Cadmium-induced oxidative stress and antioxidative enzyme response in water hyacinth and salvinia

The reactive oxygen species generation, lipid peroxidation and antioxidative enzyme response of water hyacinth and salvinia to Cd were evaluated. Cadmium was absorbed/accumulated mainly in the roots, but significant amounts also translocated to the leaves. No Cd effect on dry weight was detected, although toxicity symptoms were visible. Superoxide and H2O2 concentrations increased, in addition to lipid peroxidation in both species, especially in the leaves of salvinia. In general, antioxidative enzyme activities were reduced in both species following Cd treatment, especially in salvinia. Glutathione peroxidase (GPX, EC 1.11.1.9) activity decreased in water hyacinth but increased in salvinia. Glutathione S-transferase (GST, EC 2.5.1.18) activity increased in the leaves but decreased in the roots of both species. So, Cd induced ROS generation/accumulation, but the antioxidative enzymes were not able to combat the Cd-induced oxidative injury in these two species. Nevertheless, water hyacinth consistently showed a higher tolerance to Cd than salvinia.