AskDefine | Define gibberellin

Dictionary Definition

gibberellin n : a plant hormone isolated from a fungus; used in promoting plant growth

User Contributed Dictionary

English

Noun

  1. Any of a class of diterpene plant growth hormones first isolated from the fungus Gibberella fujikuroi.

Extensive Definition

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."
Gibberellin was first recognized in 1926 by a Japanese scientist, Eiichi Kurosawa, studying bakanae, the "foolish seedling" disease in rice. It was first isolated in 1935 by Teijiro Yabuta, from fungal strains (Gibberella fujikuroi) provided by Kurosawa. A known opponent to gibberellin is Paclobutrazol(PBZ), which in turn is growth inhibiting and inducing early fruitset as well as seedset.

Chemistry

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-kaurene. The gibberellins are named GA1....GAn in order of discovery. Gibberellic acid, which was the first gibberellin to be structurally characterised, is GA3.
As of 2003 there were 126 GAs identified from plants, fungi and bacteria.
Gibberellins are produced in greater mass when it’s cold. They stimulate cell elongation, breaking and budding, seedless fruits, and seed germination. They do the last by breaking the seed’s dormancy and acting as a chemical messenger. Its hormone binds to a receptor and Ca+2 activates a protein, calmodulin, and the complex binds to DNA, producing an enzyme to stimulate growth in the embryo.

References

gibberellin in Czech: Giberelin
gibberellin in Danish: Gibberellin
gibberellin in German: Gibberelline
gibberellin in Spanish: Giberelina
gibberellin in French: Gibbérelline
gibberellin in Italian: Gibberellina
gibberellin in Hebrew: ג'יברלין
gibberellin in Dutch: Gibberelline
gibberellin in Japanese: ジベレリン
gibberellin in Polish: Gibereliny
gibberellin in Russian: Гиббереллины
gibberellin in Slovak: Giberelín
gibberellin in Vietnamese: Gibberellin
gibberellin in Turkish: Gibberellin
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