Abstract
Across a diverse spectrum of organisms, the absorption and toxicity of trace elements are usually correlated with the activity of the free metal ion, but reported exceptions to this generalization are increasing. For the first time, we tested the validity of the free-ion activity model (FIAM) in the case of terrestrial plants and organic acids that may be abundant in the soil solution and rhizosphere. Short-term (48-h) root elongation of wheat (Triticum aestitvum L.) in a simple medium (2 mM CaCl2, pH 6.0) was used to probe the toxicity of Cu and Zn in the presence of malonate, malate, and citrate. Precautions were taken to prevent biodegradation of the organic acids, and its absence was confirmed by ion chromatography. Copper speciation was verified using a Cu-selective ion electrode, and published stability constants were modified to improve agreement between measured and calculated Cu2+ activities. With additions of both malonate and malate, Cu toxicity was alleviated but not to the extent predicted by the FIAM; the Cu-ligand complexes seemingly contributed to the toxicity. No such departures were observed with citrate and Cu nor with any of the three ligands in combination with Zn. Thus, exceptions to the FIAM occur with higher plants as well as with aquatic biota but do not seem to occur in a predictable or systematic fashion with respect to metal or organic acid under investigation. Several possible explanations for the observed departures from the FIAM are discussed, including the possibility of accidental cotransport of metal and ligand into the cytoplasm.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 5
Claim · model-written summary
Malonate and malate alleviated Cu toxicity to wheat root elongation, but less than the free-ion activity model predicted.
- Taxon
- wheat
Triticum aestivume1 - Treatment
- malonate and malatee2
- Outcome
- Cu toxicitye2
- Direction
- alleviatede2
- Qualifier
- not to the extente2
- Comparator
- predicted by the FIAMe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Short-term (48-h) root elongation of wheat (Triticum aestitvum L.) in a simple medium (2 mM CaCl2, pH 6.0) was used to probe the toxicity of Cu and Zn in the presence of malonate, malate, and citrate”
e2“With additions of both malonate and malate, Cu toxicity was alleviated but not to the extent predicted by the FIAM; the Cu-ligand complexes seemingly contributed to the toxicity”
Claim · model-written summary
Cu-ligand complexes seemingly contributed to Cu toxicity in wheat.
- Taxon
- wheatTriticum aestivume1
- Compound
- Cu-ligand complexese2
- Outcome
- Cu toxicitye2
- Qualifier
- seemingly contributed to the toxicitye2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Short-term (48-h) root elongation of wheat (Triticum aestitvum L.) in a simple medium (2 mM CaCl2, pH 6.0) was used to probe the toxicity of Cu and Zn in the presence of malonate, malate, and citrate”
e2“With additions of both malonate and malate, Cu toxicity was alleviated but not to the extent predicted by the FIAM; the Cu-ligand complexes seemingly contributed to the toxicity”
Claim · model-written summary
No departures from the free-ion activity model were observed for wheat with citrate and Cu.
- Taxon
- wheatTriticum aestivume1
- Outcome
- departurese3
- Qualifier
- with citrate and Cue3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Short-term (48-h) root elongation of wheat (Triticum aestitvum L.) in a simple medium (2 mM CaCl2, pH 6.0) was used to probe the toxicity of Cu and Zn in the presence of malonate, malate, and citrate”
e3“No such departures were observed with citrate and Cu nor with any of the three ligands in combination with Zn”
Claim · model-written summary
No departures from the free-ion activity model were observed for wheat with any of the three ligands in combination with Zn.
- Taxon
- wheatTriticum aestivume1
- Outcome
- departurese3
- Qualifier
- any of the three ligands in combination with Zne3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Short-term (48-h) root elongation of wheat (Triticum aestitvum L.) in a simple medium (2 mM CaCl2, pH 6.0) was used to probe the toxicity of Cu and Zn in the presence of malonate, malate, and citrate”
e3“No such departures were observed with citrate and Cu nor with any of the three ligands in combination with Zn”
Claim · model-written summary
Exceptions to the free-ion activity model occur with higher plants, but not in a predictable or systematic fashion.
- Taxon
- higher plantsEmbryophytae4
- Outcome
- exceptions to the FIAMe4
- Qualifier
- do not seem to occur in a predictable or systematic fashione4
Verbatim
e4“Thus, exceptions to the FIAM occur with higher plants as well as with aquatic biota but do not seem to occur in a predictable or systematic fashion with respect to metal or organic acid under investigation”
The same questions in other papers
malonate ester · pest · Triticum aestivum (wheat)Results agree
1 paper in the same direction as this paper
- positive
malate · pest · Triticum aestivum (wheat)Results agree
2 papers in the same direction as this paper
- positive
- positive
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.