The volatile components from Bacillus cereus N4 can restrain brown rot of peach fruit by inhibiting sporulation of Monilinia fructicola and inducing disease resistance

Abstract

Brown rot caused by Monilinia fructicola is one major disease in harvested peach fruit. Natural volatile compounds (VOCs) produced by antagonistic microorganisms have good biocontrol effects on postharvest fungal diseases. The present study showed the VOCs of Bacillus cereus N4 isolated from the orchard soil could significantly inhibit the sporulation and mycelial growth of M. fructicola. The expression levels of MfRGS2, MfRGS3 and MfLTF2α, which are unfavorable to the sporulation of M. fructicola were significantly induced by the VOCs of B. cereus N4. Moreover, the expression levels of MfRGS1, MfRGS4, MfREG1, MfPPOA and MfOPT1, which are beneficial to the sporulation of M. fructicola were markedly repressed. After fumigated with the VOCs of B. cereus N4 then inoculated with M. fructicola, peach fruit exhibited markedly lower disease incidence and lesion diameter than the control. Moreover, the activity of CHI and the expression level of PpCHI and PpPR1 of the fruit were significantly improved. 3-methyl-1-butanol, s-methyl butanethioate and 2-methyl-2-(methylthio)propane were the main antifungal substances in the VOCs of B. cereus N4 identified by gas chromatograph-mass spectrometer (GC-MS). Overall, the study provides natural candidates antibacterial agent from a biocontrol agent B. cereus N4 to restrain brown rot of peach fruit caused by M. fructicola.