9-cis-epoxycarotenoid dioxygenase

9-cis-epoxycarotenoid dioxygenase (NCED) is an enzyme that plays a crucial role in the biosynthesis of abscisic acid (ABA), a plant hormone involved in seed dormancy and environmental stress responses. This enzyme catalyzes the cleavage of 9-cis-epoxycarotenoids to produce xanthoxin, the precursor of ABA.

Function

The primary function of 9-cis-epoxycarotenoid dioxygenase is to regulate the biosynthesis of abscisic acid. This hormone plays a vital role in various plant physiological processes, including seed dormancy, germination, growth, and response to environmental stresses such as drought, salinity, and cold.

Structure

The structure of 9-cis-epoxycarotenoid dioxygenase is complex, with multiple domains that contribute to its function. The enzyme contains a Rieske (2Fe-2S) domain and a non-heme iron (II) dioxygenase domain, which are essential for its catalytic activity.

Role in Plant Stress Response

Under conditions of environmental stress, the production of ABA is increased, largely due to the activity of 9-cis-epoxycarotenoid dioxygenase. This increase in ABA triggers a series of physiological responses in the plant, including stomatal closure to reduce water loss, synthesis of stress proteins, and alteration of gene expression patterns.

See Also

• Abscisic Acid
• Enzyme
• Plant Hormones
• Stress Response