RESPONSE OF ANTIOXIDANT ENZYMES IN POPULUS x CANESCENS UNDER CADMIUM STRESS

Hydroponic experiments were conducted to study the tolerance of Populus canescens were exposed to different levels of Cd2+ (0, 10, 30, 50, and 70 mu M/L) as compared to the control. After 28-day (s) of Cd2+ exposure it was found that the biomass of all tissues in P. x canescens was unaffected by Cd2+ exposure, Cd2+ concentration 70 mu M/L, To investigate the possible effects of Cd ions in the generation of oxidative stress, we detected the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) in the different tissues of Populus canescens, it was found that 1) oxidative stress in P. canescens took place at different concentrations of Cd ions and with increasing of exposure time as evidenced by the malondialdehyde (MDA) and H2O2 concentrations; and 2) antioxidant enzymes activities were also stimulated by Cd treatment and were associated with changes in ascorbate; Among all tissues, significant increases of GR activities and significant changes in the ascorbate (ASC) and glutathione (GSH) pool were observed, which suggest that Cd2+ can be added to the list of stresses. The results in this study suggest that the growth of P. canescens in the presence of Cd metal showed a concentration-dependent oxidative stress situation in the different tissues, as a result of the inhibition of the antioxidant systems.