Schlüsselwörter
(Englisch)
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Aluminium; heavy metals; organic acids; exudation; tree roots; poplar; birch; eucalypt; Douglas fir; ectomycorrhiza
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Forschungsprogramme
(Englisch)
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COST-Action 631 - Understanding and Modelling Plant - Soil Interactions in the Rhizosphere Environment
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Kurzbeschreibung
(Englisch)
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This project has the aim to investigate whether tree roots, similarly to many crop plants, exude organic acids at enhanced concentrations of Al or heavy metals. We propose to test 4 selected tree species, mycorrhizal and non-mycorrhizal, for mainly citrate, malate, and oxalate exudation upon exposure to elevated Al, Cu, Cd, and Pb concentrations. In addition, we will assess the influence of this exudation on metal mobility in the rhizosphere.
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Partner und Internationale Organisationen
(Englisch)
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AT, BE, BG, CY, CZ, DK, FI, FR, DE, EL, HU, IE, IT, NL, NO, PL, SK, SI, ES, SE, CH, UK
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Abstract
(Englisch)
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Poplars (Populus spp.) are increasingly used for the phytoremediation of polluted soils because of their high growth rates and efficient uptake potential for Al and heavy metals. However, only few studies have been carried out on the resistance and tolerance of poplars to metal stresses. Using aseptically grown poplar cuttings, the impacts of Al, Cu, and Zn stress on root exudates and on root apices were investigated. After 2 d of exposure to these metals, it was observed that elevated concentrations of Al induced the exudation of oxalate and citrate, Cu the exudation of oxalate, malate, and formate, and Zn the exudation of formate. The threshold concentrations were 500 µM for Al and Zn and 100 µM for Cu. Simultaneously to the increase of the organic acid exudations, significant increases of sulfate and the nutrient cations K+, Ca2+, and Mg2+ were recorded in the solutions. Significant positive correlations between the organic acids and sulfate or the cations indicated possible co-effluxes, and between the cations possible co-displacements by the added metals at the cell walls. Toxicity symptoms of the poplar roots were: a browning of the root apices, which occurred with Cu at 50 µM, with Zn at 500 µM, and with Al at 1000 µM; and a formation of callose in the root apices, but which was observed solely with Al at 500 µM or above
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Datenbankreferenzen
(Englisch)
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Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. +41 31 322 74 82 Swiss Project-Number: C02.0080
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