Assessment of antioxidant enzymes in leaves and roots of Phaseolus vulgaris plants under cadmium stress

The aim of this work was to evaluate the response of Phaseolus vulgaris plants to oxidative stress by cadmium in leaves and roots at different concentrations (0 (control), 0.25, 0.50 and 1 mu M). We assessed oxidative stress by the contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA), as well as protein content. Likewise, we determined the antioxidant enzymatic activity of the superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) enzymes. The results demonstrated a decrease in protein content of roots and leaves, starting with the addition of 0.25 mu M Cd, but the MDA content and H2O2 levels increased with the addition of 0.25, 0.50 and 1 mu M Cd, this due to the formation of reactive oxygen species. The SOD, APX and GPX enzymatic activity increased in roots treated with 0.25 mu M Cd, but these enzymes decreased to higher concentrations (0.50 and 1 mu M). On the other hand, the activity of CAT increased in leaves exposed to 0.5 and 1 mu M of Cd. These results indicate that these antioxidant enzymes can act simultaneously in the elimination of reactive oxygen species.