Cytokinins: Chemical nature, Biosynthesis, Bioassay, Physiological effects and Mode of action
Cytokinin:- > It is mostly found in the roots of plants. > Zeatin is the first natural cytokinin. > Examples:- i. Kinetin (6 – Furfuryl Amino Purine) ii. Zeatin iii. 2 – iP (2 – Iso Pentenyladenine) iv. BA or BAP (Benzyl Adenine or 6 – Benzyl Amino Purine) v. Adenine (Aminopurine) 1. Discovery of Cytokinins:- - Skoog, Miller and co-workers in 1955 isolate and identify kinetin, a highly-active cell division factor, from autoclaved herring sperm DNA. - In searching for naturally occurring cytokinins in plant tissues, Letham in 1963 isolated a cytokinin, zeatin, from immature corn kernels. - A “kinetin-like” factor isolated by Miller in 1961 was later also identified as zeatin. 2. Chemical nature of Cytokinins:- All the naturally-occurring cytokinins are substituted purines. The usual way of naming a cytokinin is to express it as a substituted 6-amino purine or as N6-substituted adenine. 3. Biosynthesis of Cytokinins:- > Cytokinin is synthesi...