Gibberellin

Gibberellins (GAs) are plant hormones that regulate various developmental processes, including stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence. GAs are one of the longest-known classes of plant hormone. It is thought that the selective breeding (albeit unconscious) of crop strains that were deficient in GA synthesis was one of the key drivers of the "green revolution" in the 1960s, a revolution that is credited to have saved over a billion lives worldwide. The first inroads into the understanding of GAs were developments from the plant pathology field, with studies on the bakanae, or "foolish seedling" disease in rice. Foolish seedling disease causes a strong elongation of rice stems and leaves and eventually causes them to topple over. In 1926, Japanese scientist Eiichi Kurosawa identified that foolish seedling disease was caused by the fungus Gibberella fujikuroi. Later work at the University of Tokyo showed that a substance produced by this fungus triggered the symptoms of foolish seedling disease and they named this substance "gibberellin". The increased communication between Japan and the West following World War II enhanced the interest in gibberellin in the United Kingdom (UK) and the United States (US). Workers at Imperial Chemical Industries in the UK and the Department of Agriculture in the US both independently isolated gibberellic acid (with the Americans originally referring to the chemical as "gibberellin-X", before adopting the British name–the chemical is known as gibberellin A3 or GA3 in Japan) Knowledge of gibberellins spread around the world as the potential for its use on various commercially important plants became more obvious. For example, research that started at the University of California, Davis in the mid-1960s led to its commercial use on Thompson seedless table grapes throughout California by 1962. A known gibberellin biosynthesis inhibitor is paclobutrazol (PBZ), which in turn inhibits growth and induces early fruitset as well as seedset.