Cu2+对拟南芥根的局部毒性及诱导DNA损伤和细胞死亡

摘要

We investigated the effect of different CU2+ concentrations in the root medium on root growth,reactive oxygen species (ROS) accumulation,antioxidative response,DNA damage,plasma membrane integrity and cell viability in roots of Arabidopsis thaliana,and the toxicity range was explored with split-root technique.Primary root length was significantly inhibited.Cu2+ enhanced the activities of antioxidant enzymes,induced ROS accumulation and DNA damage,and reduced plasma membrane integrity.Cell death was significantly increased with increased concentration of Cu2+.ROS accumulation was significantly and positively correlated with the activities of total superoxide dismutase,catalase,peroxidase and ascorbate peroxidase.ROS accumulation increased linearly with DNA damage,plasma membrane integrity and cell viability.In the split-root experiment,root growth was inhibited in culture medium supplemented with 75 μmol.L-1 Cu2+; however,roots were not inhibited in medium without supplementary Cu2+.ROS accumulation and cell death took place in only half the dish,so Cu2+ toxicity was local,not systemic.Local ROS accumulation in roots likely mediates the cell death caused by CU2+ stress.%该文探讨了不同浓度的CU2+胁迫对拟南芥(Arabidopsis thaliana)根生长、活性氧(ROS)积累、抗氧化酶活性、质膜完整性和细胞活性的影响,通过分根实验初步分析了CU2+毒性效应的影响范围.结果表明,CU2+胁迫可显著抑制拟南芥主根伸长,诱导ROS积累及DNA损伤,促发抗氧化酶活性升高,破坏质膜完整性,且Cu2+浓度越高,毒性效应越明显,在高浓度CU2+胁迫下细胞活性显著降低.分析各参数之间的关系,表明ROS的积累与超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)及抗坏血酸过氧化物酶(APX)的活性呈显著正相关;ROS积累与DNA损伤、质膜完整性、细胞活性之间具有显著的近线性关系.分根实验结果表明,只有在添加重金属Cu2+(75 μmol·L-1)一侧培养基中的根生长受抑制,并出现ROS积累、细胞死亡,暗示Cu2+对拟南芥根系的局部毒性效应可能是由于ROS的局部性积累导致受胁迫根系一侧的细胞死亡所引起的.