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Gibberellins (GAs) are plant hormones that regulate growth and influence various developmental processes, including stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, and leaf and fruit senescence. 〔(Gibberellins: A Short History ), from http://www.plant-hormones.info, the home since 2003 of a website developed by the now-closed Long Ashton Research Station〕 Gibberellin was first recognized in 1926 by a Japanese scientist, Eiichi Kurosawa, studying ''bakanae'', the "foolish seedling" disease in rice.〔〔(Phytohormones (Plant Hormones) and other Growth Regulators: Gibberellin ), from a University of Hamburg website〕 It was first isolated in 1935 by Teijiro Yabuta and Sumuki, from fungal strains (''Gibberella fujikuroi'') provided by Kurosawa.〔 Yabuta named the isolate as gibberellin.〔 Interest in gibberellins outside of Japan began after World War II. In the United States, the first research was undertaken by a unit at Camp Detrick in Maryland, via studying seedlings of the bean ''Vicia faba''.〔 In the United Kingdom, work on isolating new types of gibberellin was undertaken at Imperial Chemical Industries.〔 Interest in 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.〔(Gibberellin and Flame Seedless Grapes ) from a University of California, Davis website〕 A known antagonist to gibberellin is paclobutrazol (PBZ), which in turn inhibits growth and induces early fruitset as well as seedset. ==Chemistry== 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.〔Campbell, Neil A., and Jane B. Reece. ''Biology''. 6th ed. San Francisco: Benjamin Cummings, 2002.〕 All gibberellins are derived via the ''ent''-gibberellane skeleton, but are synthesised via ''ent''-kaurene. The gibberellins are named GA1 through GAn in order of discovery. Gibberellic acid, which was the first gibberellin to be structurally characterized, is GA3. As of 2003, there were 126 GAs identified from plants, fungi, and bacteria.〔 Gibberellins are tetracyclic diterpene acids. There are two classes based on the presence of either 19 or 20 carbons. The 19-carbon gibberellins, such as gibberellic acid, have lost carbon 20 and, in place, possess a five-member lactone bridge that links carbons 4 and 10. The 19-carbon forms are, in general, the biologically active forms of gibberellins. Hydroxylation also has a great effect on the biological activity of the gibberellin. In general, the most biologically active compounds are dihydroxylated gibberellins, which possess hydroxyl groups on both carbon 3 and carbon 13. Gibberellic acid is a dihydroxylated gibberellin. Image:Gibberellin A1.svg| Image:Gibberellic acid.svg| Image:Ent-Gibberellane.svg| Image:Ent-Kauren.svg| 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gibberellin」の詳細全文を読む スポンサード リンク
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