Abstract: The inhibitory effect of 2,4-epibrassionolide (EBR) treatment on gray mold disease caused by Botrytis cinerea in postharvest grape berries (Vitis vinifera L. × V. labrusca L. cv. ‘Kyoho’) and the possible mechanisms were investigated. Grapes were pretreated with 5 μmol/L EBR for 12 h, inoculated with B. cinerea, and then stored at 25 ℃ for 60 h. The results showed that EBR treatment effectively inhibited the occurrence of gray mold and the expansion of lesion diameter. Grapes pre-treated with EBR showed stronger and faster response to the challenge of pathogen inoculation compared with either treatment alone, which corresponded to a significant increase in the activities of defense-related enzymes including chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase as well as total phenols content (P < 0.05), the accumulation of H2O2 and higher activities of superoxide dismutase, catalase, ascorbate peroxidase, and significantly increased expression levels of defense-related genes like VvCHI、VvGNS and VvPAL-like (P < 0.05). In vitro experiment showed that EBR treatment could inhibit spore germination but had no influence on germ tube elongation of B. cinerea. These results suggest that EBR treatment can improve resistance against gray mold decay in grapes, which is closely associated with the priming of defense responses.

Key words: grape berries, 2,4-epibrassionolide, gene expression, induced resistance, priming