铜、镉、汞对水稻幼苗抗氧化酶活性的影响

目的:研究必需元素Cu2+和非必需元素Cd2+、Hg2+对水稻幼苗生长的影响,探讨水稻抵抗重金属毒害的机理.方法:用质量浓度为0.25 mmol/L、0.5 mmol/L、1.0 mmol/L重金属离子溶液滴灌水稻幼苗,测定处理后幼苗根和叶的长度,蛋白质和叶绿素含量,过氧化氢酶、超氧化物歧化酶和过氧化物酶活性及过氧化物酶和超氧化物歧化酶同工酶的表达变化.结果:重金属离子抑制水稻幼苗生长,降低幼苗根和叶可溶性蛋白含量,增强了根、叶POD活性和根系SOD活性；Cu2+增强幼苗叶SOD活性,而Cd2+和Hg2+抑制幼苗叶SOD活性.不同浓度Cd2+降低水稻幼苗叶绿素含量；不同浓度Hg2+降低幼苗根和叶CAT活性；Cd2+增强根CAT活性,但抑制叶CAT活性；随着Cu2+浓度增大而逐渐减弱根和叶CAT活性.POD与SOD同工酶电泳结果与其活性检测相一致.结论:Cu2+、Cd2+、Hg2+处理对水稻幼苗POD、SOD和CAT活性的影响与重金属种类和浓度有关并存在器官特异性.水稻幼苗表现出抗氧化活性增加和减少两种情况,说明抗氧化系统不仅具有解毒功能,同时还是Cd2+、Cu2+和Hg2+对植物产生毒性的作用位点.

Effects of Cu2+,Cd2+,Hg2+ on the Antioxidant Enzyme Activities of Rice Seedlings

Objective:In order to investigate rice resistance mechanisms to different types of heavy metal ion,the effects of Cu2+,Cd2+,Hg2+ on several physiological indexes of rice seedling were studied.Method:The rice seedlings were treated with Cd2+,Cu2+,Hg2+ with different concentration including 0 mmol/L,0.25 mmol/L,0.5 mmol/L,1.0 mmol/L,the length of root and leaf,the contents of chlorophyll and protein,the activities of catalase,superoxide dismutase and peroxidase,and the changes of isoenzyme expression were measured.Result:The growth of rice seedlings was inhibited,soluble protein content in roots and leaves decreased,POD activity in root and leaves and SOD activity in root enhanced,treated by heavy metal ions.Cu2 + enhanced the SOD activity of leaves,however,Cd2 + decreased the SOD activity in leaves.Different concentrations of Cd2 + reduced the chlorophyll content in rice seedlings.Different concentrations of Hg2 + reduced the CAT activity in roots and leaves,Cd2+ enhanced the CAT activity of the root,but inhibit the CAT activity of leaves.With the increase of Cu2+ concentration,the CAT activity in roots and leaves gradually decreased.The electrophoresis of isozymes of POD and SOD were consistent with their activities.Conclusion: Cu2+,Cd2+ and Hg2+ have some effects on the activities of CAT,POD and SOD in rice seedlings.This effect was related with the type and concentration of heavy metals,and has organ specificity.Rice seedlings can increased or decreased antioxidant activity.So antioxidant system not only has detoxification function,but also was toxicity sites of Cu2+,Cd2+ and Hg2+ in plant.