外源硅对盐胁迫下黄瓜幼苗叶绿体活性氧清除系统的影响

以黄瓜为材料，研究了外源硅（K2SiO3 1．0mmol／L）对NaCl（50mmol/L）胁迫下黄瓜幼苗叶绿体中Na^＋、K^＋向叶绿体分配及活性氧清除系统的影响。结果表明：盐胁迫下硅处理使叶绿体在K^＋与Na^＋之间选择性吸收K^＋，从而降低了叶绿体内Na^＋的含量；同时Si处理可以显著降低盐胁迫下叶绿体中过氧化氢（H2O2）和丙二醛（MDA）含量，提高超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、谷胱甘肽还原酶（GR）和脱氢抗坏血酸还原酶（DHAR）的活性及抗坏血酸（ASA）、还原型谷胱甘肽（GSH）含量。说明Si不仅能降低叶绿体对Na^＋的选择吸收，还能增强叶绿体活性氧清除系统清除活性氧的能力，缓解盐胁迫对叶绿体膜的伤害。

Effects of Exogenous Silicon on Active Oxygen Scavenging Systems in Chloroplasts of Cucumber (Cucumis sativus L.) Seedlings under Salt Stress

With K2SiO4 (1.0 mmol/L) treatment,the effects of Si on the distribution of Na+, K+ tochloroplasts and antioxidant system of cucumberleaves under 50 mmol/L NaCl stress were studied.The results showed that there was a selective trans-port of K+ into the chloroplasts so that Na+ contentof chloroplasts was lower under Si treatment (Table1); H2O2 and MDA contents in chloroplasts weresignificantly decreased (Fig.1), and the activitiesof SOD, APX, GR and DHAR were increased si-multaneity (Fig.2), and AsA, GSH contents werealso increased in chloroplasts of salt-stressed cu-cumber by additional Si treatment (Fig.3). It maybe concluded that Si could decrease absorption ofNa+ and increase ability of active oxygen scaveng-ing in chloroplasts, therefore the injury of chloro-plast membrane under salinity stress in cucumberwas alleviated.