Cytokinins

c. Cytokinin : Cytokinins are growth hormones that specifically promote cell division; the name was coined by Letham. The first cytokinin was discovered by Skoog and Miller in 1954 while investigating the nutritional requirements of tobacco (Nicotiana tabacum) callus tissue culture -- they found that callus proliferated when the culture medium was supplemented with coconut milk and a degraded sample of herring-sperm DNA, and named the active compound kinetin. Chemically, kinins are 6-furfurylaminopurine derivatives. The first cytokinin found naturally in plants, isolated from unripe maize grains by Letham and co-workers, was named zeatin; 6-benzyladenine is a widely used synthetic cytokinin. Seven distinct natural cytokinins have been recorded from plants, including from banana flowers and apple and tomato fruits. …