Cytokinins were discovered as

Step-by-step solution

Kinetin (a modified form of adenine, a purine) is obtained from the autoclaved herring sperm DNA. Kinetin does not occur naturally in plants. Search for natural substances with cytokinin-like activities led to the isolation of zeatin from corn-kernels and coconut milk. Since the discovery of zeatin, several naturally occurring cytokinins and some synthetic compounds with cell division promoting activity have been identified. Natural cytokinins are synthesized in regions where rapid cell division occurs, for example