Cytokinins (CK) are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cellgrowth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence. Folke Skoog discovered their effects using coconut milk in the 1940s at the University of Wisconsin–Madison.[1]
There are two types of cytokinins: adenine-type cytokinins represented by kinetin, zeatin, and 6-benzylaminopurine, and phenylurea-type cytokinins like diphenylurea and thidiazuron (TDZ).[2] Most adenine-type cytokinins are synthesized in roots.[3] Cambium and other actively dividing tissues also synthesize cytokinins.[4] No phenylurea cytokinins have been found in plants.[5] Cytokinins participate in local and long-distance signalling, with the same transport mechanism as purines and nucleosides.[6] Typically, cytokinins are transported in the xylem.[3]
Cytokinins act in concert with auxin, another plant growth hormone. The two are complementary,[7] [8] having generally opposite effects.[3]
(Wikipedia accessed May 2022)
