NaCl胁迫下胡杨(Populus euphratica)和群众杨(P.popularis)抗氧化能力及耐盐性

Genotypic differences between Populus euphratica and P.popularis in antioxidative ability and salt tolerance under NaCl stress

在盐浓度逐渐提高的胁迫条件下，对抗盐的胡杨（Populuseuphratica）和盐敏感的群众杨（Ppopularis35-44）1年实生苗木叶片中Na^＋、Cl^-水平、O2^-产生速率以及抗氧化酶：超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、过氧化氢酶（CAT）和谷胱甘肽还原酶（GR）的动态变化以及抗盐性进行了研究。结果表明，在盐浓度不断提高的胁迫条件下，群众杨叶片中Na^＋、Cl^-浓度持续增加，盐胁迫18d时，群众杨叶中Na^＋、Cl^-含量分别达到对照的17．8和14．6倍，此时O2^-产生速率也达到最高水平。而在盐胁迫期间，群众杨叶片SOD活性没有明显提高，CAT活性维持在对照水平以下，只有APX和GR活性在盐胁迫13—18d，即盐害症状出现前才有所上升，属于典型的盐害反应。胡杨与群众杨明显不同：在盐胁迫初期，胡杨叶片Na^＋、Cl^-含量虽然没有明显的变化，但胡杨叶片中O2^-产生速率在盐胁7d时明显提高，SOD、APX、CAT活性也都先后相应上升，表明胡杨能响应盐胁迫并上调SOD、APX和CAT等保护酶类，降低盐诱导的膜脂过氧化，从而减少了电解质外渗，最终提高了树木的抗盐性。

In the present study, we investigated the effects of increasing soil NaC1 on leaf Na^＋ and Cl^- concentrations,O2^- production rate, activity of antioxidant enzymes, e.g. superoxide dismutase （SOD）, ascorbate peroxidase （APX）, catalase （CAT） and glutathione reductase （GR） and the relevance to salt tolerance in 1-year-old plants of Populus euphratica （salt-resistant） and P. popularis 35 -- 44 （salt-sensitive）. Na^＋ and Cl^- concentrations in P. popularis leaves markedly increased upon increasing salinity and reached the highest level on day 18, which was 17.8- and 14.6-fold of that in controls, correspondingly, O2^- production rate in P. popularis leaves increased to the maximum. However, there was no significant increase of SOD activity in stressed P. popularis plants and CAT activity remained lower than control levels during the period of salt stress. APX and GR activity began to increase after 13 -- 18 days of salt treatment when stressed P. popularis plants exhibited leaf injury symptoms. This was the typical response of salt-induced oxidative stress in P. popularis. In contrast to P. popularis, Na^＋ and Cl^- concentration in P. euphratica leaves did not increase after salt stress was initiated, but O2^- production rate began to increase after 7 days of salinity. Activity of SOD, APX and CAT was elevated corresponding to the increased O2^- production, suggesting that P. euphratica plants were able to sense salt stress and up-regulated the antioxidant enzymes to reduce salt-induced lipid peroxidation and membrane permeability, which contributing to membrane integrity maintenance and salt tolerance in P. euphratica.