Primary Study on the Inhibition Mechanism against Botrytis cinerea Pers. of Chitosan-oligosaccharides Obtained by Enzymatic Hydrolysis

Objective: In order to study the inhibition mechanism of the chitosanoligosaccharides prepared through enzymatic hydrolysis by chitosanase to Botrytis cinerea Pers.Method: The inhibition effects of the chitosan-oligosaccharides upon the hyphae and the spore germination of Botrytis cinerea Pers.were studied.And the morphology shape of hyphae,the cell membrane permeability of the pathogen and the content of soluble protein from Botrytis cinerea.treated with the chitosan-oligosaccharides were also investigated.Result: When the concentration of the chitosan-oligosaccharides was over 1.5mg/mL,the inhibition rate to the hypha growth of Botrytis cinerea Pers reached to over 70%,and the EC50 was 0.72mg/mL.When the concentration was 6mg/mL,the inhibition rate to the spore germination was more significant than the others,reached to 87.4%.The EC50 was 1.48mg/mL.According to the microscope observations,the chitosan-oligosaccharides with concentration of 8mg/mL induced morphological changes,including excessive branching and hyphal segments in the new hyphal of Botrytis cinerea Pers.The formation of conidiospore was inhibited.The chitosan-oligosaccharides could result in the leakage of inclusion of mycelium and in the change of permeability of the cell membrane so as to increase the conductivity.In addition,the inclusion of protein from the pathogen of B.cinerea declined 36.7% under the treatment of the chitosan-oligosaccharides for 66 hours.Conclusion: The research of chitosan-oligosaccharides' inhibition mechanism towards Botrytis cinerea Pers provides basis for the mechanism of chitosan-oligosaccharides,the new biological pesticide.