Abscisic acid (ABA) is a sesquiterpene compound (C15) derived from C40 carotenoids. The immediate carotenoid precursors for ABA biosynthesis, 9-cis-violaxanthin and 9'-cis-neoxanthin, are produced from β-carotene by a series of hydroxylation, epoxidation, and isomerization reactions. Carotenoid hydroxylase deficient mutants contain severely reduced levels of violaxanthin and neoxanthin (
Physiologia Plantarum (2004) 122 (3) 314-320 [doi: 10.1111/j.1399-3054.2004.00409.x]
Effect of hydroxylated carotenoid deficiency on ABA accumulation in Arabidopsis.