May regulate active versus storage forms of cytokinins, and could have an impact on seed growth. Can also use UDP-xylose to catalyze the formation of O-xylosylzeatin but at much lower affinity. trans-zeatin + UDP-alpha-D-glucose = H(+) + O-beta-D-glucosyl-trans-zeatin + UDP Belongs to the UDP-glycosyltransferase family.