Flavonol-specific transcription activator involved in the regulation of several genes of flavonoid biosynthesis. Activates the expression of CHS, CHI, F3H and FLS1. Controls flavonol biosynthesis mainly in the root (PubMed:17419845, PubMed:20731781). Confers tolerance to UV-B (PubMed:19895401). Expressed in stems and flower buds (PubMed:9839469). Expressed in seedlings, roots, cotyledons and apical meristems (PubMed:17419845). In seedlings, predominantly expressed in roots. Expressed predominantly in the root, in the vascular tissue of the hypocotyl-root transition zone and, at low levels, at the region of apical meristem and the apex of cotyledons. By nitrogen deficiency, sucrose and UV LIGHT (PubMed:17053893, PubMed:9839469). Triggered by HY5 in response to light and UV-B (PubMed:19895401). Reduced flavonols levels in roots. The double mutant myb12 myb111 and triple mutant myb11 myb12 myb111 accumulate less flavonols in roots, leaves, stems, inflorescence, and siliques. The double mutant myb11 myb12 is specifically altered in flavonols content of siliques and roots (PubMed:20731781). The triple mutant myb11 myb12 myb111 is impaired in flavonols biosynthesis and exhibits a reduced UV-B tolerance (PubMed:17419845, PubMed:19895401). Promotes flavonoid biosynthesis when expressed in tobacco (Nicotiana tabacum) and tomato (Solanum lycopersicum) through up-regulation of the biosynthetic genes. Tobacco plants exhibit increased insect (Spodoptera litura and Helicoverpa armigera) resistance due to enhanced accumulation of rutin.