Functional Insights into the RCC1 Gene Family and UVR8-Mediated Regulation of Anthocyanin Biosynthesis in Grapevine.

Grapevine (Vitis vinifera L.) is a key fruit crop affected by abiotic stresses such as salinity, drought, and temperature extremes. The Regulator of Chromosome Condensation 1 (RCC1) family, involved in regulating Ran GTPase activation, nucleocytoplasmic transport, and chromatin organization, has not been comprehensively characterized in grapevine. In this study, we identified 26 VvRCC1 genes, which were classified into five phylogenetic groups, and analyzed their distribution across the grapevine genome. These genes exhibited significant diversity in physicochemical properties, suggesting functional divergence. Expression profiling revealed distinct spatiotemporal patterns, indicating roles in both vegetative growth and reproductive development. Notably, several VvRCC1 genes showed differential responses to salinity, drought, and heat stress. Importantly, VvRCC1-17, identified as UVR8, was shown to regulate anthocyanin biosynthesis under UV-B exposure. OE-VvUVR8 transgenic grape calli exhibited increased anthocyanin accumulation, reflected in a distinct red coloration compared to wild-type calli. This finding links UVR8 to light signaling and pigmentation pathways in grapevine, providing the first comprehensive analysis of the RCC1 gene family in grapevine and highlighting VvRCC1-17 (UVR8) as a key regulator of UV-induced anthocyanin biosynthesis, offering insights into the molecular mechanisms of stress adaptation and pigment regulation.