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Ectopic expression of ABSCISIC ACID 2/GLUCOSE INSENSITIVE 1 in Arabidopsis promotes seed dormancy and stress tolerance.
- Source :
-
Plant physiology [Plant Physiol] 2007 Feb; Vol. 143 (2), pp. 745-58. Date of Electronic Publication: 2006 Dec 22. - Publication Year :
- 2007
-
Abstract
- Abscisic acid (ABA) is an important phytohormone that plays a critical role in seed development, dormancy, and stress tolerance. 9-cis-Epoxycarotenoid dioxygenase is the key enzyme controlling ABA biosynthesis and stress tolerance. In this study, we investigated the effect of ectopic expression of another ABA biosynthesis gene, ABA2 (or GLUCOSE INSENSITIVE 1 [GIN1]) encoding a short-chain dehydrogenase/reductase in Arabidopsis (Arabidopsis thaliana). We show that ABA2-overexpressing transgenic plants with elevated ABA levels exhibited seed germination delay and more tolerance to salinity than wild type when grown on agar plates and/or in soil. However, the germination delay was abolished in transgenic plants showing ABA levels over 2-fold higher than that of wild type grown on 250 mm NaCl. The data suggest that there are distinct mechanisms underlying ABA-mediated inhibition of seed germination under diverse stress. The ABA-deficient mutant aba2, with a shorter primary root, can be restored to normal root growth by exogenous application of ABA, whereas transgenic plants overexpressing ABA2 showed normal root growth. The data reflect that the basal levels of ABA are essential for maintaining normal primary root elongation. Furthermore, analysis of ABA2 promoter activity with ABA2::beta-glucuronidase transgenic plants revealed that the promoter activity was enhanced by multiple prolonged stresses, such as drought, salinity, cold, and flooding, but not by short-term stress treatments. Coincidently, prolonged drought stress treatment led to the up-regulation of ABA biosynthetic and sugar-related genes. Thus, the data support ABA2 as a late expression gene that might have a fine-tuning function in mediating ABA biosynthesis through primary metabolic changes in response to stress.
- Subjects :
- Abscisic Acid biosynthesis
Arabidopsis drug effects
Arabidopsis growth & development
Carbohydrate Metabolism physiology
Gene Expression Regulation, Plant drug effects
Germination
Plants, Genetically Modified
Seedlings growth & development
Seedlings metabolism
Seeds drug effects
Seeds growth & development
Sodium Chloride pharmacology
Up-Regulation
Alcohol Oxidoreductases genetics
Alcohol Oxidoreductases metabolism
Arabidopsis metabolism
Arabidopsis Proteins genetics
Arabidopsis Proteins metabolism
Gene Expression drug effects
Seeds metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0032-0889
- Volume :
- 143
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Plant physiology
- Publication Type :
- Academic Journal
- Accession number :
- 17189333
- Full Text :
- https://doi.org/10.1104/pp.106.084103