外源NO对Ca（NO3）2胁迫下番茄叶片活性氧损伤的缓解效应

Alleviating Effects of Exogenous Nitric Oxide on Oxidative Damage in Tomato Seedling Leaves under Ca（NO3）2 Stress

为探讨外源一氧化氮(NO)对次生盐渍胁迫下植物抗氧化系统的调节作用,以番茄品种‘秦丰保冠’为试材,在营养液栽培条件下研究叶面喷施外源NO供体硝普钠(SNP)对80mmol·L^-1Ca(NO3)2胁迫下番茄幼苗生长、叶片光合、活性氧物质、抗氧化酶活性和抗坏血酸-谷胱甘肽(AsA-GSH)循环的影响。结果表明,Ca(NO3)2胁迫下喷施SNP处理的番茄幼苗叶片超氧阴离子(O2.-)的产生速率以及过氧化氢(H2O2)、丙二醛(MDA)、脱氢抗坏血酸(DHA)、氧化型谷胱甘肽(GSSG)的含量和电解质渗漏率显著降低,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、脱氢抗坏血酸还原酶(DHAR)和单脱氢抗坏血酸还原酶(MDHAR)的活性显著升高或得以维持,同时叶片抗坏血酸(AsA)、谷胱甘肽(GSH)含量及其还原力(AsA/DHA、GSH/GSSG值)显著升高,叶片活性氧损伤得到有效缓解,叶绿素降解和光合速率的下降得到有效抑制,进而促进了植株的生长发育,提高了番茄幼苗的耐盐能力。

【Objective】 In relatively enclosed greenhouses, soil salts tend to accumulate gradually in topsoil duo to the special greenhouse environment of no rain water leaching, high temperature and resultant high evaporation, thus leading to serious secondary salinization of the greenhouse soil. According to relevant reports, the high level of Ca(NO3)2 accumulation was one of the main causes of high soil salinity in greenhouses. Nitric oxide (NO) is a kind of micromolecule active material that generally exists inside plants. As a plant hormone and signaling molecule, NO extensively participates in regulating of plants’ responses to various adversity stress. The aim of this paper is to investigate roles of exogenous NO in regulating the antioxidant system of plants under Ca(NO3)2 stress.【Method】A hydroponic experiment was conducted to investigate effects of foliar spray of sodium nitroprusside (SNP) as exogenous NO donor on growth of tomato (‘Qin Feng Bao Guan’) seedlings, and photosynthetic, reactive oxygen, anti-oxidase activities, and ascorbate-glutathione cycle in their leaves under the stress of 80 mmol·L^-1 Ca(NO3)2.【Result】In the leaves of the tomato seedlings under Ca(NO3)2 stress, foliar spray SNP significantly lowered O2·- production rate, H2O2, malondialdehyde, dehydroascorbic acid and oxidized glutathione in content and electrolyte leakage rate, but heightened or maintained superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase and monodehydroascorbate reductase in activity;besides, it significantly increased the contents of ascorbic acid and glutathione and their reducing power. As a result, active oxygen damage of the leaves was effectively alleviated, and chlorophyll degradation and photosynthetic rate declining trend were effectively suppressed.【Conclusion】 Exogenous NO treatment plays an important role in maintaining or improving the activity of antioxidant enzymes and promoting the operation of aseorbate-glutathione (AsA-GSH) cycle in tomato under the stress of Ca(NO3)2, thus relieving the plants of oxidative damage significantly, and improving their leaf membrane system in stability, their photosynthetic function, their tolerance to salt and eventually their growth.