Gibberellin

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Gibberellin, one of the groups of hormones that influence the growth of plants. They are chemical substances that occur naturally in many plants and regulate various important functions, such as the elongation of flowering stems, the creation of proteins, and the germination of some plant seeds. Unlike auxins, which are plant hormones that form in the plant’s top shoots and flow downward to affect the growth of plant parts, gibberellins form in the seeds, young leaves, and plant roots before flowing upward into the stem.

Gibberellins were discovered in 1926 by Japanese scientists investigating foolish-seedling disease in rice. This disease caused rice shoots to grow extremely long without corresponding root growth. As a result, the seedlings did not flower and usually died before maturity. Foolish-seedling disease was traced to the fungus Gibberella fujikuroi, which produces substances now known as gibberellins. More than 50 different gibberellins have been isolated and identified; the most common is gibberellic acid. Scientists have developed chemical compounds, called growth substances, that are based on gibberellin hormones and can cause the elongation of flowering stems in certain plants during their growth period. These synthetic growth substances can also substitute for the natural hormone in plants where a genetic malfunction has blocked the production of gibberellins. Growth substances are also used to increase the yield and size of certain crops, such as seedless grapes.

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