Transport and Metabolism of Labelled Zeatin Applied to the Stems of Phaseolus vulgaris at Different Stages of Development

Abstract

Labelled zeatin applied to either the xylem or phloem regions of the stems of developing Phaseolus vulgaris L. plants was transported in a pattern which was in accordance with what appears to be the distribution of endogenous cytokinins in this plant. Available cytokinins seem to be transported to preferential sites which shift within the plants as they progress from a vegetative to a reproductive phase of growth. In the flowering and fruiting plants there was increased transport of phloem applied radioactivity to the reproductive organs. Metabolism of applied radioactive zeatin was considerably advanced in reproductive plants. Most of the recovered metabolites were of a polar nature suggesting either side-chain glucosylation and/or side-chain cleavage as the metabolic pathways.