Abstract
One explanation for Al toxicity in plants suggests that Al displaces Ca2+ from critical sites in the apoplasm. We evaluated the Ca2+-displacement hypothesis directly using near-isogenic lines of wheat (Triticum aestivum L.) that differ in Al tolerance at a single locus. We measured both the growth and total accumulation (apoplasmic plus symplasmic) of 45Ca and Al into roots that had been exposed to Al alone or to Al with other cations. Root growth in the Al-sensitive line was found to be severely inhibited by low activities of Al, even though Ca2+ accumulation was relatively unaffected. In solutions containing the same activity of the Al3+ and Ca2+ ions as above, but also including either 3.0 mM Mg2+, 3.0 mM Sr2+, or 30 mM Na+, growth improved, whereas 45Ca2+ accumulation was significantly decreased. Since most of the 45Ca2+ accumulated by roots during short-term treatments will reside in the apoplasm, these results indicate that displacement of Ca2+ from the apoplasm by Al cannot account for the Al-induced inhibition of root growth and, therefore, do not support the Ca2+-displacement hypothesis for Al toxicity. We also show that total accumulation of Al by root apices is greater in the Al-sensitive genotype than the Al-tolerant genotype and suggest that cation amelioration of Al toxicity is caused by the reduction in Al accumulation.
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Claims 7
Claim · model-written summary
Low aluminum activity severely inhibited root growth in the Al-sensitive wheat line.
- Taxon
- wheat
Triticum aestivume1 - Material
- Al-sensitive linee0
- Treatment
- low activities of Ale0
- Outcome
- Root growthe0
- Direction
- severely inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root growth in the Al-sensitive line was found to be severely inhibited by low activities of Al”
e1“wheat (Triticum aestivum L.)”
Claim · model-written summary
Calcium accumulation was relatively unaffected at aluminum levels that inhibited root growth.
- Taxon
- wheatTriticum aestivume1
- Material
- Al-sensitive linee0
- Treatment
- low activities of Ale0
- Outcome
- Ca2+ accumulatione0
- Direction
- relatively unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root growth in the Al-sensitive line was found to be severely inhibited by low activities of Al, even though Ca2+ accumulation was relatively unaffected”
e1“wheat (Triticum aestivum L.)”
Claim · model-written summary
Adding Mg2+, Sr2+, or Na+ improved wheat root growth in aluminum and calcium solutions.
- Taxon
- wheatTriticum aestivume1
- Treatment
- 3.0 mM Mg2+, 3.0 mM Sr2+, or 30 mM Na+e0
- Outcome
- growthe0
- Direction
- improvede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“including either 3.0 mM Mg2+, 3.0 mM Sr2+, or 30 mM Na+, growth improved”
e1“wheat (Triticum aestivum L.)”
Claim · model-written summary
Adding Mg2+, Sr2+, or Na+ significantly decreased wheat root 45Ca2+ accumulation.
- Taxon
- wheatTriticum aestivume1
- Treatment
- 3.0 mM Mg2+, 3.0 mM Sr2+, or 30 mM Na+e0
- Outcome
- 45Ca2+ accumulatione0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“including either 3.0 mM Mg2+, 3.0 mM Sr2+, or 30 mM Na+, growth improved, whereas 45Ca2+ accumulation was significantly decreased”
e1“wheat (Triticum aestivum L.)”
Claim · model-written summary
Al-sensitive wheat root apices accumulated more aluminum than Al-tolerant root apices.
- Taxon
- wheatTriticum aestivume1
- Material
- Al-sensitive genotypee0
- Organ / stage
- root apicese0
- Outcome
- total accumulation of Ale0
- Direction
- greatere0
- Comparator
- Al-tolerant genotypee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total accumulation of Al by root apices is greater in the Al-sensitive genotype than the Al-tolerant genotype”
e1“wheat (Triticum aestivum L.)”
Claim · model-written summary
The authors conclude that calcium displacement cannot explain aluminum-inhibited wheat root growth.
- Taxon
- wheatTriticum aestivume1
- Outcome
- Al-induced inhibition of root growthe0
- Qualifier
- displacement of Ca2+ from the apoplasm by Ale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“displacement of Ca2+ from the apoplasm by Al cannot account for the Al-induced inhibition of root growth”
e1“wheat (Triticum aestivum L.)”
Claim · model-written summary
The authors suggest that cations ameliorate aluminum toxicity by reducing aluminum accumulation.
- Taxon
- wheatTriticum aestivume1
- Outcome
- amelioration of Al toxicitye0
- Qualifier
- reduction in Al accumulatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cation amelioration of Al toxicity is caused by the reduction in Al accumulation”
e1“wheat (Triticum aestivum L.)”
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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.