Cadmium toxicity induces lipid peroxidation and alters cytokinin content and antioxidant enzyme activities in soybean

The short-term effect of exposure (24 to 72 h) to various concentrations of CdCl2 on cytokinin content, lipid peroxidation, hydrogen peroxide level, and reduced glutathione content, as well as the activities of representative enzymes of the antioxidant defense system, were investigated in soybean. In addition, the deleterious effects of cadmium poisoning on soybean growth and photosynthetic pigment content were recorded. Exposure to cadmium significantly inhibited growth and severely reduced photosynthetic pigment content. Cadmium treatment was also found to increase lipid peroxidation and hydrogen peroxide levels, indicating that cadmium can induce an oxidative stress response in leaves. Inhibition of cytokinin fractions (zeatin and zeatine riboside) were also detected in all tested cadmium concentrations, zeatin being most severely affected. We also found that exposure to cadmium increased the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase and altered glutathione content. This is representative of a cadmium-induced defense mechanism required to cope with elevated oxidative stress.