Effects of Rare Earth on Oxidative Damage and Redox System of Wheat Seedling Leaves under Water Stress

After treated with low concentration of La3+, the rate of producing active oxygen free radical, the relative permeability of cell membrane, the contents of bivalent iron ion in wheat seedling leaves under water stress were determined. The results show that in wheat seedling leaves, feasible concentrations of La3+ decreases the accumulation of active oxygen free radical, inhibits the increase of the relative permeability of cell membrane, reduces the content of peroxidation product MDA of membrane lipid, and prevents the plant cell producing more bivalent iron ion which can catalyzed the reaction of Haber-weiss and Fenton to produce more superoxide anion. In addition, purified plasma membrane was isolated by aqueous two-phase partitioning from wheat seedling leaves. The reduction rate of Fe（CN）63- by purified plasma membrane in La3+-treated wheat seedling leaves is different from those in the absence of La3+ under water stress. The changing trend of the redox activity to La3+ is similar to that of the content of Fe2+. The results reveal that extraneous La3+ can alleviate the damages of cell membrane caused by water stress via promoting the activity of redox system and the ability of eliminating ROS in wheat seedling leaves.