CHI–GSE–Nano-ZnO coating delays grape postharvest deterioration by inhibiting excess ROS via MYB714-pSTS484-mediated resveratrol biosynthesis

Grape seed extract (GSE) is a natural polyphenolic compound with potent antioxidant activity. We developed a composite preservation coating material by combining GSE with nano-zinc oxide (Nano-ZnO) and chitosan (CHI), two widely used agents in postharvest preservation. The CHI-GSE-Nano-ZnO coating effectively inhibited postharvest decay and berry abscission while delaying quality deterioration in grapes. Treatment with the composite coating enhanced the activities of antioxidant enzymes (SOD, POD, CAT, and APX) while reducing oxidative stress markers (O 2 - , H 2 O 2 , and malondialdehyde), thereby mitigating ROS accumulation to preserve postharvest grape quality. To elucidate the underlying mechanism, transcriptome sequencing was conducted on ‘Kyoho’ grape samples collected 3, 6, and 9 days post-treatment with CHI, CHI-GSE, and CHI-GSE-Nano-ZnO. Transcriptomic profiling revealed upregulation of VvSTS484 , a pivotal stilbene synthase (STS)-encoding gene, in the CHI-GSE-Nano-ZnO group. Promoter analysis identified multiple MYB-binding cis-elements in VvSTS484 . Yeast one-hybrid and transient dual-luciferase assays demonstrated that the transcription factor VvMYB714 directly binds to four specific MBS motifs in the VvSTS484 promoter (MBS1, -410 to -416 bp; MBS2, -1201 to -1207 bp; MBS3, -1554 to-1560 bp; and MBS4, -1906 to -1912 bp). This molecular interaction activated VvSTS484 expression, leading to enhanced resveratrol biosynthesis that peaked at day 9 post-treatment. The elevated resveratrol level in the CHI-GSE-Nano-ZnO group aligned with reduced oxidative stress and delayed quality deterioration, consistent with its established role in enhancing plant stress tolerance. In conclusion, the CH-GSE-Nano-ZnO composite coating inhibits postharvest decay via the MYB- pSTS module, providing a theoretical basis for developing natural product-based preservation technologies for fruit and vegetables.