Lineage-specific diversification and tissue-specialized jasmonate defense roles of OPR genes in tea (Camellia sinensis).

Defense-associated gene families in long-lived perennials evolve under continuous biotic pressure, yet the forces shaping their diversification and tissue-specialized roles remain poorly understood. Here, we provide the first comprehensive evolutionary and regulatory analysis of the 12-oxo-phytodienoate reductase (OPR) gene family in tea (Camellia sinensis), a woody perennial that experiences recurrent herbivory and pathogen attacks. Through an integrative framework combining genome-wide identification, phylogenetics, gene structure and motif analyses, cis-regulatory profiling, selective pressure estimation, multi-stress transcriptomics, and RT-qPCR validation, we identified seven CsOPR genes grouped into three well-supported lineages. All CsOPRs retain conserved FMN-binding residues, while localized motif divergence, including the loss of motif 2 in CsOPR3 suggests potential subfunctionalization under strong purifying selection. Promoter composition reveals extensive jasmonate-abscisic acid-light cross-regulation, consistent with tissue-specific stress responses: CsOPR1/2 function as strongly associated with foliar defense, whereas CsOPR7 displays root-biased and stress-modulated expression. Multi-predictor subcellular localization analyses suggest putative vacuolar or endomembrane association for several CsOPRs, pending experimental validation. Collectively, this study establishes a high-resolution framework for OPR evolution and regulatory innovation in tea and identifies structurally divergent, stress-responsive members as high-priority targets for functional genomics. These insights advance understanding of how perennial species tailor jasmonate-mediated defense across tissues and provide molecular entry points for breeding strategies aimed at strengthening biotic stress resilience in long-lived crops.