Abscisic acid

Abscisic Acid (ABA) is a plant hormone that plays a crucial role in plant growth and development. It is involved in various physiological processes such as seed dormancy, germination, and adaptation to environmental stresses.

Chemical Structure

Abscisic Acid is a sesquiterpene, which means it is composed of three isoprene units. It has a 15-carbon skeleton with a five-ring structure. The chemical formula of ABA is C15H20O4.

Biosynthesis

The biosynthesis of Abscisic Acid involves the mevalonic acid pathway in the chloroplasts. The process begins with the conversion of glucose to pyruvate, which is then converted to isopentenyl pyrophosphate (IPP). IPP is the precursor for the synthesis of all isoprenoids, including ABA.

Function

Abscisic Acid has several functions in plants. It regulates the closure of stomata in response to environmental stress conditions such as drought and high salinity. It also controls seed dormancy and germination by inhibiting the growth of the embryo. In addition, ABA plays a role in the regulation of plant growth and development by interacting with other plant hormones such as auxins, gibberellins, and cytokinins.

Role in Stress Tolerance

Abscisic Acid is known for its role in plant stress tolerance. It is produced in response to stress conditions such as drought, high salinity, and cold temperatures. ABA triggers the closure of stomata, reducing water loss and helping the plant to conserve water. It also induces the expression of stress-responsive genes, enhancing the plant's tolerance to stress conditions.

See Also

• Plant hormones
• Stomata
• Seed dormancy
• Stress tolerance in plants