Effects of different concentration copper on pigment content and antioxidase system of Spirodela polyrrhiza and Lemna minor
通过水培试验研究了不同浓度的重金属Cu对紫背萍(Spirodela polyrrhiza)和青萍(Lemna minor)的色素含量和抗氧化酶系统的影响.结果表明,低浓度Cu(0.056 mg·L-1)的处理下，紫背萍和青萍的叶绿素a、叶绿素b和叶绿素(a+b)的含量均出现不同程度的增加，分别高出其对照11％、46％、22％和8％、15％、11％，而在高浓度Cu(0.18～5.60 mg·L-1)的处理下，上述色素含量均显著下降，平均下降幅度分别达63％、62％、65%和46％、44％、45％.紫背萍体内丙二醛(MDA)含量为青萍的2.57倍.两种浮萍的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的活性均随Cu浓度的增加而呈先升后降的趋势，紫背萍体内3种酶活性在Cu浓度仅为0.18 mg·L-1时即达峰值，随后则大幅下降，而青萍体内3种酶活性却在Cu浓度分别升高到0.56、1.0和1.0 mg·L-1时才达到峰值.可见，在Cu胁迫下，紫背萍受Cu毒害较青萍深，且其体内抗氧化酶系统也较青萍敏感.
The study with water culture showed that when treated with 0.056 mg Cu·L-1,the chlorophyll a,b and (a+b) contents in Spirodela polyrrhiza and Lemna minor were increased by 11%,46% and 22%,and 8%,15% and 11%,while under 0.15～5.6 mg Cu·L-1,the contents were decreased by 63%,62% and 63%,and 46%,45% and 45%,respectively,compared with no copper added.The malondialdehyde (MDA) content in S.polyrrhiza was 2.75 times higher than that in L.minor averagely.The superoxide dismutase (SOD),catalase (CAT) and peroxidase (POD) activities in both S.polyrrhiza and L.minor all increased first,but decreased then with increasing copper concentration.For S.polyrrhiza,the activities of test enzymes were the highest at 0.18 mg Cu·L-1,but for L.minor,only when the Cu concentrations were up to 0.56,1.0 and 1.0 mg·L-1,the activities of SOD,CAT and POD got to their peak values,respectively.It was concluded that higher concentrations of copper caused more damage to S.polyrrhiza than to L.minor,and the antioxidase system of the former was much more sensitive to the copper stress than that of the latter.
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