Symptomatic parameters of oxidative stress and antioxidant defense system in Phaseolus vulgaris L. in response to copper or cadmium stress

The impacts of varied concentrations of copper (Cu) or cadmium (Cd) on the oxidative stress experienced by shoots and roots of Phaseolus vulgaris plants were examined in this study. Hydrogen peroxide (H2O2), lipid peroxidation, electrolyte leakage, as well as ascorbate (AsA), reduced glutathione (GSH) and total phenolic contents were significantly increased by all concentrations of the heavy metals used, except for 10− 6 M concentration of Cu which appeared to induce an insignificant increase above the control value. On the other hand, anthocyanins content showed variable decreases in response to all Cu or Cd treatments. In heavy metals-stressed plants, fluctuations in the determined antioxidant enzyme activities were observed as compared with controls. Thus, although superoxide dismutase (SOD) and catalase (CAT) activities were apparently increased in response to the low heavy metal concentrations, yet their apparent decreased activities were operative upon administration of high concentrations of Cu or Cd. On the other hand, the dynamic activities of glutathione reductase (GR) and ascorbate peroxidase (APX) were significantly increased in all heavy metals-stressed plants, above the control levels, during the period of the experiment. The present results are discussed in light of current literature and in relation to interference of the used concentrations of Cu or Cd heavy metals and their involvement in oxidative stress.