Origin of Cytokinins Transported in the Phloem

Abstract

Abstract The origin of cytokinins in the exudate of Yucca inflorescences has been studied. A decrease in nucleotides of both isopenlenyladenine and zeatin was observed after removal of leaves as measured over a three day period. Removal of roots and the greater part of the rhizome resulted in a transient decline of isopenlenyladenincand zeatin nucleotides during 24 h. after which an increase took place. The results strongly indicate that the latter increase is due to cytokinins originating from the leaves.