Significance of root exudates in acquisition of heavy metals from a contaminated calcareous soil by graminaceous species

Römheld, Volker; Awad, F.

doi:10.1080/01904160009382148

Cited by 47 publications

(26 citation statements)

References 21 publications

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“…For example, graminaceous species release phytosiderophores for the mobilization of Fe and other metals such as Zn, Ni and Cd (Marschner, 1995;Römheld and Awad, 2000). On the other hand, when exposed to a phosphorus deficiency, white lupin plants usually produce clusters roots, which exude large amounts of citric and malic acids (Neumann et al, 1999).…”

Section: Release Of Heavy Metals Into the Soil And Distribution Withimentioning

confidence: 99%

Partitioning of zinc, cadmium, manganese and cobalt in wheat (Triticum aestivum) and lupin (Lupinus albus) and further release into the soil

Page

Bayon

Feller

2006

Environmental and Experimental Botany

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The uptake and redistribution of the heavy metals zinc, cadmium, manganese and cobalt are relevant for plant nutrition as well as for the quality of harvested plant products. In the experiments reported here, seedlings of wheat (Triticum aestivum L.) and white lupin (Lupinus albus L.) were radiolabelled for 24 h with 65 Zn, 109 Cd, 54 Mn and 57 Co via one seminal root (wheat) or via the main root (lupin). Plants were afterwards grown on rhizoboxes containing soil. Samples were collected throughout the experiment and analysed afterwards for their radionuclide contents. A strong retention in the labelled part of the root was observed for 57 Co in wheat and lupin and for 109 Cd in lupin, while 65 Zn and 54 Mn were transported to the shoot in both plants. While 65 Zn was redistributed via the phloem from older to younger leaves, 54 Mn accumulated in the first leaves and no major redistribution within the shoot was observed.109 Cd was present in the shoot of wheat but not in the shoot of lupin. The redistribution of 65 Zn, 109 Cd, 54 Mn and 57 Co in the phloem differed between wheat and lupin. The 65 Zn content in the wheat roots appearing after the labelling phase represented 34% of the total content in the plant at the end of the experiment and less than 3% remained in the labelled root, while a high percentage of 65 Zn was retained in the originally labelled part of the main root of lupin. Smaller quantities of 109 Cd, 54 Mn and 57 Co accumulated in all parts of the root system of wheat and lupin. Nevertheless, heavy metals were found in rhizosphere soil (1-2 mm soil around the roots) and bulk soil (no contact with roots) from both plants. Higher quantities of heavy metals were found in the rhizosphere soil close to the labelled part of the root.65 Zn was present in large quantities in the rhizosphere soil close to all parts of the root system of wheat. For both plants, 65 Zn, 109 Cd, 54 Mn and 57 Co were found in the bulk soil indicating that the plant itself might play a role in the redistribution of heavy metals in the soil around its own roots. Phloem-mobile elements may be transported to growing parts of the root system and may reach deeper soil layers. The redistribution of heavy metals in the soil may be in vertical and horizontal directions, at least as far as the root system grows.

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Section: Release Of Heavy Metals Into the Soil And Distribution Withimentioning

confidence: 99%

Partitioning of zinc, cadmium, manganese and cobalt in wheat (Triticum aestivum) and lupin (Lupinus albus) and further release into the soil

Page

Bayon

Feller

2006

Environmental and Experimental Botany

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“…This could be due to a lower availability of Fe in soil B, which is basic and calcareous, compared to the slightly acid soil A. To face a Fe deficiency, ryegrass growing on the calcareous soil may excrete more phytosiderophores and mobilize more Cd than that growing on the slightly acid soil A (Awad et al, 1999;Awad and Ro¨mheld, 2000;Ro¨mheld and Awad, 2000;Treeby et al, 1989).…”

Section: Cadmiummentioning

confidence: 92%

“…They solubilize Fe and they may be involved in the mobilization of other metals, with which they have relatively strong binding constants (Murakami et al, 1989). Phytosiderophores have been shown to mobilize Cd, Cu, Mn, Ni and Zn (Awad et al, 1999;Awad and Ro¨mheld, 2000;Mench and Fargues, 1994;Ro¨mheld and Awad, 2000;Shenker et al, 2001;Treeby et al, 1989;Zhang et al, 1989Zhang et al, , 1991a. As a consequence, excretion of phytosiderophores could explain the highest L Cd values found for ryegrass grown in soil B.…”

Section: Cadmiummentioning

confidence: 96%

Quantifying the Effect of Rhizosphere Processes on the Availability of Soil Cadmium and Zinc

Sterckeman

Duquène²,

Perriguey³

et al. 2005

Plant Soil

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Our purpose was to quantify the effect of rhizosphere processes on the availability of soil cadmium and zinc to various plant species. E values for Cd and Zn were measured on two contaminated soils differing mainly in their pH (6.2 and 8.1). L values were measured for six plant species with contrasting metal uptakes. The difference between E and L values quantifies the mobilization of the element which was non-phyto-available prior to cultivation. For Zn, L values were 1.2 to 5.6 times greater than the E values, depending on the plant species. The increase in Zn availability was greater in the basic soil. For Cd, L values in the basic soil were 1.1 to 2 times greater than the E value. In the slightly acid soil, plants did not enhance the cadmium availability. The mobilization of non-labile metal could be due to exudates from roots or microflora, phytosiderophores being responsible for the highest mobilization. The lower availability of Fe or Zn could explain the greater mobilization in the basic soil.

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“…It has been shown that phytosiderophore release is also triggered under conditions of Zn deficiency (Tolay et al, 2001). Although, with high affinity for ferric iron, phytosiderophores of the mugineic acid family also chelate other heavy metals, such as Cu, Mn, and Zn as well as other non-essential metals (Treeby et al, 1989;Römheld and Awad, 2000).…”

Section: Organic Acids and Amino Acidsmentioning

confidence: 99%

“…Studies have demonstrated that the primary constituents of root exudates are low-molecular weight organic acids that play essential roles in making sparingly soluble soil Fe, P, and other metals available to growing plants (Römheld and Awad, 2000;Yang and Crowley, 2000). Various plant species have developed mechanisms to enable them to grow on acid soils where toxic levels of aluminum, Al 3+ , can limit plant growth.…”

Section: Organic Acids and Amino Acidsmentioning

confidence: 99%

Heavy Metal Stress

Gašić

Korban

2006

Physiology and Molecular Biology of Stress Tolerance in Plants

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Significance of root exudates in acquisition of heavy metals from a contaminated calcareous soil by graminaceous species

Cited by 47 publications

References 21 publications

Partitioning of zinc, cadmium, manganese and cobalt in wheat (Triticum aestivum) and lupin (Lupinus albus) and further release into the soil

Partitioning of zinc, cadmium, manganese and cobalt in wheat (Triticum aestivum) and lupin (Lupinus albus) and further release into the soil

Quantifying the Effect of Rhizosphere Processes on the Availability of Soil Cadmium and Zinc

Heavy Metal Stress

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