Transport and Metabolism of Labelled Zeatin Applied to the Primary Leaves of Fruiting Phaseolus vulgaris Plants

Labelled zeatin applied to the primary leaves of fruiting Phaseolus vulgaris plants was metabolized rapidly and extensively. After ten days the major metabolite detected in the leaves co-chromatographed with glucosylzeatin. No evidence could be found that this metabolite was exported to the developing fruits. From the available evidence it would appear that when compounds were exported from the primary leaves they were converted to a polar compound which was retained on Dowex 50 cation exchange resin and which co-eluted with N-(purin-6-yl)glycine. This was the only metabolite detected in the developing fruits. In all cases it represented less than 1% of the total radioactivity recovered from the plants. The results obtained suggest that cytokinin glucosides are stable metabolites which are not readily exported from the mature primary leaves of bean plants.