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The Six Classes of Plant Hormones and Their Function

What are the six classes of plant hormones? How do they affect plant growth and development?
Describe their major functions and mention as to where they are produced in the plant.
Please include reference sites.

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The six classes of plant hormones are auxins, gibberellins,cytokinins,abscisic acid, ethylene and jasmonates - jasmonic acids.

1.Auxins are growth-regulating substances with the chemical name indole-3-acetic acid (IES). They are produced throughout the plant with higher concentrations in the growing tips such as the tip of coleoptiles, buds, growing tips of leaves and roots wherein it is synthesized by tryptophan. When present in lower concentrations, they bring about the elongation of the coleoptiles of shoot and roots. Higher concentrations inhibit the elongation of shoot and root. It is due to the stimulation of ethylene, a gaseous hydrocarbon and a plant hormone. Auxins are actively involved in inhibition or delay of abscission and retardation of senescence. They play an important role in accelerating cell division in the cambium, thus bringing about secondary thickening, development of ovary into fruit, initiation and maintenance of apical dominance, tropic movements, and parthenocarpy.

2.Gibberellins are chemically gibberellic acids. Gibberellins are found in abundance in young, expanding ...

Solution Summary

The six classes of plant hormones are auxins, gibberellins, cytokinins, abscisic acid, ethylene and jasmonates - jasmonic acids.