Genome-wide identification and analysis of the jasmonic acid biosynthetic and signaling gene families in grapevine and the functional verification of VvLOX9 in resistance to cold.

Jasmonic acid (JA) biosynthesis and signaling genes are crucial for plant adaptation to environmental stress, but their systematic characterization and functional roles in cold stress tolerance in grapevine (Vitis vinifera) remain largely unclear. In this study, we identified 62 JA-related genes in grapevine, including five allene oxide synthase (AOS), two allene oxide cyclase (AOC), 16 lipoxygenase (LOX), 11 12-oxophytodienoate reductase (OPR), seven coronatine-insensitive 1 (COI1), 11 myelocytomatosis (MYC), and 10 jasmonate ZIM-domain (JAZ). Their physicochemical properties, phylogeny, chromosomal locations, duplication patterns, conserved sequences, gene structure, motifs, cis-acting elements, and tissue-specific expression were analyzed. Phylogenetic analysis showed that all JA-related gene families (except VvAOCs) clustered into three distinct groups, with genes of similar structural features grouping closely-supporting functional conservation within subclades. Evolutionary analysis indicated that segmental duplication was the major driver for the expansion of VvLOX, VvAOC, VvAOS, and VvJAZ families. Cis-acting elements and expression patterns analysis using RNA-seq and RT-qPCR demonstrated that VvMYC, VvJAZ, VvLOX, VvAOC, VvAOS, and VvJAZ genes were involved in abiotic stress responses. Given its strong induction under cold stress, VvLOX9 was isolated from 'Cabernet Sauvignon'. Transient transformation assays in grapevine leaves demonstrated that VvLOX9 positively regulates cold tolerance by promoting JA accumulation. Furthermore, transient transformation, yeast one-hybrid and dual-luciferase reporter assays demonstrated that the cold-responsive transcription factor VvERF10 directly binds to the CCGAC cis-element in the VvLOX9 promoter and activates its expression. This study provides mechanistic insights into JA-mediated cold response and offers valuable genetic resources for grape cold-tolerant breeding.