Carotenoid cleavage dioxygenases and their apocarotenoid products in plants

Abstract

Carotenoid cleavage dioxygenases (CCDs) catalyze the cleavage of carotenoids in various organisms. In Arabidopsis, the CCD enzyme family consists of nine members, which are further divided into two subfamilies: five 9-cis epoxycarotenoid dioxygenases (NCEDs) and four CCDs. The NCEDs are involved in the biosynthesis of the plant hormone abscisic acid (ABA). CCDs are only distantly related to the NCEDs, and their substrate specificities and activities differ from those of the NCEDs. Recent evidence indicates that apocarotenoids produced by the action of CCDs play various roles in the growth and development of plants; these apocarotenoids include a novel plant hormone that controls shoot branching and pollinator attractants produced in reproductive organs. This review focuses on enzymes belonging to the CCD subfamily; their enzymatic activities and the functions of their apocarotenoid products are discussed.