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

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

以黄瓜为材料,研究了外源硅(K2SiO31.0mmol/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。

With K2SiO4 （1.0 mmol/L） treatment, the effects of Si on the distribution of Na^＋, K^＋ to chloroplasts and antioxidant system of cucumber leaves under 50 mmol/L NaCl stress were studied. The results showed that there was a selective transport of K^＋ into the chloroplasts so that Na^＋ content of chloroplasts was lower under Si treatment （Table 1）; H2O2 and MDA contents in chloroplasts were significantly decreased （Fig. 1）, and the activities of SOD, APX, GR and DHAR were increased simultaneity （Fig.2）, and AsA, GSH contents were also increased in chloroplasts of salt-stressed cucumber by additional Si treatment （Fig.3）. It may be concluded that Si could decrease absorption of Na^＋ and increase ability of active oxygen scavenging in chloroplasts, therefore the injury of chloroplast membrane under salinity stress in cucumber was alleviated.