中文摘要：

为探讨一氧化氮（nitric oxide, NO）对紫外线-B（UV-B）辐射胁迫下植物抗氧化系统的影响，以盆栽5年生南方红豆杉（Taxus chinensis var. mairei）幼苗为材料，硝普钠（sodium nitroprusside, SNP）为外源NO供体，设置CK（对照）、SNP（＋0.1 mmol·L-1 SNP）、UV-B（＋4.22 kJ·m-2·d-1 UV-B）及UV-B＋SNP（＋0.1 mmol·L-1 SNP ＋ 4.22 kJ·m-2· d-1UV-B）4个处理，研究外源NO对UV-B胁迫下南方红豆杉幼苗针叶过氧化氢（H2O2）含量、脂质过氧化程度及抗氧化物质含量的影响。结果表明：UV-B胁迫显著提高了南方红豆杉针叶H2O2及MDA含量（P〈0.05），施加外源NO降低UV-B胁迫下针叶H2O2及MDA含量，提高紫杉醇、类黄酮及类胡萝卜素等抗氧化物质含量（P〈0.05）；各处理对抗氧化酶活性影响不同，SNP处理显著提高针叶中CAT和POD活性（P〈0.05），UV-B和SNP＋UV-B处理均提高针叶中POD活性，降低CAT活性和APX活性（P〈0.05）。本研究证实，外源NO可提高UV-B胁迫下植物抗氧化酶活性和抗氧化物质含量，降低其H2O2含量及脂质过氧化程度，从而在一定程度上缓解UV-B胁迫对植物的伤害。

英文摘要：

In order to approach the effect of nitric oxide （NO） on the plant antioxidant system under the stress of UV-B radiation, a pot experiment with 5-year old Taxus chinensis var. mairei seedlings was conducted to study the effect of sodium nitroprusside （SNP） as an exogenous NO donor on the seedlings leaf antioxidant system under elevated UV-B radiation. Four treatments, i.e., CK （control）, SNP （＋ 0.1 mmol·L-1 of SNP）, UV-B （＋4.22 kJ·m-2·d-1 UV-B）, and UV-B＋SNP （＋ 0.1 mmol·L-1 of SNP ＋ 4.22 kJ·m-2·d-1 UV-B）, were installed, and the leaf hydrogen peroxide （H2O2）, malondialdehyde （MDA）, and antioxidant concentrations were measured. Elevated UV-B radiation increased the leaf H2O2 and MDA concentrations significantly （P〈0.05）, while exogenous NO addition decreased the H2O2 and MDA concentrations and increased the taxol, flavonoids, carotenoids and soluble protein concentrations significantly （P〈0.05）. Different treatments had different effects on the leaf antioxidase activities. SNP increased the CAT and POD activities significantly （P〈0.05）, while UV-B and SNP＋UV-B increased the POD activity and decreased the CAT and APX activities significantly （P〈0.05）, as compared with CK. It was suggested that exogenous NO could increase the plant antioxidase activities and antioxidant concentrations and decrease the plant H2O2 concentrations and lipid peroxidation, and thereby, could relieve the impact of UV-B stress on plant to a certain extent.