重金属胁迫引起的水稻和小麦幼苗DNA损伤

DNA Damage Caused by Heavy Metal Stress in Rice and Wheat Seedlings

供试浓度的重金属Cu2 + 、Cd2 + 和Hg2 + 能在不同程度上导致水稻和小麦DNA损伤。 (1)Hg2 + ≥ 0 .0 2 5mmol L、Cu2 + 和Cd2 + ≥ 0 .1mmol L处理使水稻幼苗期外DNA合成速率显著高于对照 ,且当Cu2 + 、Cd2 + 和Hg2 + 浓度进一步增高时 ,水稻幼苗期外DNA合成速率呈现先上升而后较最大值有所下降的规律。 (2 ) 0 .1～1.0mmol L的Cu2 + 及 0 .1mmol L的Cd2 + 、Hg2 + 能引起水稻、小麦叶内DNA和蛋白质交联 ,并且这种和DNA交联的蛋白质易被胰蛋白酶水解。 (3) 0 .1～ 1.0mmol L的Hg2 + 及 1.0mmol L的Cd2 + 还能使水稻。

The DNA damage caused by different concentration of Cu 2+ ,Cd 2+ or Hg 2+ was investigated in rice ( Oryza sativa cv.Yangdao No.6) and wheat( Triticum aestivum cv. Yangmai No.10) seedlings. The results were as follows: (1) Cu 2+ and Cd 2+ ≥0.1 mmol/L or Hg 2+ ≥0.025 mmol/L caused the rate of unscheduled DNA synthesis in rice seedling to be higher than that in control. With the increase in Cu 2+ , Cd 2+ and Hg 2+ concentration, the rate of unscheduled DNA synthesis increased, and it began to decrease when the Cu 2+ and Cd 2+ concentrations were higher than 0.3 mmol/L(Fig.1). (2) DNA protein cross linking in rice and wheat leaves was induced by 0.1 to 1.0 mmol/L Cu 2+ or 0.1 mmol/L Cd 2+ and Hg 2+ . The protein which cross linked to DNA was easily hydrolyzed by pancreatic trypsin (Fig.2). (3) 0.1 to 1.0 mmol/L Hg 2+ or 1.0 mmol/L Cd 2+ might induce DNA interstrand cross linking in the leaves of rice and wheat(Figs.3,4).