In enzymology, a zeatin O-beta-D-xylosyltransferase (EC 2.4.2.40) is an enzyme that catalyzes the chemical reaction

UDP-D-xylose + zeatin ${\displaystyle \rightleftharpoons }$ UDP + O-beta-D-xylosylzeatin

Thus, the two substrates of this enzyme are UDP-D-xylose and zeatin, whereas its two products are UDP and O-beta-D-xylosylzeatin.

This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is UDP-D-xylose:zeatin O-beta-D-xylosyltransferase. Other names in common use include uridine diphosphoxylose-zeatin xylosyltransferase, and zeatin O-xylosyltransferase.

• Turner JE, Mok DW, Mok MC, Shaw G (1987). "Isolation and partial purification of an enzyme catalyzing the formation of O-xylosylzeatin in Phaseolus vulgaris embryos". Proc. Natl. Acad. Sci. U.S.A. 84 (11): 3714–3717. doi:10.1073/pnas.84.11.3714. PMC 304946. PMID 16593839.