Abstract
The effects of salinity (NaCl) stress on growth, cytosolic Ca(2+) gradients and cytosolic pH homeostasis of root hairs of Arabidopsis thaliana are assessed here. Neither cytosolic Ca(2+) nor pH at the hair apex were significantly affected by 20 min exposure of up to 90 mM NaCl or of up to 5 mM extracellular Ca(2+). Exposure to increasing NaCl concentrations, up to 90 mM, for 2 d or 6 d reduced hair extension, and this inhibition was relieved by supplemental extracellular Ca(2+). Such extended salinity stress reduced the magnitude of the Ca(2+) gradient in the apical 12 microm of hairs at all NaCl concentrations tested (up to 90 mM), including NaCl concentrations that did not reduce hair extension. The magnitude of the tip-focused gradient was also reduced in root hairs of plants grown with low (0.5 mM) extracellular Ca(2+) when compared to those in 5 mM extracellular Ca(2+), regardless of the presence of NaCl. Up to 90 mM NaCl did not affect cytosolic pH of root hairs in any of the treatments. It is concluded that NaCl inhibition of root hair extension in the long term may operate via alterations in the tip-focused Ca(2+) gradient that regulates root hair growth. However, NaCl-induced alterations in this gradient do not always lead to detectably altered growth kinetics. Short-term signalling events in response to NaCl may operate by a means other than altering Ca(2+) at the root hair apex. Salinity stress in root hairs does not appear to be mediated by effects on cytosolic pH.
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Claims 13
Claim · model-written summary
Short exposure to up to 90 mM NaCl did not significantly alter calcium at the root-hair apex.
- Taxon
- Arabidopsis thaliana L.
Arabidopsis thalianat0 - Organ / stage
- hair apexe0
- Treatment
- up to 90 mM NaCle0
- Outcome
- cytosolic Ca(2+)e0
- Direction
- Neithere0
- Qualifier
- 20 mine0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither cytosolic Ca(2+) nor pH at the hair apex were significantly affected by 20 min exposure of up to 90 mM NaCl or of up to 5 mM extracellular Ca(2+)”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
Short exposure to up to 90 mM NaCl did not significantly alter pH at the root-hair apex.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Organ / stage
- hair apexe0
- Treatment
- up to 90 mM NaCle0
- Outcome
- pHe0
- Direction
- Neithere0
- Qualifier
- 20 mine0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither cytosolic Ca(2+) nor pH at the hair apex were significantly affected by 20 min exposure of up to 90 mM NaCl or of up to 5 mM extracellular Ca(2+)”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
Short exposure to up to 5 mM extracellular calcium did not significantly alter apical cytosolic calcium.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Organ / stage
- hair apexe0
- Treatment
- up to 5 mM extracellular Ca(2+)e0
- Outcome
- cytosolic Ca(2+)e0
- Direction
- Neithere0
- Qualifier
- 20 mine0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither cytosolic Ca(2+) nor pH at the hair apex were significantly affected by 20 min exposure of up to 90 mM NaCl or of up to 5 mM extracellular Ca(2+)”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
Short exposure to up to 5 mM extracellular calcium did not significantly alter apical pH.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Organ / stage
- hair apexe0
- Treatment
- up to 5 mM extracellular Ca(2+)e0
- Outcome
- pHe0
- Direction
- Neithere0
- Qualifier
- 20 mine0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither cytosolic Ca(2+) nor pH at the hair apex were significantly affected by 20 min exposure of up to 90 mM NaCl or of up to 5 mM extracellular Ca(2+)”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
Two or six days of increasing NaCl up to 90 mM reduced root-hair extension.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Treatment
- increasing NaCl concentrations, up to 90 mMe0
- Outcome
- hair extensione0
- Direction
- reducede0
- Qualifier
- 2 d or 6 de0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exposure to increasing NaCl concentrations, up to 90 mM, for 2 d or 6 d reduced hair extension”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
Supplemental extracellular calcium relieved NaCl inhibition of root-hair extension.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Treatment
- supplemental extracellular Ca(2+)e0
- Outcome
- hair extensione1
- Direction
- relievede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this inhibition was relieved by supplemental extracellular Ca(2+)”
