Hormone Synthetic Pathways and Genes in Arabidopsis: Abscisic acid

Abscisic acid (ABA)

Abscisic acid (ABA: (S)-(+)-2-cis-ABA) was originally identified as the bioactive compounds that induce abscission or bud dormancy. However, contribution of ABA to these physiological responses has not been clearly demonstrated. Instead, studies using ABA-deficient mutants from several plant species revealed that this hormone is required for the induction and maintenance of seed dormancy, stomatal closure, and response to biotic and abiotic stresses. (R)-(-)-2-cis-ABA (generally termed (-)-ABA) is biologically active as an ABA analogue, but do not exist in plant tissues. (S)-(+)-2-trans-ABA (trans-ABA) has been detected from plant tissues but do not exhibit ABA activity. ABA is synthesized via carotenoids. The biosynthesis pathway after zeaxanthin formation is shown here.

Pathway map of Abscisic acid biosynthesis
[MS PowerPoint: 247KB]

Genes on the pathway

Gene name Locus name Description
ABA1/ZEP At5g67030 zeaxanthin epoxidase (ZEP)
ABA4 At1g67080 neoxanthin synthase (NSY)
NCED2 At4g18350 9-cis-epoxycarotenoid dioxigenase (NCED)
NCED3 At3g14440 9-cis-epoxycarotenoid dioxigenase (NCED)
NCED5 At1g30100 9-cis-epoxycarotenoid dioxigenase (NCED)
NCED6 At3g24220 9-cis-epoxycarotenoid dioxigenase (NCED)
NCED9 At1g78390 9-cis-epoxycarotenoid dioxigenase (NCED)
ABA2 At1g52340 xanthoxin dehydrogenase (XD)
AAO3 At2g27150 abscisic aldehyde oxidase (ABAO)
ABA3 At1g16540 molybdenum cofactor sulfurare
CYP707A1 At4g19230 ABA 8’-hydorxylase (ABA8ox)
CYP707A2 At2g29090 ABA 8’-hydorxylase (ABA8ox)
CYP707A3 At5g45340 ABA 8’-hydorxylase (ABA8ox)
CYP707A4 At3g19270 ABA 8’-hydorxylase (ABA8ox)
BG1 At1g52400 ABA glucosidase
RIKEN Plant Hormone Research Network - RIKEN Center for Sustainable Resource Science