Gibber Ellin

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GIBBERLLIN


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DEFINITION

Gibberellins (GAs) are plant

hormones that regulate growth andinfluence various developmental

processes.
http://en.wikipedia.org/wiki/Plant_hormonehttp://en.wikipedia.org/wiki/Plant_hormonehttp://en.wikipedia.org/wiki/Biological_processhttp://en.wikipedia.org/wiki/Biological_processhttp://en.wikipedia.org/wiki/Biological_processhttp://en.wikipedia.org/wiki/Biological_processhttp://en.wikipedia.org/wiki/Plant_hormonehttp://en.wikipedia.org/wiki/Plant_hormonehttp://en.wikipedia.org/wiki/Biological_processhttp://en.wikipedia.org/wiki/Biological_processhttp://en.wikipedia.org/wiki/Plant_hormonehttp://en.wikipedia.org/wiki/Plant_hormone


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RECOGNITION

Gibberellin was first recognized in 1926 by a

Japanese scientist, Eiichi Kurosawa, studying

bakanae, the "foolish seedling" disease in rice.
http://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/w/index.php?title=Eiichi_Kurosawa&action=edit&redlink=1http://en.wikipedia.org/wiki/Bakanaehttp://en.wikipedia.org/wiki/Bakanaehttp://en.wikipedia.org/w/index.php?title=Eiichi_Kurosawa&action=edit&redlink=1http://en.wikipedia.org/wiki/Japan


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ISOLATION & NAMING It was first isolated in 1935 byTeijiro Yabuta and

Sumuki, from fungal strains (Gibberella fujikuroi)

provided by Kurosawa.Yabuta named the isolate as gibberellin.
http://en.wikipedia.org/w/index.php?title=Teijiro_Yabuta&action=edit&redlink=1http://en.wikipedia.org/wiki/Gibberella_fujikuroihttp://en.wikipedia.org/wiki/Gibberella_fujikuroihttp://en.wikipedia.org/wiki/Gibberella_fujikuroihttp://en.wikipedia.org/wiki/Gibberella_fujikuroihttp://en.wikipedia.org/w/index.php?title=Teijiro_Yabuta&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Teijiro_Yabuta&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Teijiro_Yabuta&action=edit&redlink=1


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PROPAGATION Interest in gibberellins outside of Japan began after

World War II. In the United States, the first

research was undertaken by a unit at CampDetrick in Maryland, via studying seedlings of thebean Vicia faba.[1] In the United Kingdom, work onisolating new types of gibberellin was undertaken

at Imperial Chemical Industries.
http://en.wikipedia.org/wiki/World_War_IIhttp://en.wikipedia.org/wiki/Fort_Detrickhttp://en.wikipedia.org/wiki/Fort_Detrickhttp://en.wikipedia.org/wiki/Vicia_fabahttp://en.wikipedia.org/wiki/Gibberellinhttp://en.wikipedia.org/wiki/Imperial_Chemical_Industrieshttp://en.wikipedia.org/wiki/Imperial_Chemical_Industrieshttp://en.wikipedia.org/wiki/Gibberellinhttp://en.wikipedia.org/wiki/Vicia_fabahttp://en.wikipedia.org/wiki/Vicia_fabahttp://en.wikipedia.org/wiki/Vicia_fabahttp://en.wikipedia.org/wiki/Fort_Detrickhttp://en.wikipedia.org/wiki/Fort_Detrickhttp://en.wikipedia.org/wiki/World_War_II


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SYNTHESIS

All known gibberellins are diterpenoid

acids that are synthesized by theterpenoid pathway in plastids and thenmodified in the endoplasmicreticulum and cytosol until they reachtheir biologically-active form.
http://en.wikipedia.org/wiki/Terpenoidhttp://en.wikipedia.org/wiki/Plastidhttp://en.wikipedia.org/wiki/Endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Cytosolhttp://en.wikipedia.org/wiki/Cytosolhttp://en.wikipedia.org/wiki/Endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Plastidhttp://en.wikipedia.org/wiki/Terpenoid


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NOMENCLATURE

The gibberellins are named

GA1 through GAn in order ofdiscovery. Gibberellic acid,

which was the first gibberellinto be structurallycharacterized, is GA3.
http://en.wikipedia.org/wiki/Gibberellic_acidhttp://en.wikipedia.org/wiki/Gibberellic_acidhttp://en.wikipedia.org/wiki/Gibberellic_acidhttp://en.wikipedia.org/wiki/Gibberellic_acid


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]

As of 2003, there were 126 GAs identified fromplants, fungi, and bacteria.

There are two classes based on the presence ofeither 19 or 20 carbons
http://en.wikipedia.org/wiki/Gibberellinhttp://en.wikipedia.org/wiki/Gibberellin


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Biological functions


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Stem elongation

Gibberellins cause stem elongation and leafexpansion. It is believed that certain types ofdwarfness are due to gibberellin deficiency. But ithas no effect on roots.


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Seed Germination

Gibberellins promote seed germination in lettuce,

cereals


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Breaking of seed dormancy

Gibberellins break dormancy of buds and tubers. Butin root tubers it inhibits the development of the roottuber.


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Parthenocarpy

Gibberellins cause parthenocarpy in apple and pear.


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Increasing Fruit Size

Gibberellins along with auxin, control the growth anddevelopment of fruits.


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Flowering and sex expression

Gibberellins control flowering in plants. Gibberellinspromote the production of male flowers, either inplace of female flowers in monoecious plants or ingenetically female plants such as cucurbits.


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Agricultural Applications of

Gibberellins


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Fruit growth and parthenocarpy

Increased yield (larger size) and better shape of grapesis obtained by treating the fruit bunches with GA. Itinduces parthenocarpy in apples, pears, tomatoes and

cucumbers.


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Delayed ripening

Gibberellins delay fruit maturity and senescence inlemons, oranges and cherries. This helps in storing thefruits.


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Flowering

Gibberellins help in the flowering of many plants.


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Breaking of Dormancy

Gibberellins treatment helps in breaking dormancy in

seed potatoes resulting in uniform crop emergence.

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