Abstract
Summary Intracellular malate–starch interconversion plays an important role in stomatal movements. We investigated whether malate or oxaloacetate from the cytosolic membrane side regulate anion channels in the plasma membrane of Arabidopsis thaliana guard cells. Physiological concentrations of cytosolic malate have been reported in the range of 0.4–3 mM in leaf cells. Guard cell patch clamp and two‐electrode oocyte voltage‐clamp experiments were pursued. We show that a concentration of 1 mM cytosolic malate greatly activates S‐type anion channels in Arabidopsis thaliana guard cells. Interestingly, 1 mM cytosolic oxaloacetate also activates S‐type anion channels. Malate activation was abrogated at 10 mM malate and in SLAC 1 anion channel mutant alleles. Interestingly, malate activation of S‐type anion currents was disrupted at below resting cytosolic‐free calcium concentrations ([Ca 2+ ] cyt ), suggesting a key role for basal [Ca 2+ ] cyt signaling. Cytosolic malate was not able to directly activate or enhance SLAC 1‐mediated anion currents in Xenopus oocytes, whereas in positive controls, cytosolic Na HCO 3 enhanced SLAC 1 activity, suggesting that malate may not directly modulate SLAC 1. Cytosolic malate activation of S‐type anion currents was impaired in ost1 and in cpk5/6/11/23 quadruple mutant guard cells. Together these findings show that these cytosolic organic anions function in guard cell ‘plasma membrane’ ion channel regulation.
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Claims 9
Claim · model-written summary
One mM cytosolic malate activated guard cell S-type anion channels.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae0 - Organ / stage
- guard cellse0
- Treatment
- 1 mM cytosolic malatee0
- Outcome
- S‐type anion channelse0
- Direction
- activatese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a concentration of 1 mM cytosolic malate greatly activates S‐type anion channels in Arabidopsis thaliana guard cells”
Claim · model-written summary
One mM cytosolic oxaloacetate activated S-type anion channels.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Organ / stage
- guard cellse1
- Treatment
- 1 mM cytosolic oxaloacetatee0
- Outcome
- S‐type anion channelse0
- Direction
- activatese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“1 mM cytosolic oxaloacetate also activates S‐type anion channels”
e1“plasma membrane of Arabidopsis thaliana guard cells”
Claim · model-written summary
Malate activation was abolished at 10 mM malate.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- 10 mM malatee0
- Outcome
- Malate activatione0
- Direction
- abrogatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Malate activation was abrogated at 10 mM malate”
e1“plasma membrane of Arabidopsis thaliana guard cells”
Claim · model-written summary
Malate activation was abolished in SLAC1 mutant alleles.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Gene
- SLAC 1e0
- Outcome
- Malate activatione0
- Direction
- abrogatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Malate activation was abrogated at 10 mM malate and in SLAC 1 anion channel mutant alleles.”
e1“plasma membrane of Arabidopsis thaliana guard cells”
Claim · model-written summary
Below-resting cytosolic calcium disrupted malate activation of anion currents.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- below resting cytosolic‐free calcium concentrationse0
- Outcome
- malate activation of S‐type anion currentse0
- Direction
- disruptede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“malate activation of S‐type anion currents was disrupted at below resting cytosolic‐free calcium concentrations ([Ca 2+ ] cyt )”
e1“plasma membrane of Arabidopsis thaliana guard cells”
Claim · model-written summary
Malate did not directly activate or enhance SLAC1-mediated currents in Xenopus oocytes.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- Cytosolic malatee0
- Gene
- SLAC 1e0
- Outcome
- SLAC 1‐mediated anion currentse0
- Direction
- not able to directly activate or enhancee0
- Setting
- Xenopus oocytese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cytosolic malate was not able to directly activate or enhance SLAC 1‐mediated anion currents in Xenopus oocytes”
e1“plasma membrane of Arabidopsis thaliana guard cells”
Claim · model-written summary
Cytosolic sodium bicarbonate enhanced SLAC1 activity in positive controls.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- cytosolic Na HCO 3e0
- Gene
- SLAC 1e0
- Outcome
- SLAC 1 activitye0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cytosolic Na HCO 3 enhanced SLAC 1 activity”
e1“plasma membrane of Arabidopsis thaliana guard cells”
Claim · model-written summary
Malate activation was impaired in ost1 mutant guard cells.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Gene
- ost1e0
- Outcome
- Cytosolic malate activation of S‐type anion currentse0
- Direction
- impairede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cytosolic malate activation of S‐type anion currents was impaired in ost1 and in cpk5/6/11/23 quadruple mutant guard cells.”
e1“plasma membrane of Arabidopsis thaliana guard cells”
Claim · model-written summary
Malate activation was impaired in cpk5/6/11/23 quadruple mutant guard cells.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Gene
- cpk5/6/11/23e0
- Outcome
- Cytosolic malate activation of S‐type anion currentse0
- Direction
- impairede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cytosolic malate activation of S‐type anion currents was impaired in ost1 and in cpk5/6/11/23 quadruple mutant guard cells.”
e1“plasma membrane of Arabidopsis thaliana guard cells”
The same questions in other papers
calcium atom · molecular: metabolites · Arabidopsis thaliana (thale cress)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.