Pb对匍匐翦股颖根系超氧化物歧化酶活性的影响

Effects of Lead on the Activity of Superoxidate Dismutase (SOD) in the Roots of Creeping Bent Seedlings

通过Pb离子浓度胁迫与处理时间两因素试验方案,利用甲基氮蓝四唑(NBT)光密度测定法测定了匍匐翦股颖(Agrotistolonifera)根系细胞内超氧化物歧化酶(SODs)活性,并用统计分析软件SPSS13.0中的GenearLinearModel模块,对试验数据进行了F测验,用LSD法对各水平间进行多重比较检验。结果表明,重金属Pb各处理浓度对SODs的影响均达到极显著水平,处理后SODs水平显著上升,到第4d时达到最高值,处理第3d与第4d之间未达显著水平,第1、2d与第3、4、5d之间达到极显著水平发现低浓度(<2.5mmol·L-1)Pb处理可促使根系细胞积极的防御策略,使细胞SODs水平持续增加;高浓度(>10.0mmol·L-1)处理使SODs活性在早期上升,第4d后SODs开始下降,其主要原因是Pb离子胁迫产生的超量自由基导致酶失活效应所致。

The protective system of plant cells can be overwhelmed for increasing reactive oxygen species （ROS） formation under stress conditions. Heavy metal pollutant is one of the stress conditions in the nature. With a cell, the superoxide dismutase （SOD） constitutes the first line for defending against ROS in the detoxification enzymes, Creeping bent （Agrositis stolonifera） is one of the most important lawn plant in China, widely used in gardening construction and environmental rehabilitate in south China, Study the activity of SOD in creeping bent root cells can explore the mechanism of the plant adaptability to heavy metal ions. Exposed to 0.5, 1.0, 2.5, 5.0 and 10.0 mmol· L^-1 of lead for 5 d in hydroponic culture, the distribution of metal, and the activity of SOD in creeping bent seedlings were determined and analyzed by means of two factor experimental project means. The results showed that the activity of the detoxification enzymes in roots cells of the plant could be significantly affected by lead ion stress. The activity of SOD in cells increased gradually at low concentration （〈2.5 mmol·L^-1） of lead ion, which may be an active strategy to protecting root cells under lead-induced oxidative stress. At high concentration （〉 10.0 mmol·L^-1） of lead ion, the initially increased activity of SOD, however, declined after 4 d treatment, since the ROS induced by lead arouse the denaturalization of detoxification enzymes.