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.
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Claims 12
Claim · model-written summary
ABA2 overexpressors had elevated ABA levels.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae2 - Gene
- ABA2e0
- Outcome
- elevated ABA levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ABA2-overexpressing transgenic plants with elevated ABA levels”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
ABA2 overexpressors showed delayed seed germination relative to wild type.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Organ / stage
- seede0
- Treatment
- ABA2-overexpressinge0
- Gene
- ABA2e0
- Outcome
- seed germination delaye0
- Direction
- delaye0
- Comparator
- wild typee0
- Setting
- agar plates and/or in soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
ABA2 overexpressors had greater salinity tolerance than wild type.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Treatment
- ABA2-overexpressinge0
- Gene
- ABA2e0
- Outcome
- tolerance to salinitye0
- Direction
- moree0
- Comparator
- wild typee0
- Setting
- agar plates and/or in soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
At 250 mm NaCl, germination delay disappeared in high ABA transgenics.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Outcome
- germination delay was abolishede0
- Value
- over 2-folde0
- Qualifier
- ABA levels over 2-fold higher than that of wild type grown on 250 mm NaCle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Exogenous ABA restored normal root growth in aba2 mutants.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Material
- aba2e0
- Organ / stage
- primary roote0
- Treatment
- exogenous application of ABAe0
- Outcome
- normal root growthe0
- Direction
- restorede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The ABA-deficient mutant aba2, with a shorter primary root, can be restored to normal root growth by exogenous application of ABA”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
ABA2 overexpressors retained normal root growth.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Organ / stage
- roote0
- Gene
- ABA2e0
- Outcome
- normal root growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transgenic plants overexpressing ABA2 showed normal root growth”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Prolonged stresses enhanced ABA2 promoter activity.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Treatment
- multiple prolonged stresses, such as drought, salinity, cold, and floodinge0
- Gene
- ABA2e1
- Outcome
- promoter activitye0
- Direction
- enhancede0
- Comparator
- short-term stress treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the promoter activity was enhanced by multiple prolonged stresses, such as drought, salinity, cold, and flooding, but not by short-term stress treatments.”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
e1“ABA2 promoter activity”
Claim · model-written summary
Short term stresses did not enhance ABA2 promoter activity.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Treatment
- short-term stress treatmentse0
- Gene
- ABA2e1
- Outcome
- promoter activitye0
- Direction
- note0
- Comparator
- multiple prolonged stressese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the promoter activity was enhanced by multiple prolonged stresses, such as drought, salinity, cold, and flooding, but not by short-term stress treatments.”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
e1“ABA2 promoter activity”
Claim · model-written summary
Prolonged drought upregulated ABA biosynthetic genes.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Treatment
- prolonged drought stress treatmente0
- Gene
- ABA biosynthetice0
- Outcome
- up-regulation of ABA biosynthetice0
- Direction
- up-regulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“prolonged drought stress treatment led to the up-regulation of ABA biosynthetic and sugar-related genes.”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Prolonged drought upregulated sugar-related genes.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Treatment
- prolonged drought stress treatmente0
- Gene
- sugar-related genese0
- Outcome
- sugar-related genese0
- Direction
- up-regulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“prolonged drought stress treatment led to the up-regulation of ABA biosynthetic and sugar-related genes.”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Basal ABA is interpreted as essential for normal primary root elongation.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Organ / stage
- primary roote0
- Compound
- ABAe0
- Outcome
- normal primary root elongatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the basal levels of ABA are essential for maintaining normal primary root elongation.”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
ABA2 may fine tune ABA biosynthesis through primary metabolic changes under stress.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae2
- Gene
- ABA2e0
- Outcome
- ABA biosynthesise0
- Qualifier
- through primary metabolic changes in response to stresse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“Arabidopsis”
e2“Arabidopsis (Arabidopsis thaliana)”
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