Antifungal Activities Of Volatile Compounds And Component Analysis Of Volatile Compounds Produced By Endophytic Bacillus Subtilis Y8 Against Curvularia Lunata

Curvularia lunata has become a damaging pathogenic fungus that threatens crop yield and people’s health.Maize leaf spot disease caused by Curvularia lunata caused seriously affected the yield and quality of maize.The disease also began to get people’s attention.Biological control has become a development direction of controlling plant diseases and insect pests.Previous studies have shown that Baeillus is a class of beneficial bacteria that can promote plant growth or antagonize pathogens.By generating volatility Substances can promote plant growth,control plant pathogens,and improve plant systemic resistance.At present,most of the studies on the volatile compounds of Bacillus spp,which exist in the plant surface,are concentrated in the Bacillus spp.The volatile compounds are easily diffused into the air and are not easy to accumulate to the effective concentration,so the stability of the application effect is poor.The volatile compounds produced by endophytic spores are more likely to accumulate to the effective concentration in a narrow space.Therefore,the bacteriostatic activity of volatile compounds of Bacillus subtilis Y8 was studied.On this basis,this study intends to make use of SPME-GC-MS technology is used to analyze the components of volatile compounds produced by Bacillus subtilis Y8,and the components with antibacterial activity are screened from the volatile compounds.The effect of the antibacterial components on the hypha structure of the Curvularia lunata is observed by scanning electron microscope and transmission electron microscope,and the effect of the antibacterial components on the pathogenic force of the Curvularia lunata is investigated;The pathogenic correlation and the expression of cell wall related genes were detected by fluorescence quantitative PCR.The results of the study are as follows:1.The volatile organic compounds(VOCs)produced by endophytic Bacillus subtilis Y8 had a strong antagonistic activity against C.lunata.2.The conjoint analysis of SPME-GC-MS and antagonistic experiment demonstrated that three VOCs including 2-methylbutyric acid5 2-heptanone and isopentyl acetate were responsible for the antifungal activities.3.Mieroscopic observations revealed that the three VOCs did not cause any morphological changes in mycelium and conidia when cultured with or without H2O2.4.However,all the three VOCs had a strong inhibition effect on the production of conidia,meanwhile 2-heptanone and isopentyl acetate inhibited the germination of conidia.5.In addition,the isopentyl acetate treatment strongly enhanced the accumulation of intracellular reactive oxygen species in conidia,which was harmful to C.lunata.Due to these negative effects,the three VOCs treatments finally reduced the pathogenicity of C.lunata.This study describes the significance and effectiveness of VOCs produced by an endophytic bacteria strain against C.lunata.