Contributes to the last few anthocyanin biosynthetic steps. Converts cyanidin 3-O-glucoside to cyanidin 3-O-xylosyl(1->2)glucoside. Can use 3-O-glucosylated anthocyanidins/flavonols and uridine diphosphate (UDP)-xylose as substrates. an anthocyanidin 3-O-beta-D-glucoside + UDP-alpha-D-xylose = an anthocyanidin 3-O-beta-D-sambubioside + 2 H(+) + UDP Secondary metabolite biosynthesis; flavonoid biosynthesis. By sucrose and cytokinin. Induced by jasmonic acid (JA) in a COI1- and brassinosteroids-dependent manner. Strong reduction in anthocyanin accumulation. Belongs to the UDP-glycosyltransferase family.