MeJA (Methyl jasmonate) acts as a crucial regulatory phytohormone that mediates plant responses to biotic and abiotic stresses. Nevertheless, systematic studies on the effects and underlying regulatory mechanisms of MeJA on the postharvest quality of table grapes during low-temperature storage remain limited. In this study, physiological measurements combined with transcriptomic data demonstrated that MeJA treatment effectively maintained the postharvest quality of ‘Kyoho’ grapes under low-temperature storage. Physiological results showed that MeJA significantly enhanced the activities of antioxidant enzymes, inhibited the activities of cell wall softening-related enzymes PG and PE, promoted lignin accumulation, and delayed cellulose degradation. Furthermore, transcriptomic analysis verified that MeJA markedly upregulated the expression of genes associated with lignin biosynthesis. Collectively, MeJA maintains the postharvest quality of ‘Kyoho’ grapes during low-temperature storage by modulating antioxidant metabolism and cell wall metabolism, exhibiting great potential as an effective postharvest regulatory technique.

Grapes are among the most widely cultivated fruit crops globally, yet their growth and yield are severely compromised by Colletotrichum viniferum, which causes a devastating disease that affects grape berries. The wall-associated kinase (WAK) gene family, a unique subfamily of receptor-like-kinases (RLKs), plays important roles in mediating plant responses to both abiotic and biotic stresses. However, the expression patterns and biological functions of grape WAKs in response to C. viniferum infection remain largely uncharacterized. In this study, a total of 57 VdWAK genes were identified and phylogenetically classified into twelve subgroups. Chromosomal localization and collinearity analyses further revealed that tandem duplication and segmental duplication events contributed to the expansion of the VdWAK gene family. Transcriptomic profiling identified VdWAK19 as a key responsive gene. It was predominantly expressed in mature berries but transcriptionally repressed upon C. viniferum infection. Virus-induced gene silencing assays in grape berries demonstrated that knockdown of VdWAK19 significantly reduced fruit resistance to C. viniferum infection. Overall, these findings advance our understanding of the functional roles of VdWAK genes during C. viniferum infection and provide a theoretical basis for the potential application of VdWAK19 in breeding grape varieties with enhanced resistance to ripe rot.