Differential effect of equal copper, cadmium and nickel concentration on biochemical reactions in wheat seedlings

Influence of 75 μM copper (Cu), cadmium (Cd) and nickel (Ni) on growth, tissue metal accumulation, non-protein thiols (NPT) and glutathione (GSH) contents, membrane damage, lipid peroxidation and protein oxidation as well as protease, glutathione S-transferase (GST) and peroxidase (POD) activities were studied in the shoots and roots of wheat seedlings after 7 days of metal exposure. The greatest growth reduction was found in response to Cu treatment; however accumulation of this metal in the wheat tissues was the lowest compared to the other metals used. All metals caused enhancement of electrolyte leakage from cells as well as increased lipid peroxidation and protein carbonylation. Proteolytic activity was enhanced only in Cu-exposed seedlings and in the roots it coincided with elevated protein carbonylation. The most pronounced increase in POD activity in the shoots was found after Ni treatment while in the roots in response to Cu. In contrast to Cu, application of Cd and Ni resulted in accumulation of NPT and induction of GST activity, which suggested involvement of these mechanisms in metal tolerance in wheat.