elongation, Germination and Fruit Matuartion
Gibberellin is created in the root and stemapical meristems, young leaves, and seed embryos. They stimulate stem and leaf growth by cell elongation and cell division. Although biologists are not 100% sure, evidence suggests that gibberellin activates enzymes that loosen cell walls and allow expansion proteins to enter the cell. Gibberellin works with the plant hormone, auxin, to achieve stem elongation. The hormone, abscisic acid, is an antagonist of gibberellin and instead, slows growth and inhibits germination.
The release of gibberellin by the embryo of a seed signals that the seed is ready to germinate and is no longer in a dormant state. Some plants can be manipulated and are able to break dormancy (even when under unfavorable conditions) if stimulated by gibberellin.
Gibberellin controls fruit growth and development by inducing the development of seedless fruits from unfertilized pistils (female plant organs), especially in the case of fruits such as apples and pears.
Gibberellin and Gene Expression
Gibberellin hormones can be extremely useful in the agricultural industry. For example, seedless grapes are often treated with gibberellin to create larger fruits, as well as longer stems which reduces mildew infection. Additionally, gibberellin can be used to ripen fruits, (such as lemons, oranges, and cherries) at specific times, which helps the market when certain fruits are out of season. Lastly, gibberellin treatment helps break dormancy in “seed potatoes” resulting in uniform crop emergence.