Gibberellin A plant elongation growth regulator

 

Gibberellin is a weakly acidic growth hormone. E.  Kurusawa discovered the active substance  from the filtrate of a fungi named Gibberella fujikuroi. This fungi  causes Bakanae disease in the rice plants.

GA3 was the first gibberellin to be isolated in its pure form and remains the most extensively studied. There are more than hundred gibberellins  reported from the different organisms such as fungi and the higher plants. 

👌👌Remember - Barley endosperm test and drop test are used as a bioassays of gibberellins

The major sites of gibberellin production in plants are Apical shoot buds, young leaves near the shoot tips, root tips and the developing seed. Mevalonic acids is derived from acetyl coenzyme. ThIs the precursor of synthesis of gibberellic acid. 

Describe this growth regulator is transported through simple diffusion as well as through the  conducting channel. 

Gibberellin hormone enhances seed germination by increasing the efficiency of synthesis of alpha -  amylase and thus overcomes dormancy. In photoblastic seeds that is lettuce seed germination occurs by application of gibberellin even in dark. When gibberellin is sprayed on the rosette  plant like cabbage there is Rapid expansion of internode  and flowers with long stock are produced. This phenomenon is called bolting

If gibberellin hormone is sprayed on a single gene dwarf plant, genetic dwarfism is overcome and the plant becomes long. This can be seen as maize, pea etc. On female plants male flowers are produced by the application of the gibberellin and thus it promotes maleness. They are also important  and potent parthenocarpic agents. Gibberelic  acid is used to speed up the malting process in brewers Industries. Spraying sugarcane crop with gibberellin increase the length of the stem thus  increase the yield as much as  20 tons per acre. Spraying Juvenile conifers with  gibberellin, increase the maturity period thus leading to early seed production.

Next Article : Cytokinin - chemical structure physiological function and uses





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