Light quality affects flavonoid biosynthesis in young berries of Cabernet Sauvignon grape

► Visible light induces biosynthesis of proanthocyanidins in young grape skins. ► Visible light increases the level of B-ring hydroxylation of proanthocyanidins. ► UV light specifically induces biosynthesis of flavonol. ► The decrease in proanthocyanidin biosynthesis by light exclusion is limited. ► Members of a MYB transcription factor family are regulated differently by light.