Alleviation of Copper Rhizotoxicity by Calcium and Magnesium at Defined Free Metal‐Ion Activities

Parker, David R.; Pedler, Judith F.; Thomason, David N.; Li, Huiying

doi:10.2136/sssaj1998.03615995006200040017x

Cited by 51 publications

(53 citation statements)

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“…This is perhaps not too surprising, as the exchangeable Ca concentrations in the serpentine soils used in Anderson et al (1973) were low (less than 30% of total CEC), relative to what is common for nonserpentine soils (60Á80% of total CEC), thus potentially posing less competition for Ni uptake by plants ( Kinraide 1998;Parker et al 1998). The data of Weng et al (2003) suggest that the EC 25 for shoot biomass occurred at approximately 4 mmol Ni kg…”

Section: Discussionmentioning

confidence: 98%

Toxicity thresholds for oat (Avena sativa L.) grown in Ni-impacted agricultural soils near Port Colborne, Ontario, Canada

Dan¹,

Hale²,

Johnson³

et al. 2008

Can. J. Soil. Sci.

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This study established Ni phytotoxicity thresholds for oat (Avena sativa L.) in four soil types, each created by blending a low and a high Ni soil, to generate a range of concentrations. The first quartile effective concentration (EC25) for soil and shoot tissue Ni concentration and reduction in shoot dry weight (DW) was determined using a Weibull function. The EC25 (for soil Ni concentration) was 1350, 1950, 1880 and > 2400 mg Ni kg-1 soil, for sand, till clay, heavy clay and organic muck, respectively. The EC25 (for shoot Ni concentration) was 71, 21, 52 and > 35 mg Ni kg-1 shoot DW, for sand, till clay, heavy clay and organic muck, respectively. Total soil Ni concentration, soil pH and soil cation exchange capacity (CEC) accounted for 70% of the variation of Ni accumulation in tissue when the data for all four of the soils were combined; this was similar to the amount of variation accounted for by fitting Ni concentration in tissue to ammonium oxalate extractable soil Ni. Manganese deficiency may have impaired plant growth at higher soil Ni concentrations in the clay soils. Speciation of Ni was similar in all soils studied, and the relationship between Ni concentrations in soil and in tissue was less closely related to chemically extracted soil Ni than it was to a combination of total soil Ni, soil pH and CEC. These are the soil characteristics known to influence both equilibrium among metal species in soil solution, and uptake of cations by plants. Key words: Avena sativa L., EC25, Ni, oat

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Section: Discussionmentioning

confidence: 98%

Toxicity thresholds for oat (Avena sativa L.) grown in Ni-impacted agricultural soils near Port Colborne, Ontario, Canada

Dan¹,

Hale²,

Johnson³

et al. 2008

Can. J. Soil. Sci.

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“…This is consistent with the studies for Ni toxicity by Lock et al (2007b) and also for some other metals (de Schamphelaere and Janssen 2002; Heijerick et al 2002b;Lock et al 2007a). However, more previous studies have observed a significant correlation between EC50 and pH at EC50 (Erickson et al 1996;Heijerick et al 2002a;Parker et al 1998;Thakali et al 2006a, b;Voigt et al 2006). Hence, incorporation of proton competition into the concept of BLM remains to be justified (Wang et al 2009).…”

Section: Variation and Prediction Of Ni Ec50mentioning

confidence: 96%

Leaching impacts Ni toxicity differently among soils but increases its predictability according to nitrification assay

