金鱼藻抗氧化系统对镉胁迫的响应

目的]研究镉对金鱼藻生长的影响和金鱼藻抗氧化酶对胁迫伤害的响应。方法]用不同浓度的氯化镉溶液(纯镉离子浓度分别为0、0.2、1.0、2.0 mg/L)处理金鱼藻,并分别于处理后1、2、4、8 d测定处理后植株叶绿素和可溶性蛋白含量、镉的积累量、抗氧化酶活性以及氧化胁迫参数等指标。结果]金鱼藻体内镉的积累量随胁迫浓度和时间的增加而增加,但积累速率随胁迫浓度和时间的增加而降低;抗氧化酶系统对镉胁迫具有应激反应,当镉浓度小于1.0 mg/L时,超氧物歧化酶(SOD)活性、过氧化氢酶(CAT)活性均先上升,4d后又下降,而当镉浓度大于2.0 mg/L时,上述酶活性下降,同时,H2O2含量、MDA含量上升。结论]低浓度镉可以诱导抗氧化酶活性,抵御氧化胁迫,但随着隔浓度的增加,抗氧化酶活性降低,植物受到氧化胁迫伤害。

Response of the Antioxidant System of Ceratophyllum demersum L.to Cadmium Stress

Objective] To study the influence of Cd on the growth of C.demersum and the response of C.demersum antioxidase to Cd stress.Method]C.demersum was exposed to various concentrations of CdCl2(0,0.2,1.0 and 2.0 mg/L pure cadmium),and then its chlorophyll content,soluble protein content,Cd accumulation,antioxidase activity and oxidative stress parameters were determined 1,2,4 and 8 d after the treatment.Result] Accumulation of Cd was found to be a concentration and duration dependent phenomenon,the antioxidase system showed response to Cd stress.When Cd concentration was less than 1.0 mg/L,the SOD and CAT activities firstly improved and then declined after four days;but when the Cd concentration was above 2.0 mg/L,the SDO and CAT activities declined,which was accompanied by increase in the levels of H2O2 and MDA.Conclusion] Low concentration of Cd would induce the antioxidase activity and prevent oxidant stress,but with the increasing Cd concentration,the antioxidase activity declined,and the plants were damaged under oxidant stress.