Metabolism of 8[14C]t-Zeatin in Soybean Callus

8e4C]t-Zeatin applied to soybean callus was rapidly metabolized by a number of metabolic steps. This resulted in the formation of predominantly polar metabolites. These metabolites were formed as a result of ribosylation, glucosylation, reduction and oxidation reactions. From the evidence available it is concluded that primary steps in the metabolism of applied zeatin involve ribosylation at the N9 position of the adenine ring and oxidation and reduction of its side chain. O-Glucosylation of zeatin and its metabolites apparently involves a secondary reac-tion concerned with the inactivation and/or storage of the respective compounds. It is pre-sently not possible to determine whether dihydrozeatin or 6-{2,3,4-trihydroxy-3-methylbutyl-amino}purine are functional components in the cell division response. Both are as active or more active than zeatin in the soybean callus bioassay.