【摘要】 在 3种不同浓度的NaCl (85mmol·L-1,170mmol·L-1,2 6 0mmol·L-1)胁迫下 ,对毛白杨幼苗的超氧化物歧化酶 (SOD)和过氧化物酶 (POD)活性以及丙二醛 (MDA)含量进行测定 .结果发现 ,在NaCl胁迫 3小时后 ,幼苗SOD和POD活性显著降低 ,随着胁迫时间的延长 ,这两种酶活性降低较缓慢 ,但SOD活性下降程度均较POD小 .在NaCl胁迫中 ,MDA含量明显增加 ,并于胁迫 15小时后达到最大值 ,随后含量增加较小 .进一步分析发现 ,不同浓度NaCl处理对SOD和POD活性以及MDA含量的作用效应是不同的 ,其中 2 6 0mmol·L-1NaCl处理明显促进幼苗SOD和POD活性的下降与MDA含量的增加 ;而且MDA含量与SOD和POD活性的下降有关 .结果表明 ,NaCl胁迫所引起的SOD和POD活性下降可能加强膜脂过氧化作用 ,最终导致幼苗MDA含量的增加与伤害的发生更多还原

【Abstract】 To explore the antioxidant defense system of Populus tomentosa cuttings subjected to salt stress, the cuttings were treated with three different concentrations (85?mmol·L -1 , 170?mmol·L -1 , 260?mmol·L -1 ) of NaCl for 3\|54?h, and the changes in superoxide dismutase (SOD) and peroxidase (POD) activities, and malondialdehyde (MDA) content in the leaves of cuttings were investigated. The results showed that SOD and POD activities significantly decreased during 3?h at the beginning of all NaCl treatment, and then slightly decreased during a period of 9\|54?h, but a lower decrease in SOD activity than in POD activity was observed in all treated cuttings. MDA content distinctly increased and reached a maximum value during 15?h after the beginning of salt stress, and then decreased, but its level was higher than the control. The decreased SOD and POD activities and the increased MDA content affected by the treatment of 260?mmol·L -1 NaCl were more obvious than that affected by the treatment of 85?mmol·L -1 or 170?mmol·L -1 NaCl. It is possible that the decrease in SOD and POD activities under salt stress resulted in the enhancement of membrane lipid peroxidation, which seems to be the key factor that leads to the increase of MDA content and the occurrence of oxidative damage to cuttings.更多还原