Utilizes UDP-xylose as the sugar donor and catalyzes the formation of o-xylosylzeatin from zeatin. Does not act on UDP-glucose. UDP-alpha-D-xylose + zeatin = H(+) + O-beta-D-xylosylzeatin + UDP High level in young seeds, less in older seeds and very low in roots. Belongs to the UDP-glycosyltransferase family.