Abstract
Abscisic acid (ABA) is a plant hormone that regulates numerous physiological responses including seed maturation, germination, and adaptive responses to drought stress. ABA metabolism (biosynthesis and catabolism) and signaling are regulated tightly in response to environmental and developmental cues. Therefore, mutants defective in its metabolism and signaling fail to properly perform seed maturation, germination, and stress responses. My research group has conducted genetic screening to isolate Arabidopsis mutants, which are able to germinate in the presence of GA biosynthesis inhibitor and of (-)-R-ABA, an ABA analog. These mutants include those defective in ABA biosynthesis enzyme or in transcription factors required for ABA-mediated transcription. We also identified that CYP707A genes encode ABA 8'-hydroxylase, which catalyzes the committed step in a major ABA catabolic pathway. We showed that ABA catabolism is regulated by light, nutrient, drought, and submergence as well as to other plant hormones. Furthermore, identifying the cell types for activation of ABA biosynthesis and catabolism genes indicates that ABA-mediated response is systemic. I acknowledge my colleagues and collaborators involved in these studies.
