铅、镉单一及复合胁迫对生菜幼苗抗氧化酶及亚细胞结构的毒性效应  

Toxicity of Single and Combined Pb and Cd Stress on Antioxidant En-zymes and Subcellular Structure of Lettuce

作　　者：林琳[1] 旦增卓嘎 吴玲玲[1] Lin Lin;Tenzin Dolker;Wu Lingling(College of Environmental Science and Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学环境科学与工程学院,上海200092

出　　处：《生态毒理学报》2022年第2期337-348,共12页Asian Journal of Ecotoxicology

基　　金：国家重点研发计划“场地土壤污染成因与治理技术”重点专项“铅锌冶炼场地土壤多重金属长效稳定修复材料、技术与装备(2019YFC1805205)”。

摘　　要：为阐明重金属铅(lead,Pb)、镉(cadmium,Cd)单一及复合胁迫对生菜幼苗生长发育过程中抗氧化酶及亚细胞结构的影响,本研究通过实验室水培实验,探讨生菜幼苗生长时期,不同浓度Pb(0、0.2、0.5、1和5 mg·L^(-1))和Cd(0 mg·L^(-1)和0.02 mg·L^(-1))单一及复合胁迫下对生菜叶片中叶绿素a含量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)和过氧化物酶(POD)活性以及亚细胞结构的毒性效应。研究结果表明:(1)在重金属Pb、Cd单一及复合胁迫下,随着暴露浓度的增加,叶绿素a的含量在第6天、第10天和第14天均表现出“低促高抑”的趋势;(2)在重金属Pb、Cd单一及复合胁迫下植物叶片细胞中的抗氧化酶对胁迫做出了反应应答,SOD、POD和APX的水平有显著性变化。其中,在6~14 d时Pb、Cd单一及复合胁迫下,各暴露组SOD活性相较于对照组受到抑制,POD活性(除Pb 0.02 mg·L^(-1)胁迫下)相较于对照组被诱导,APX活性在暴露前期(6 d和10 d)呈现出“低促高抑”的趋势,在暴露后期(14 d)随暴露浓度增加,APX的活性相较于对照组受到抑制;此外,随着胁迫程度的增加,生菜叶片中MDA的含量随之增加;(3)当暴露至14 d时,在Pb 5 mg·L^(-1)+Cd 0.02 mg·L^(-1)胁迫下,Pb、Cd对生菜叶绿素a含量的毒性效应为协同作用,其余胁迫条件下均表现为拮抗作用;(4)在Pb、Cd单一及复合胁迫下,生菜叶片细胞中叶绿体的结构均遭到破坏,线粒体空泡化,染色质出现不同程度的凝缩。The toxic effects of single and combined stress of lead(Pb)and cadmium(Cd)exposure on antioxidant enzymes and subcellular structure of lettuce was investigated in this study.On the basis of the Chinese water quality standard,Pb(0,0.2,0.5,1 and 5 mg·L^(-1))and Cd(0,0.02 mg·L^(-1))were designed in the hydroponic experiment of lettuce.The changes of antioxidant enzyme activities,chlorophyll a and lipid peroxidation contents were evaluated after exposure for 6,10 and 14 d,respectively.The results show that(1)under the single and combined stress of Pb and Cd,with the increase of exposure concentration,the content of chlorophyll a showed a trend of“activa-tion-inhibition”at 6,10 and 14 d;(2)under the stress of Pb and Cd,the activity of superoxide dismutase(SOD),a-scorbate peroxidase(APX)and peroxidase(POD)changed significantly.Among them,under single and combined stress of Pb and Cd for 6~14 d,the SOD activity of each exposure group was lower than that of control group,the POD activity(except 0.02 mg·L^(-1)Pb stress)was higher than that of control group.APX activity showed a trend of“activation-inhibition”at the early stage of exposure(6 d and 10 d).But in the later period of exposure(14 d),with the increase of exposure concentration,the activity of APX was lower than the control group.In addition,the malondialdehyde(MDA)content of lettuce leaves was increased with the increase of stress concentration;(3)when exposed for 14 d,under the stress of Pb 5 mg·L^(-1)+Cd 0.02 mg·L^(-1),the toxic effect of Pb and Cd on the content of lettuce chlorophyll a was synergistic,and the other conditions showed antagonism;(4)under the single and com-bined stress of Pb and Cd,the structure of chloroplast in lettuce leaves was destroyed,showing mitochondria vacu-olated and chromatin condensed to varying degrees.

关 键 词：铅 镉 生菜 抗氧化酶 亚细胞结构 

分 类 号：X171.5[环境科学与工程—环境科学]