e1“Exposure to increasing NaCl concentrations, up to 90 mM, for 2 d or 6 d reduced hair extension”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
Extended salinity stress reduced the apical calcium gradient, including at NaCl levels that did not reduce extension.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Organ / stage
- apical 12 microm of hairse0
- Treatment
- extended salinity stresse0
- Outcome
- magnitude of the Ca(2+) gradiente0
- Direction
- reducede0
- Qualifier
- including NaCl concentrations that did not reduce hair extensione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Such extended salinity stress reduced the magnitude of the Ca(2+) gradient in the apical 12 microm of hairs at all NaCl concentrations tested (up to 90 mM), including NaCl concentrations that did not reduce hair extension”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
Root hairs grown at 0.5 mM extracellular calcium had a smaller tip-focused calcium gradient than at 5 mM, regardless of NaCl.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Treatment
- low (0.5 mM) extracellular Ca(2+)e0
- Outcome
- magnitude of the tip-focused gradiente0
- Direction
- reducede0
- Qualifier
- regardless of the presence of NaCle0
- Comparator
- 5 mM extracellular Ca(2+)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The magnitude of the tip-focused gradient was also reduced in root hairs of plants grown with low (0.5 mM) extracellular Ca(2+) when compared to those in 5 mM extracellular Ca(2+), regardless of the presence of NaCl”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
NaCl up to 90 mM did not affect root-hair cytosolic pH in any treatment.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Treatment
- Up to 90 mM NaCle0
- Outcome
- cytosolic pH of root hairse0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Up to 90 mM NaCl did not affect cytosolic pH of root hairs in any of the treatments”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
The authors propose that long-term NaCl inhibition of extension may operate through changes in the tip-focused calcium gradient.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Treatment
- NaCle0
- Outcome
- root hair extensione0
- Qualifier
- alterations in the tip-focused Ca(2+) gradiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NaCl inhibition of root hair extension in the long term may operate via alterations in the tip-focused Ca(2+) gradient that regulates root hair growth”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
NaCl-related calcium gradient changes did not always produce detectably changed growth kinetics.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Outcome
- growth kineticse0
- Direction
- do not always lead to detectably alterede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NaCl-induced alterations in this gradient do not always lead to detectably altered growth kinetics”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
The authors propose that short-term NaCl signaling may use a pathway other than changing calcium at the root-hair apex.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Treatment
- NaCle0
- Outcome
- Short-term signalling eventse0
- Qualifier
- other than altering Ca(2+) at the root hair apexe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Short-term signalling events in response to NaCl may operate by a means other than altering Ca(2+) at the root hair apex”
t0“Arabidopsis thaliana L.”
Claim · model-written summary
The authors infer that root-hair salinity stress is not mediated through cytosolic pH changes.
- Taxon
- Arabidopsis thaliana L.Arabidopsis thalianat0
- Outcome
- Salinity stress in root hairse0
- Qualifier
- effects on cytosolic pHe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Salinity stress in root hairs does not appear to be mediated by effects on cytosolic pH”
t0“Arabidopsis thaliana L.”
The same questions in other papers
sodium chloride · growth · Arabidopsis thaliana (thale cress)Results differ
13 papers in the same direction as this paper · 2 in the opposite direction
- positive
- positive
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See all 16 papers →sodium chloride · nutrient: content · Arabidopsis thaliana (thale cress)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- positive
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calcium(2+) · nutrient: content · Arabidopsis thaliana (thale cress)Results agree
1 paper in the same direction as this paper
- no effect
salinity · nutrient: content · Arabidopsis thaliana (thale cress)Results agree
2 papers in the same direction as this paper
- negative
- 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.