Zeatin

Zeatin is a natural cytokinin, a class of plant hormones that promote cell division and shoot formation. It is a purine derivative with an isoprenoid side chain attached to the N6 position of adenine; naturally occurring forms include trans-zeatin (the most common active form) and cis-zeatin, which is found in some species. Zeatin was first isolated from Zea mays (maize) kernels, and its name derives from the maize plant.

Biosynthesis and metabolism: Zeatin is produced in plants by isoprenylation of adenosine monophosphate by isopentenyltransferases (IPTs) to form iP-type cytokinins, followed by hydroxylation by cytochrome P450 enzymes (CYP735A) to yield zeatin-type cytokinins. The side chain may be hydroxylated to form trans-zeatin. Cytokinins are inactivated by cytokinin oxidases/dehydrogenases (CKX), which regulate their levels in tissues.

Function: Zeatin regulates cell division, shoot initiation and growth, leaf expansion, and delays leaf senescence. It interacts with auxin signaling to influence organ development, and it participates in various developmental and physiological processes in plants.

Occurrence and applications: Zeatin occurs in many higher plants, especially seeds and young tissues, and is often present in tissue culture media to promote shoot proliferation. In plant biotechnology, zeatin is used to stimulate shoot formation from explants and to support tissue culture propagation, with activity dependent on concentration and context.