Toxicity, metal uptake, and accumulation of phytochelatins in silene vulgaris exposed to mixtures of cadmium and arsenate

The mixture effects of arsenate and cadmium were studied in Silene vulgaris (Moench) Garcke. The results show that the toxicity of the mixtures, measu red as inhibition of root elongation, increased with increasing concentrati ons, ranging from nonadditive or slightly additive to synergistic. The elem ents did not influence each other's uptake. This was as expected, consideri ng the differences in uptake mechanisms between both elements. Concentratio ns of detoxifying phytochelatins (PCs) were additive, with respect to both external and root-internal metal concentrations. However, at high exposure concentrations, the plants metabolism collapsed, resulting in very low PC c oncentrations.