• GABA enhanced biocontrol efficacy of S. pararoseus Y16 to Aspergillus rot of grapes. • GABA induced PPO, POD and PAL activities of grapes treated with S. pararoseus Y16. • GABA increased flavonoids, phenolic content of grapes treated with S. pararoseus Y16. • The expression levels of PPO , POD and PAL of grapes were increased. Aspergillus tubingensis is a fungal pathogen that can cause Aspergillus rot in grapes and produces ochratoxin A. This study investigated the effect of Gamma-aminobutyric acid (GABA) on the biocontrol efficacy of Sporidiobolus pararoseus Y16 against Aspergillus rot in postharvest grapes. The results showed that GABA- treated S. pararoseus Y16 had a better control effect on A. tubingensis in rot rate, rot diameter, spore germination rate, and germ tube length compared with S. pararoseus Y16 alone. After 5 d post-inoculation, the decay rates of control, S. pararoseus Y16 treated, and GABA-treated S. pararoseus Y16 were 100%, 52.78% and 16.67% in grapes, respectively. Moreover, GABA-treated S. pararoseus Y16 had a better growth rate and more stable reproduction than S. pararoseus Y16. In the growth dynamic experiment, GABA-treated S. pararoseus Y16 has a better growth rate and a more stable reproduction than S. pararoseus Y16, under both 4 °C and 20 °C. The GABA-treated S. pararoseus Y16 significantly enhanced grapes' resistance-related enzyme activities and gene expression. Importantly, GABA-treated S. pararoseus Y16 effectively increased the activities of PPO, POD, PAL and the content of total phenols and flavonoids in grapes. In conclusion, GABA could potentially improve the biocontrol efficiency of S. pararoseus Y16 against Aspergillus rot in grapes via altering the yeast's physiology and the grape's disease-resistance system. [ABSTRACT FROM AUTHOR]