Abstract
Arabidopsis (Arabidopsis thaliana) mutants lacking the tonoplastic malate transporter AttDT (A. thaliana tonoplast dicarboxylate transporter) and wild-type plants showed no phenotypic differences when grown under standard conditions. To identify putative metabolic changes in AttDT knock-out plants, we provoked a metabolic scenario connected to an increased consumption of dicarboxylates. Acidification of leaf discs stimulated dicarboxylate consumption and led to extremely low levels of dicarboxylates in mutants. To investigate whether reduced dicarboxylate concentrations in mutant leaf cells and, hence, reduced capacity to produce OH(-) to overcome acidification might affect metabolism, we measured photosynthetic oxygen evolution under conditions where the cytosol is acidified. AttDT::tDNA protoplasts showed a much stronger inhibition of oxygen evolution at low pH values when compared to wild-type protoplasts. Apparently citrate, which is present in higher amounts in knock-out plants, is not able to replace dicarboxylates to overcome acidification. To raise more information on the cellular level, we performed localization studies of carboxylates. Although the total pool of carboxylates in mutant vacuoles was nearly unaltered, these organelles contained a lower proportion of malate and fumarate and a higher proportion of citrate when compared to wild-type vacuoles. These alterations concur with the observation that radioactively labeled malate and citrate are transported into Arabidopsis vacuoles by different carriers. In addition, wild-type vacuoles and corresponding organelles from AttDT::tDNA mutants exhibited similar malate channel activities. In conclusion, these results show that Arabidopsis vacuoles contain at least two transporters and a channel for dicarboxylates and citrate and that the activity of AttDT is critical for regulation of pH homeostasis.
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Claims 13
Claim · model-written summary
AttDT mutants and wild type showed no phenotypic difference under standard conditions.
- Taxon
- Arabidopsis (Arabidopsis thaliana)
Arabidopsis thalianae0 - Material
- mutants lacking the tonoplastic malate transporter AttDTe0
- Outcome
- phenotypic differencese0
- Direction
- no phenotypic differencese0
- Comparator
- wild-type plantse0
- Setting
- standard conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) mutants lacking the tonoplastic malate transporter AttDT (A. thaliana tonoplast dicarboxylate transporter) and wild-type plants showed no phenotypic differences when grown under standard conditions.”
Claim · model-written summary
Acidification stimulated dicarboxylate consumption in leaf discs.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- leaf discse0
- Treatment
- Acidification of leaf discse0
- Outcome
- dicarboxylate consumptione0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Acidification of leaf discs stimulated dicarboxylate consumption and led to extremely low levels of dicarboxylates in mutants.”
t0“Arabidopsis”
Claim · model-written summary
Acidification left mutant leaf discs with extremely low dicarboxylate levels.
- Taxon
- ArabidopsisArabidopsist0
- Material
- mutantse0
- Organ / stage
- leaf discse0
- Treatment
- Acidification of leaf discse0
- Outcome
- levels of dicarboxylatese0
- Direction
- extremely lowe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Acidification of leaf discs stimulated dicarboxylate consumption and led to extremely low levels of dicarboxylates in mutants.”
t0“Arabidopsis”
Claim · model-written summary
Low pH inhibited oxygen evolution more strongly in AttDT mutant than wild-type protoplasts.
- Taxon
- ArabidopsisArabidopsist0
- Material
- AttDT::tDNAe0
- Organ / stage
- protoplastse0
- Treatment
- low pH valuese0
- Outcome
- oxygen evolutione0
- Direction
- much stronger inhibitione0
- Comparator
- wild-type protoplastse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AttDT::tDNA protoplasts showed a much stronger inhibition of oxygen evolution at low pH values when compared to wild-type protoplasts.”
t0“Arabidopsis”
Claim · model-written summary
Knock-out plants had higher citrate amounts.
- Taxon
- ArabidopsisArabidopsist0
- Material
- knock-out plantse0
- Outcome
- citratee0
- Direction
- higher amountse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Apparently citrate, which is present in higher amounts in knock-out plants, is not able to replace dicarboxylates to overcome acidification.”
t0“Arabidopsis”
Claim · model-written summary
The authors infer that citrate cannot replace dicarboxylates in countering acidification.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- citratee0
- Outcome
- overcome acidificatione0
- Qualifier
- not able to replace dicarboxylatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Apparently citrate, which is present in higher amounts in knock-out plants, is not able to replace dicarboxylates to overcome acidification.”
t0“Arabidopsis”
Claim · model-written summary
Total vacuolar carboxylate pool was nearly unchanged in mutant plants.
- Taxon
- ArabidopsisArabidopsist0
- Material
- mutante0
- Organ / stage
- vacuolese0
- Outcome
- total pool of carboxylatese0
- Direction
- nearly unalterede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Although the total pool of carboxylates in mutant vacuoles was nearly unaltered, these organelles contained a lower proportion of malate and fumarate and a higher proportion of citrate when compared to wild-type vacuoles.”
t0“Arabidopsis”
Claim · model-written summary
Mutant vacuoles contained lower malate and fumarate proportions than wild-type vacuoles.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- vacuolese0
- Outcome
- proportion of malate and fumaratee0
- Direction
- lowere0
- Comparator
- wild-type vacuolese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these organelles contained a lower proportion of malate and fumarate and a higher proportion of citrate when compared to wild-type vacuoles.”
t0“Arabidopsis”
Claim · model-written summary
Mutant vacuoles contained a higher citrate proportion than wild-type vacuoles.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- vacuolese0
- Outcome
- proportion of citratee0
- Direction
- highere0
- Comparator
- wild-type vacuolese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these organelles contained a lower proportion of malate and fumarate and a higher proportion of citrate when compared to wild-type vacuoles.”
t0“Arabidopsis”
Claim · model-written summary
Labeled malate and citrate entered Arabidopsis vacuoles through different carriers.
- Taxon
- ArabidopsisArabidopsise0
- Organ / stage
- vacuolese0
- Outcome
- malate and citrate are transportede0
- Qualifier
- different carrierse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“radioactively labeled malate and citrate are transported into Arabidopsis vacuoles by different carriers.”
Claim · model-written summary
Wild-type and AttDT mutant vacuoles had similar malate channel activities.
- Taxon
- ArabidopsisArabidopsist0
- Material
- AttDT::tDNA mutantse0
- Organ / stage
- vacuolese0
- Outcome
- malate channel activitiese0
- Direction
- similare0
- Comparator
- wild-type vacuolese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wild-type vacuoles and corresponding organelles from AttDT::tDNA mutants exhibited similar malate channel activities.”
t0“Arabidopsis”
Claim · model-written summary
Authors conclude Arabidopsis vacuoles have at least two transporters and a channel for dicarboxylates and citrate.
- Taxon
- ArabidopsisArabidopsise0
- Organ / stage
- vacuolese0
- Gene
- AttDTe0
- Outcome
- at least two transporters and a channel for dicarboxylates and citratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis vacuoles contain at least two transporters and a channel for dicarboxylates and citrate and that the activity of AttDT is critical for regulation of pH homeostasis.”
Claim · model-written summary
Authors conclude AttDT activity is critical for pH homeostasis.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AttDTe0
- Outcome
- regulation of pH homeostasise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the activity of AttDT is critical for regulation of pH homeostasis.”
t0“Arabidopsis”
The same questions in other papers
ph · pest · ArabidopsisResults agree
1 paper in the same direction as this paper
- negative
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.