Zinc rhizotoxicity in wheat and radish is alleviated by micromolar levels of magnesium and potassium in solution culture

Pedler, Judith F.; Kinraide, Thomas B.; Parker, David R.

doi:10.1023/b:plso.0000020958.42158.f5

Cited by 47 publications

(46 citation statements)

References 29 publications

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“…Previous studies have also shown that Cu 2+ and Zn 2+ at low doses were highly toxic to plant roots Pedler et al, 2004). Tin was slightly toxic to cv.…”

Section: Protective Effect Of Mg and Other Divalent Cations Against Amentioning

confidence: 85%

“…The low cation concentrations employed do not support the explanation of a protective action based on the increase of the electrical potential of root cell plasma membrane either (Kinraide et al, 1992; Kinraide, 1994bKinraide, , 1998. In wheat, Pedler et al (2004) found that low Mg 2+ doses were able to completely alleviate Zn 2+ rhizotoxicity, while Ca amelioration, even at much higher doses, was much weaker. The nature of this protective role of Mg 2+ is not quite clear at the moment, but the high effectiveness of low Mg 2+ concentrations indicates the involvement of a biochemical/physiological mechanism.…”

Section: Protective Effect Of Mg and Other Divalent Cations Against Amentioning

confidence: 93%

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Protective effect of divalent cations against aluminum toxicity in soybean

Silva

Corrêa

Novais

et al. 2008

Rev. Bras. Ciênc. Solo

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SUMMARYA large proportion of soybean fields in Brazil are currently cultivated in the Cerrado region, where the area planted with this crop is growing considerably every year. Soybean cultivation in acid soils is also increasing worldwide. Since the levels of toxic aluminum (Al) in these acid soils is usually high it is important to understand how cations can reduce Al rhizotoxicity in soybean. In the present study we evaluated the ameliorative effect of nine divalent cations (Ca, Mg, Mn, Sr, Sn, Cu, Zn, Co and Ba) in solution culture on Al rhizotoxicity in soybean. The growth benefit of Ca and Mg to plants in an acid Inceptisol was also evaluated. In this experiment soil exchangeable Ca:Mg ratios were adjusted to reach 10 and 60 % base saturation, controlled by different amounts of CaCl 2 or MgCl 2 (at proportions from 100:0 up to 0:100), without altering the soil pH level. The low (10 %) and adequate (60 %) base saturation were used to examine how plant roots respond to Al at distinct (Ca + Mg)/Al ratios, as if they were growing in soils with distinct acidity levels. Negative and positive control treatments consisted of absence (under native soil or undisturbed conditions) or presence of lime (CaCO 3 ) to reach 10 and 60 % base saturation, respectively. It was observed that in the absence of Aluminum, Cu, Zn, Co and Sn were toxic even at a low concentration (25 μmol L -1 ), while the effect of Mn, Ba, Sr and Mg was positive or absent on soybean root elongation when used in concentrations up to 100 μmol L -1 . At a level of 10 μmol L -1 Al, root growth was only reverted to the level of control plants by the Mg treatment. Higher Tin doses led to a small alleviation of Al rhizotoxicity, while the other cations reduced root growth or had no effect. This is an indication that the Mg effect is ion-specific and not associated to an electrostatic protection mechanism only, since all ions were divalent and used at low concentrations. An increased exchangeable Ca:Mg Uma grande parte da soja no Brazil é cultivada atualmente na região do Cerrado, e é nessa região que ocorre a maior expansão da cultura. Nessa região, a maioria dos solos é ácida e, geralmente, apresenta níveis elevados de alumínio (Al) tóxico. Portanto, é importante compreender como determinados cátions reduzem a rizotoxidez de Al em plantas de soja. Neste estudo foram avaliados, em solução nutritiva, o efeito protetor de nove cátions divalentes (Ca, Mg, Mn, Sr, Sn, Cu, Zn, Co and Ba) contra a rizotoxidez de Al e o efeito positivo do Ca e Mg no crescimento das plantas de soja num solo com elevada saturação por Al. A relação entre Ca e Mg trocáveis foi variada por meio de adição de diferentes quantidades de CaCl 2 ou MgCl 2 (com as proporções variando entre 100:0 até 0:100), sem que ocorresse alteração no pH do solo. Tratamentos testemunhas consistiram de solo sem aplicação ou com aplicação de calcário (CaCO 3 ). Foi observado que, na ausência do Al, os cátions Cu, Zn, Co e Sn foram tóxicos mesmo em baixas concentrações (25 μmol L -1 ), enquanto Mn, Ba, Sr e...

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“…Previous studies have also shown that Cu 2+ and Zn 2+ at low doses were highly toxic to plant roots Pedler et al, 2004). Tin was slightly toxic to cv.…”

Section: Protective Effect Of Mg and Other Divalent Cations Against Amentioning

confidence: 85%

Section: Protective Effect Of Mg and Other Divalent Cations Against Amentioning

confidence: 93%

Protective effect of divalent cations against aluminum toxicity in soybean

Silva

Corrêa

Novais

et al. 2008

Rev. Bras. Ciênc. Solo

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“…Interestingly, preliminary results showed also an interplay between zinc and magnesium in O. maius strain Zn (data not shown). The increase of magnesium content in yeast may reflect competition/inhibition with zinc uptake, and could protect cells by interfering with the mechanisms of zinc toxicity, as observed in plants ( Pedler et al, 2004). Further experiments, for example with yeast mutants for iron and magnesium uptake, and with O. maius mutants, will help to elucidate this suggested role.…”

