The Activity of the Antioxidative System in Cadmium-Treated Arabidopsis thaliana

Abstract

Changes in the content of reactive oxygen species (ROS) and activity of the antioxidant system were measured in leaves of Arabidopsis thaliana (L.) Heynh exposed to Cd2+. Mature plants growing in the nutrient solution were treated with Cd2+ at different concentrations (0, 5, 25, 50, 100 μM). An increase of O2.- content in leaves was observed at 5, 25 and 50 μM Cd2+. A strong accumulation of H2O2 was found only at the lowest Cd2+ concentration. The content of OH*. was high at 50 and 100 μM Cd2+. Superoxide dismutase (SOD) activity was always higher in Cd2+-treated plants than in control. Catalase (CAT) activity decreased with increasing Cd2+ concentration in the nutrient solution. Guaiacol peroxidase (POX) activity was particularly high at the lowest and highest Cd2+ concentrations and ascorbate peroxidase (APX) activity additionally at 50 μM Cd2+. Enhanced activity of monodehydroascorbate reductase (MDHAR) and strong reduction in ascorbate (AA) content were observed at 25 μM Cd2+. Glutathione reductase (GR) activity was always higher than in control but decreased as Cd2+ concentration increased. However, it was accompanied by gradual content increase of SH-groups.