Tailored UV-A Irradiation and Callus Selection Enable Distinct Flavonoid Profile Production in Grape Cell Cultures

Plant cell culture represents a sustainable platform for the production of high-value natural products. Although ultraviolet A (UV-A) radiation is established as an inducer of phenylpropanoid metabolism, its precise regulatory role in downstream flavonoid biosynthesis within grape cells remains unclear. Using red and white-type callus derived from Vitis vinifera L. cv. Cabernet Sauvignon berry skins, we investigated the effects of UV-A treatments with two durations (45 min and 90 min) on flavonoid biosynthesis. Metabolite profiling demonstrated that UV-A predominantly promoted proanthocyanidin accumulation in white-type callus, while stimulating the global flavonoid pathway in a dose-dependent manner in red callus. Transcriptional analysis identified structural genes potentially governing flavonoid product channeling in both callus types under UV-A exposure. Weighted Gene Co-expression Network Analysis (WGCNA) constructed light-responsive regulatory modules, uncovering potential mechanisms coordinating flavonoid pathway gene expression in response to UV-A. These findings demonstrate how the interaction of callus-type and UV-A shapes flavonoid metabolic flux, providing insights into the regulation of plant cell culture metabolites.