Review on Biosynthesis, Signal transduction of ABA and its Function in Physiological and Metabolic Process of Crop plants

Abstract

Abscisic acid (ABA) is a phytohormone that regulates physiological processes such as seed maturation, seed dormancy, and stress adaptation. These physiological responses are triggered by the fluctuation of endogenous ABA levels in accordance with changing surroundings or developmental stimuli. Endogenous ABA levels are largely controlled by the balance between biosynthesis and catabolism. ABA is produced by cleavage of a 40-carbon carotenoid precursor that is synthesized from isopentenyl diphosphate via the plastid terpenoid pathway. ABA is synthesized in almost all cells that contain plastids and is transported via both the xylem and the phloem. ABA in tissues can be measured by bioassays based on growth, germination, or stomatal closure. Abscisic acid plays primary regulatory roles in the initiation and maintenance of seed and bud dormancy and in the plant’s response to stress, particularly water stress.