Cadmium-induced Peroxidation and Production of Sulfur-related Complex in Roots of Narcissus tazetta var. chinensis

Effect of varied concentrations(i.e.,0, 0.5, 2, 4, 8, and 25 mgL-1) of cadmium (Cd) on the membrane lipid peroxidation, superoxide dismutase (SOD), peroxidase (POD), non-protein sulfydryl (NPT), and glutathione (GSH)in the roots of daffodil, Narcissus tazetta var. chinensis, were studied with a hydroponic culture. The study aimed to gain information for the cultivation, as well as selection of appropriate phytoremediation on the heavy metal stresses for the plants.It was found that (a) the content of root malondialdehyde (MDA) increased as Cd concentration increased; (b) at 4-25 mgL-1, Cd induced a significant increase on hydrogen peroxidein the roots; (c) as Cd concentration increased, SOD activity decreased initially and followed by an increase,while POD decreased continuously with a significantly lower level than that of control when Cd concentration reached 4-25 mgL-1; (d) GSH greatly increased with 8-25 mgL-1 Cd, while NPT drastically decreased with the presence of 0.5 mgL-1 or 25 mgL-1 Cd. It appeared that, even at low level, Cd already imposed oxidative stress on daffodil. As Cd concentration increased, the stress worsened. Underprolonged Cd stress, the anti-oxidation enzymatic activity was suppressed resulting in a lowered capacity of the plants to resist the stress. On the other hand,when encountered high Cd stress, the daffodil plant would synthesize GSH to improve its resistance to the adverse condition.