Copper-induced oxidative stress in maize shoots (Zea mays L.): H2O2 accumulation and peroxidases modulation.

The effect of copper excess on growth, H2O2 level and peroxidase activities were studied in maize shoots. Ten-day-old seedlings were cultured in nutrient solution that contained Cu2+ ions at various concentrations (50 and 100 microM) for seven days. High concentrations of Cu2+ ions caused significant decrease both in matter production and elongation of maize shoots. In addition, treatment with CuSO4 increased levels of H2O2 and induced changes in several peroxidase activities. Moreover, the disturbance of the physiological parameters was accompanied by the modulation of the peroxidase activities: GPX (Guaiacol peroxidase, EC 1.11.1.7), CAPX (Coniferyl alcohol peroxidase, EC 1.11.1.4) and APX (Ascorbate peroxidase, EC. 1.11.1.11). Furthermore, this modulation becomes highly significant, especially, in the presence of 100 microM of CuSO4.