Phytochelatins and heavy metal tolerance
1999
Leopold, I. | Gunther, D. | Schmidt, J. | Neumann, D.
The induction and heavy metal binding properties of phytochelatins in heavy metal tolerant (Silene vulgaris) and sensitive (tomato) cell cultures, in water cultures of these plants and in Silene vulgaris grown on a medieval copper mining dump were investigated. Application of heavy metals to cell suspension cultures and whole plants of Silene vulgaris and tomato induces the formation of heavy metal-phytochelatin-complexes with Cu and Cd and the binding of Zn and Pb to lower molecular weight substances. The binding of heavy metal ions to phytochelatins seems to play only a transient role in the heavy metal detoxification, because the Cd-and Cu-complexes disappear in the roots of water cultures of Silene vulgaris between 7 and 14 days after heavy metal exposition. Free heavy metal ions were not detectable in the extracts of all investigated plants and cell cultures. Silene vulgaris plants grown under natural conditions on a mining dump synthesize low molecular weight heavy metal binding compounds only and show no complexation of heavy metal ions to phytochelatins. The induction of phytochelatins is a general answer of higher plants to heavy metal exposition, but only some of the heavy metal ions are able to form stable complexes with phytochelatins. The investigation of tolerant plants from the copper mining dump shows that phytochelatins are not responsible for the development of the heavy metal tolerant phenotypes.
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