Catalyzes the glycosylation of flavonoids from UDP-glucose. Uses a wide range of flavonoid substrates including flavonols (quercetin, kaempferol, isorhamnetin, 3-OH 7,2',4'-MeO-flavone), flavones (luteolin, apigenin), flavanones (naringenin, hesperetin), flavanonols (taxifolin), isoflavones (genistein, daidzein), flavonol glycosides (quercitrin, isoquercitrin, rutin), and chalcones (isoliquiritigenin). Specific for the C-7 position, with a 20-fold lower activity for the C-3 position. a 7-O-hydroxy-flavonol + UDP-alpha-D-glucose = a flavonol 7-O-beta-D-glucoside + H(+) + UDP Secondary metabolite biosynthesis; flavonoid biosynthesis. A number of isoforms are produced. According to EST sequences. Expressed in roots and flowers. Not induced by salicylic acid. Belongs to the UDP-glycosyltransferase family.