The biocontrol effect of Sporidiobolus pararoseus Y16 against postharvest diseases in table grapes caused by Aspergillus niger and the possible mechanisms involved

Abstract

Fruits are vulnerable to pathogen infection caused by decay during growth and storage, which causes huge economic losses. The aim of this study was to investigate the biocontrol efficacy of the antagonistic yeast Sporidiobolus pararoseus Y16 in the control of Aspergillus niger decay, and natural decay of table grapes and the possible mechanisms involved. The results showed that S. pararoseus Y16 at different concentrations significantly inhibited A. niger decay of table grapes compared with the control. Besides, the population dynamics results showed that S. pararoseus Y16 could rapidly survive and proliferate in grape wounds or on grape surfaces at 20°C. Moreover, S. pararoseus Y16 treatment did not impair postharvest qualities of table grapes. Results also showed that treatment with S. pararoseus Y16 enhanced the enzyme activities of polyphenol oxidase (PPO), catalase (CAT), phenylalanine ammonia-lyase (PAL) and ascorbate peroxidase (APX) in table grapes. Furthermore, the gene expression levels of PPO, CAT, PAL and APX were increased by gene level verification. All these results indicated that S. pararoseus Y16 has great potential for development of commercial formulations to control postharvest pathogens on table grapes. These findings revealed that the enhanced gene expression and enzyme activities are the mechanisms involved in the biocontrol, while the yeast outcompeted the fungus for space and nutrients.