Functions of cytokinins

Abstract

Mechanisms of action of cytokinins at the cellular and molecular levels are still unknown. Biological functions of cytokinins are presented through specific bioassay systems which are regarded as standard (delay of senescence of leaf tissue and stimulation of cell division) and which have been or may be biochemically investigated. These ‘biochemical functions’ of cytokinins are reviewed. The biochemical significance of the specific occurrence of cytokinins in transfer RNA molecules is discussed with respect to the question of the incorporation of labelled cytokinins into RNA molecules. Also, the significance of the cytokinin binding protein recently isolated from higher plant ribosomes is discussed.