Gibberellin

Gibberellins (GAs) are plant hormones involved in promotion of stem elongation, mobilization of food reserves in seeds and other processes. Its absence results in the dwarfism of some plant varieties. Chemically all known gibberellins are diterpenoid acids that are synthesized by the terpenoid pathway in plastids and then modified in the endoplasmic reticulum and cytosol until they reach their biologically-active form. All gibberellins are derived from the ent-gibberellane skeleton, but are synthesised via ent-kauren. The gibberellins are named GA1....GAn in order of discovery. Gibberellic acid, which was the first gibberellin to be structurally characterised, is GA3. There are currently 136 GAs identified from plants, fungi and bacteria.

Much of our knowledge of the biosynthesis and molecular mechanisms of gibberellins comes from research on their role in triggering α-amylase release by the aleurone layer in seed germination. Gibberellin was first isolated in 1935 by Japanese scientist, Teijiro Yabuta (1888-1977) from the fungus Gibberella fujikuroi.