Cadmium-induced oxidative stress and protection by L-Galactono-1, 4-lactone in winter wheat (Triticum aestivum L.)

Two hydroponic culture experiments were conducted to investigate cadmium (Cd)-induced oxidative stress in winter wheat (Triticum aestivum L.) seedlings and the effects of L-Galactono-1, 4-lactone (GaIL), the biosynthetic precursor of the antioxidant ascorbate (AsA), on the oxidative stress induced by Cd. In experiment 1, with application of Cd (0, 10, 25, 50 mu M) in nutrient solution, hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels as well as membrane permeability in both shoots and roots were significantly increased, indicating Cd-induced oxidative stress and lipid peroxidation as well as plasma-membrane damage in the plants. In experiment 2, H2O2 levels in plants exposed to Cd were significantly reduced by the addition of GaIL (25 mM), associated with increased activities of peroxidase (POD), indicating that GaIL alleviated the oxidative stress induced by Cd. Unexpectedly, however, the MDA levels were not reduced by the addition of GaIL. Does Cd also induce lipid peroxidation directly besides via formation of reactive oxygen species (ROS)? This needs further study.