vitro inhibition of P.capsici,from the observation of the ultrastructure of P.capsici,determination of the colony growth rate and spore germination,cell membrane and cell wall permeability of P.capsici treated with chelerythrine,malondialdehyde content and the activities of antioxidant enzymes and respiratory metabolism-related enzymes,it was found that chelerythrine significantly shrinked the hyphae of P.capsici,and the colony growth of P.capsici.speed and spore germination rate were strongly inhibited.When the concentration of chelerythrine reached 10 μg/m L,the colony growth was completely inhibited,and the inhibition rate of zoospore germination of P.capsici reached 65.16% at 24 h and 73.72% at 48h;the inhibition rate of zoosporangium of P.capsici at 48 h was 91.38%.Compared with the results of control group,the UV absorbance value of P.capsici bacteria solution at 280 nm in each concentration treatment group increased significantly,and after culturing for 24 h,the malondialdehyde content of the 10 μg/m L chelerythrine treatment group was compared with the control group.group rose by 75.15%.Low concentrations of chelerythrine generally improved the antioxidant enzyme activity of P.capsici,while the results of high concentrations of chelerythrine were lower than that of low concentrations at the later stage.Chelerythrine could affect the glycolysis process and the tricarboxylic acid cycle process of P.capsici,so that the enzyme activities related to glycolysis were significantly reduced,and the enzyme activities related to the tricarboxylic acid cycle were increased.(3)In the pot experiment,P.capsici was artificially inoculated on pepper plants,and pesticides with chelerythrine as the main component were used to prevent and control pepper blight.2000 times of liquid significantly inhibited the occurrence and spread of pepper blight.The average height of plants in the treatment group was 14.500 cm,and the average height of plants in the natural growth group was 14.075 cm.The difference of plant heights between the two groups was not significant;The average plant height was 10.325 cm,which was significantly different from the previous two groups.The 2000 times solution of chelerythrine content of 40% pesticide produced 48.57% control effect on pepper blight,and the fresh weight of plants in this treatment group was 50.51% higher than that of the control group,and the dry weight was 28.93% higher than that of the control group.