Cadmium Stress Induced Changes in Antioxidant Enzymes, Lipid Peroxidation and Hydrogen Peroxide Contents in Barley Seedlings

Cadmium pollution is a problem of increasing significance for ecological, nutritional and environmental reasons. Different plant species and varieties show a wide range of plasticity in Cadmium tolerance, from a high degree of sensitivity to the hyper-accumulating phenotype of some tolerant plants. To avoid Cadmium toxicity, plants adopt various defense strategies. The present study was undertaken to assess and investigate the antioxidant responses of barley (Hordeum vulgare L.) to cadmium treatment, seedlings of barley were grown in increasing concentrations of CdCl_2 ranging from 25-100 μM, for up 14 days in a hydroponic system. The results showed that CdCl_2 reduce pigment content and caused oxidative damage as characterized by increased total soluble protein, Malondialdehyde (MDA) and Hydrogen peroxide (H_2O_2) contents. Under cadmium stress, the activities of antioxidative enzymes, including Ascorbate Peroxidase (APX), Peroxidase (POD) and Catalase (CAT) were increased considerably in plant tissues. The present results allow us to conclude that the barley plants showed a negative response to cadmium toxicity. The physiological and biochemical process in plants was significantly affected by stress of CdCl_2. To deal with the cadmium induced oxidative stress, barley plants activated antioxidant enzymes to diminish the Reactive Oxygen Species (ROS).