外源CaCl_(2)对盐胁迫下西伯利亚白刺活性氧代谢的影响

Effects of exogenous CaCl_(2) on reactive oxygen species metabolism in Nitraria sibirica under NaCl stress

土壤盐渍化已成为严峻的世界性问题,严重威胁着农业生产和生态安全。以西伯利亚白刺(Nitraria sibirica)为试材,采用营养液无土栽培方式,研究了外源CaCl_(2)对盐胁迫下西伯利亚白刺幼苗叶片活性氧(ROS)代谢、抗坏血酸-谷胱甘肽(AsA-GSH)循环的影响。结果表明:盐胁迫显著提高了西伯利亚白刺叶片中超氧阴离子(O_(2)ˉ·)产生速率、过氧化氢(H2O_(2))含量以及抗坏血酸过氧化物酶(APX)、单脱氢抗坏血酸还原酶(MDHAR)活性,显著降低了抗坏血酸(AsA)含量和脱氢抗坏血酸还原酶(DHAR)活性。施加CaCl_(2)显著降低了盐胁迫下西伯利亚白刺叶片O_(2)ˉ·产生速率和H2O_(2)含量;显著提高了AsA含量,DHAR、谷胱甘肽还原酶(GR)、APX、MDHAR活性以及AsA/DHA (氧化型抗坏血酸)、GSH (还原型谷胱甘肽)/GSSG (氧化型谷胱甘肽)比值。外源CaCl_(2)通过增加盐胁迫下西伯利亚白刺叶片抗氧化酶活性以及抗氧化物质AsA和GSH含量,增强AsA-GSH循环清除活性氧的能力,缓解盐胁迫对西伯利亚白刺的氧化伤害。

Soil salinization has become a severe problem worldwide,which greatly threatens agricultural production and ecological safety.The effect of exogenous CaCl_(2) on modulating reactive oxygen species (ROS)metabolism and ascorbate–glutathione (AsA-GSH) cycle in NaCl-stressed Nitraria sibirica seedlings was investigated.The results showed that salt stress significantly increased the production rate of superoxide anion (O_(2)ˉ·),as well as hydrogen peroxide (H2O_(2)) content and the activities of ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDHAR) in the leaves of N.sibirica seedlings,while notably reduced AsA content and dehydroascorbate reductase (DHAR) activity.Exogenous CaCl_(2) significantly reduced the production rate of O_(2)ˉ·and H2O_(2) content in the leaves of N.sibirica seedlings under salt stress,while remarkably improved the contents of AsA and GSH,the activities of DHAR,glutathione reductase (GR),APX and MDHAR,and the ratios of ASA/DHA (dehydroascorbate) and GSH (reduced glutathione)/GSSG (oxidized glutathione).The results showed that exogenous CaCl_(2) could improve the ability of AsA-GSH cycle to remove ROS via increasing the activities of antioxidant enzymes and the contents of antioxidant substances,i.e.AsA and GSH,in the leaves of N.sibirica seedlings under salt stress,which alleviated the oxidative damage of salt stress to N.sibirica seedlings.