Short Term Metabolism of Different Concentrations of Zeatin Applied to Soybean Callus

Abstract

Summary The fate of zeatin when applied to soybean callus at a concentration which stimulates (10 -5 M), and a concentration which inhibits (10 -3 M) its growth, was investigated. In both instances metabolism was rapid, and during the first 24 h of incubation the major radioactive metabolite(s) formed (at both concentrations of zeatin) co-eluted with adenine. The overall rate of metabolism was slower over the 96 h experimental period when a high concentration of zeatin was applied to the callus. This could be due, in part, to an incapacity to deal with the large amount of hormone, but also to the different metabolites which were formed when a high concentration of zeatin was applied. To what extent the main product(s) formed, when zeatin is applied at a concentration of 10 -3 M, inhibits callus growth remains to be established. It is of importance that this metabolite(s) was not detected in appreciable amounts in callus being supplied with 10 -5 M zeatin, a concentration which is optimum for the growth of soybean callus.