Mechanisms of Meyerozyma caribbica isolated from Tibetan soil to inhibit Aspergillus ochraceus on grapes

The use of yeast antagonists to suppress postharvest fruit diseases and reduce economic losses has been attracting widespread attentions. In this study, the effectiveness of Meyerozyma caribbica isolated from Tibet soils against Aspergillus ochraceus and underlying mechanisms were investigated. M. caribbica exhibited great resistances under adverse environment and could obviously inhibit the growth and ochratoxin A (OTA) production of A. ochraceus via mycelium destruction and down-regulation of gene expressions involved in OTA synthesis. Besides, when grapes inoculated with A. ochraceus, disease incidence was reduced by both M. caribbica and its produced volatile organic compounds (VOCs). M. caribbica enhanced grape resistance to A. ochraceus by increasing resistance-related enzyme activities and gene expressions. VOCs were identified with the main compounds including 3-methyl-1-butanol, oxirane,2,2,3-trimethyl and 2-methyl-1-propanol. Accumulation of endogenous gamma-aminobutyric acid (GABA) content was observed in grapes treated by yeast VOCs. Therefore, M. caribbica can be applied as a promising biocontrol agent for postharvest fruit loss control.