Abstract
Plant stomata play an important role in CO2 uptake for photosynthesis and transpiration, but the mechanisms underlying stomatal opening and closing under changing environmental conditions are still not completely understood. Through large-scale genetic screening, we isolated an Arabidopsis mutant (closed stomata2 (cst2)) that is defective in stomatal opening. We cloned the causal gene (MGR1/CST2) and functionally characterized this gene. The mutant phenotype was caused by a mutation in a gene encoding an unknown protein with similarities to the human magnesium (Mg2+) efflux transporter ACDP/CNNM. MGR1/CST2 was localized to the tonoplast and showed transport activity for Mg2+. This protein was constitutively and highly expressed in guard cells. Knockout of this gene resulted in stomatal closing, decreased photosynthesis and growth retardation, especially under high Mg2+ conditions, while overexpression of this gene increased stomatal opening and tolerance to high Mg2+ concentrations. Furthermore, guard cell-specific expression of MGR1/CST2 in the mutant partially restored its stomatal opening. Our results indicate that MGR1/CST2 expression in the leaf guard cells plays an important role in maintaining cytosolic Mg2+ concentrations through sequestering Mg2+ into vacuoles, which is required for stomatal opening, especially under high Mg2+ conditions.
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Claims 9
Claim · model-written summary
The cst2 mutant had defective stomatal opening.
- Taxon
- Arabidopsis
Arabidopsise0 - Material
- closed stomata2 (cst2)e0
- Outcome
- defective in stomatal openinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we isolated an Arabidopsis mutant (closed stomata2 (cst2)) that is defective in stomatal opening”
Claim · model-written summary
A mutation in a transporter-like gene caused the mutant phenotype.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- a gene encoding an unknown proteine0
- Outcome
- mutant phenotypee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The mutant phenotype was caused by a mutation in a gene encoding an unknown protein with similarities to the human magnesium (Mg2+) efflux transporter ACDP/CNNM.”
t0“Arabidopsis”
Claim · model-written summary
MGR1/CST2 localized to the tonoplast.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- MGR1/CST2e0
- Outcome
- localized to the tonoplaste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MGR1/CST2 was localized to the tonoplast and showed transport activity for Mg2+”
t0“Arabidopsis”
Claim · model-written summary
MGR1/CST2 transported Mg2+.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- MGR1/CST2e0
- Outcome
- transport activity for Mg2+e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MGR1/CST2 was localized to the tonoplast and showed transport activity for Mg2+”
t0“Arabidopsis”
Claim · model-written summary
MGR1/CST2 was highly and constitutively expressed in guard cells.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- guard cellse0
- Gene
- This proteine0
- Outcome
- constitutively and highly expressede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This protein was constitutively and highly expressed in guard cells”
t0“Arabidopsis”
Claim · model-written summary
MGR1/CST2 knockout closed stomata and reduced photosynthesis and growth, especially at high Mg2+.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Knockout of this genee0
- Outcome
- stomatal closing, decreased photosynthesis and growth retardatione0
- Direction
- decreasede0
- Qualifier
- especially under high Mg2+ conditionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Knockout of this gene resulted in stomatal closing, decreased photosynthesis and growth retardation, especially under high Mg2+ conditions”
t0“Arabidopsis”
Claim · model-written summary
MGR1/CST2 overexpression increased stomatal opening and high-Mg2+ tolerance.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- overexpression of this genee0
- Outcome
- stomatal opening and tolerance to high Mg2+ concentrationse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“overexpression of this gene increased stomatal opening and tolerance to high Mg2+ concentrations”
t0“Arabidopsis”
Claim · model-written summary
Guard-cell expression partly restored mutant stomatal opening.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- guard cell-specific expression of MGR1/CST2e0
- Outcome
- stomatal openinge0
- Direction
- partially restorede0
- Comparator
- the mutante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“guard cell-specific expression of MGR1/CST2 in the mutant partially restored its stomatal opening”
t0“Arabidopsis”
Claim · model-written summary
The authors infer that guard-cell MGR1/CST2 maintains cytosolic Mg2+ by vacuolar sequestration, enabling opening.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- leaf guard cellse0
- Gene
- MGR1/CST2e0
- Outcome
- stomatal openinge0
- Qualifier
- sequestering Mg2+ into vacuolese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MGR1/CST2 expression in the leaf guard cells plays an important role in maintaining cytosolic Mg2+ concentrations through sequestering Mg2+ into vacuoles, which is required for stomatal opening, especially under high Mg2+ conditions”
t0“Arabidopsis”