连续2年土壤砷胁迫对三七(Panax notoginseng)细胞膜透性和抗氧化酶活性的影响

通过盆栽试验和室内分析相结合的方法，研究不同砷处理（As5+：0、20、80、140、200和260mg/kg，采用Na3AsO4配制）对三七营养生长期叶片中的细胞膜透性、丙二醛（MDA）含量和抗氧化酶[超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和多酚氧化酶（PPO）]活性的影响，探讨三七细胞膜透性和抗氧化系统酶活性对砷胁迫的响应。结果表明：（1）随着砷质量分数的增加，叶片细胞膜透性和MDA含量逐渐升高；连续2年砷处理为260mg/kg时，细胞膜透性和MDA含量分别比对照增加160.5%和48.8%；叶片中丙二醛含量与砷质量分数呈极显著正相关关系；（2）第1年砷胁迫，SOD和PPO活性维持稳定，POD活性有所降低；连续2年砷胁迫，SOD活性随着砷质量分数的增加呈现先升高后降低的趋势，且砷处理为260mg/kg时，酶活性仅为对照的35.7%；POD和PPO活性随砷质量分数的增加而降低；2年砷胁迫CAT活性均随着砷质量分数的增加而增加。总之，在砷胁迫条件下，三七叶片细胞膜受到严重伤害，抗氧化酶系统中POD和PPO活性受到抑制，SOD和CAT是三七叶片中清除过氧化作用的关键酶，连续2年砷胁迫对三七叶片的影响具有一定的累积效应。

Effects of Soil As on Cell Membrane Permeability and Antioxidant Enzymes Activities of Panax notoginseng

Pot experiments were conducted in order to understand effects of arsenic (As) (As5+:0, 20, 80, 140, 200, 260mg/kg) on cell membrane permeability, malondialdehyde content (MDA) and antioxidases[superoxide dismutase (SOD), perosidase (POD), catalase (CAT) and polyphenol oxidase (PPO)] of P. notoginseng at growing stage and apply theory and practice basis for resistance of P. notoginseng to As stress. The results showed that:(1) Cell membrane permeability and MDA content of leaves of P. notoginseng increased with the increase of As mass fractions. Cell membrane permeability and MDA content increased by 160.5% and 48.8% under two-year consecutive 260mg/kg As treatment, respectively. Positive relationship between MDA content and As treatment was observed. (2) Activities of SOD and PPO kept stable and activity of POD decreased under the first year As stress. SOD activity of leaves of P. notoginseng increased and then decreased with the increase of As mass fraction two-year consecutive As stress. SOD activity decreased by 35.7% under 260mg/kg As treatment comparing with control. POD and PPO activities decreased with the increase of As mass fraction. CAT activity increased with increase in As treatment concentrations at the first year and two-year consecutive As stress. In general, the results indicate that cell membrane of leaves of P. notoginseng was damaged under As stress with protein and sugar metabolisms produced anti-stress effects to some extent, POD and PPO activities inhibited and SOD and CAT acted as key enzymes to eliminate peroxidation. There are accumulating effects of two-year consecutive As stress on leaves of P. notoginseng.