Huang

et al. 2009

J Soils Sediments

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Purpose Deriving toxicity thresholds through bioassays has become the scientific basis for the risk assessment of metal contamination in soils, but few studies have been reported for Ni toxicity in Chinese soils. In addition, although leaching has been recommended to increase the ecological relevance of the output of soil toxicity bioassays, its impacts on Ni threshold and soil solutions in soils remained to be shown. Therefore, in this study, 17 soils were collected throughout China and were assessed for Ni toxicity using substrate-induced nitrification (SIN) assay for both un-leached and leached treatments. Meanwhile, soil solutions of all Ni treatments were extracted and analyzed. This study provides information for the development of a terrestrial biotic ligand model (TBLM) for Ni in Chinese soils.Materials and methods Soils were artificially amended with NiCl 2 solution to generate nominal Ni contamination levels, and aliquot of each Ni treatment was leached with artificial rain to prepare leached soil samples. All the 17 unleached and the 17 leached soils were subjected to the standard SIN protocol. A total of 816 microcosm tubes were established. Soil solution was extracted, and the solution physiochemical properties were analyzed for each Ni treatments. Both the total-Ni-based and the solution-Nibased median effective concentrations (EC50) in unleached soils and leached soils were calculated from dose-response curves. Free-Ni 2+ -based EC50 was also calculated based on solution chemical properties. Leaching effect was assessed based on these results. Results and discussion Ni EC50 varied largely among soils for both the total-Ni-based and the solution-Ni-based EC50 in un-leached soils. In un-leached soils, the total-Ni-based EC50 values ranged from 52.8 mg kg −1 (Hulunber soil) to 2,385.4 mg kg −1 (Wulumuqi soil), and the solution-Nibased EC50 ranged from 0.70 mg L −1 (Jiaxing soil) to 293.35 mg L −1 (Wulumuqi soil). Stepwise multiple regressions showed that soil pH and total Ca were the best predictors for the total-Ni-based EC50. Protective effects of Ca 2+ and Mg 2+ but not H + against Ni toxicity in soil solution were found. Leaching impacted Ni EC50 differently among soils, with leaching factor ranging from 0.2 (Haikou soil) to 19.7 (Hulunber soil) for the total-Ni-based EC50 and from 0.1 (Dezhou soil) to 35.7 (Jiaxing soil) for the solution-Ni-based EC50. In addition, predictability of Ni EC50 was higher in leached soils. The variations in Ni EC50 were in agreement with the findings in previous studies. Soil pH and Ca may play important roles in the partition of Ni in Chinese soils and thus impact the Ni toxicity. Protective effects of Ca 2+ and Mg 2+ in soil solutions against Ni toxicity may exist, but the role of H +

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“…The ability of Cu to mediate high rates of electron transfer is also a potential cause of toxicity for plant cells (especially in growing roots). Less than 5 mM Cu inhibits the growth of roots in wheat (Triticum aestivum; Taylor et al, 1991;Parker et al, 1998) and Arabidopsis (Arabidopsis thaliana; Toda et al, 1999). This sensitivity of growing roots is a potential risk in agriculture that arises from the use of Cu-containing fungicides and fertilizers.…”

mentioning

confidence: 99%

Amino Acid Polymorphisms in Strictly Conserved Domains of a P-Type ATPase HMA5 Are Involved in the Mechanism of Copper Tolerance Variation in Arabidopsis

et al. 2008

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Copper (Cu) is an essential element in plant nutrition, but it inhibits the growth of roots at low concentrations. Accessions of Arabidopsis (Arabidopsis thaliana) vary in their tolerance to Cu. To understand the molecular mechanism of Cu tolerance in Arabidopsis, we performed quantitative trait locus (QTL) analysis and accession studies. One major QTL on chromosome 1 (QTL1) explained 52% of the phenotypic variation in Cu tolerance in roots in a Landsberg erecta/Cape Verde Islands (Ler/Cvi) recombinant inbred population. This QTL regulates Cu translocation capacity and involves a Cu-transporting P1B-1-type ATPase, HMA5. The Cvi allele carries two amino acid substitutions in comparison with the Ler allele and is less functional than the Ler allele in Cu tolerance when judged by complementation assays using a T-DNA insertion mutant. Complementation assays of the ccc2 mutant of yeast using chimeric HMA5 proteins revealed that N923T of the Cvi allele, which was identified in the tightly conserved domain N(x)6YN(x)4P (where the former asparagine was substituted by threonine), is a cause of dysfunction of the Cvi HMA5 allele. Another dysfunctional HMA5 allele was identified in Chisdra-2, which showed Cu sensitivity and low capacity of Cu translocation from roots to shoots. A unique amino acid substitution of Chisdra-2 was identified in another strictly conserved domain, CPC(x)6P, where the latter proline was replaced with leucine. These results indicate that a portion of the variation in Cu tolerance of Arabidopsis is regulated by the functional integrity of the Cu-translocating ATPase, HMA5, and in particular the amino acid sequence in several strictly conserved motifs.

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Alleviation of Copper Rhizotoxicity by Calcium and Magnesium at Defined Free Metal‐Ion Activities

Cited by 51 publications

References 0 publications

Toxicity thresholds for oat (Avena sativa L.) grown in Ni-impacted agricultural soils near Port Colborne, Ontario, Canada

Toxicity thresholds for oat (Avena sativa L.) grown in Ni-impacted agricultural soils near Port Colborne, Ontario, Canada

Leaching impacts Ni toxicity differently among soils but increases its predictability according to nitrification assay

Amino Acid Polymorphisms in Strictly Conserved Domains of a P-Type ATPase HMA5 Are Involved in the Mechanism of Copper Tolerance Variation in Arabidopsis

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