Section: Discussionmentioning

confidence: 96%

“…The effect of intracellular and extracellular magnesium concentrations on heavy metal toxicity has been described in several studies, although the mechanisms have not been elucidated. A general protective effect of magnesium against heavy-metal cations such as manganese, copper, nickel, cadmium and cobalt in yeast ( Blackwell et al, 1998, Karamushka and Gadd, 1994, Joho et al, 1991, Kessels et al, 1985and Norris and Kelly, 1979, and zinc and cadmium in plants ( Pedler et al, 2004 andKupper andKochian, 2010) has been reported. In particular, the uptake of divalent cations in yeast was reduced by the addition of extracellular magnesium ( Pisat et al, 2009, Blackwell et al, 1998and Bianchi et al, 1981.…”

Section: Discussionmentioning

confidence: 98%

OmZnT1 and OmFET, two metal transporters from the metal-tolerant strain Zn of the ericoid mycorrhizal fungus Oidiodendron maius, confer zinc tolerance in yeast

Khouja

Abbà

Lacercat-Didier

et al. 2013

Fungal Genetics and Biology

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Two full-length cDNAs (OmZnT1 and OmFET) encoding membrane transporters were identified by yeast functional screening in the heavy metal tolerant ericoid mycorrhizal isolate Oidiodendron maius Zn. OmZnT1 belongs to the Zn-Type subfamily of the cation diffusion facilitators, whereas OmFET belongs to the family of iron permeases. Their properties were investigated in yeast by functional complementation of mutants affected in metal uptake and metal tolerance. Heterologous expression of OmZnT1 and OmFETin a Zn-sensitive yeast mutant restored the wild-type phenotype. Additionally, OmZnT1expression also restored cobalt tolerance in a Co-sensitive mutant. A GFP fusion protein revealed that OmZnT1 was targeted to the endoplasmic reticulum membrane, a result consistent with a function for OmZnT1 in metal sequestration. Similarly to other iron permeases, OmFET-GFP was localized on the plasma membrane. OmFET restored the growth of uptake-defective strains for iron and zinc. Zinc-sensitive yeast mutants expressing OmFET specifically accumulated magnesium, as compared to cells transformed with the empty vector. We suggest that OmFET may counteract zinc toxicity by increasing entry of magnesium into the cell.

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“…Root responses, including elongation, toxicity, alleviation of toxicity, ion uptake, and PM enzyme activity, to a particular ion, I, often correlate poorly with the activity of the ion in the bulk medium ({I z } b ) but are often more closely related to the ion's activity at the outer surface of the PM ({I z } 0 o ) [7,[14][15][16]. Many studies have reported that Mg is more effective than Ca in alleviating the rhizotoxic effects of Al [6,17] [8], Ni [18], and Zn [6,9], but the mechanisms whereby this occurs were not explored. Recently, we noted a similar effect on the toxicity of Ni and Co (our unpublished data), but little evidence exists that this occurs with anionic toxicants.…”

Section: Introductionmentioning

confidence: 99%

Calcium and magnesium enhance arsenate rhizotoxicity and uptake in Triticum aestivum

Wang

Zhou

Weng

et al. 2011

Enviro Toxic and Chemistry

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Cations such as calcium (Ca) and magnesium (Mg) alleviate toxicities of cationic toxicants and increase those of anionic toxicants such as arsenic (As) present as arsenate under aerobic conditions. Increasing evidence exists that these phenomena are related to the outer surface electrical potential (ψ 0°) of the root cell plasma membrane (PM). Short-term (48-h) nutrient culture experiments with wheat (Triticum aestivum L.) seedlings investigated Ca and Mg effects on arsenate rhizotoxicity and uptake. Increased Ca and Mg in solution from 0.2 to 3.5 mM equally reduced the negativity of ψ 0° from -45 to -15 mV. This increased arsenate activity at the PM surface from 0.3 to 0.9 µM at the same bulk concentration of 2.0 µM NaH(2) AsO(4) consequently increased arsenate uptake and rhizotoxicity. However, increased Mg was more effective than Ca in enhancing As uptake by roots, especially with the activity of As in the range of 0.5 to 1.5 µM in the bulk medium. This was explained by a modified electrostatic uptake model which indicated a mechanism other than through an effect on ψ 0°. Subcellular fractionation of roots indicated that > 95% of As was associated with cellular debris and heat-stable protein (HSP). The results of the present study show that Ca and Mg reduce the negativity of ψ 0°, increasing arsenate uptake and rhizotoxicity, and suggest that Mg is more efficient than Ca in enhancing the uptake of As due, in large part, to inducing greater As binding by peptides in the HSP fraction.

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Zinc rhizotoxicity in wheat and radish is alleviated by micromolar levels of magnesium and potassium in solution culture

Cited by 47 publications

References 29 publications

Protective effect of divalent cations against aluminum toxicity in soybean

Protective effect of divalent cations against aluminum toxicity in soybean

OmZnT1 and OmFET, two metal transporters from the metal-tolerant strain Zn of the ericoid mycorrhizal fungus Oidiodendron maius, confer zinc tolerance in yeast

Calcium and magnesium enhance arsenate rhizotoxicity and uptake in Triticum aestivum

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