Question

Write a brief account of abscisic acid.

Answer 1

Hint: Abscisic acid is a plant hormone .

Complete answer: Abscisic acid was discovered for its role in regulating abscission and dormancy but like other plant growth regulators, it also has other wide-ranging effects on plant growth and development.
1. It acts as a general plant growth inhibitor and an inhibitor of plant metabolism.
2. Abscisic acid inhibits seed germination.
3. Abscisic acid stimulates the closure of stomata in the epidermis and increases the tolerance of a plant to various kinds of stresses. Therefore it is also known as the stress hormone.
4. Abscisic acid plays an important role in seed development maturation and dormancy.
It induces dormancy and helps seeds to withstand desiccation and other factors unfavorable for growth.

Additional information: The plant growth regulators are small simple molecules of diverse chemical composition. They could be indole compounds, adenine derivatives, derivatives of carotenoids, terpenes, or gases.
Plant growth regulators are broadly classified into two groups one inhibitor and another promoter. Abscisic acid is an inhibitor plant growth regulator.

Note: Abscisic acid is antagonist to gibberellic acid .
Three independent researchers reported in mid-1960 the purification and chemical characteristics of three different kinds of inhibitors inhibitor-B, abscission II and domain later all the three were proved to be chemically identical it was named Abscisic acid.