中文摘要：

研究了渗透胁迫下，小麦品种豫麦18（抗旱性较强）和扬麦9号（抗旱性较弱）幼苗叶片中亚精胺（Spd）和抗氧化非酶物质含量的变化．渗透胁迫2d，抗旱性弱的扬麦9号小麦幼苗叶片的过氧化氢（H2O2）和丙二醛（MDA）含量的上升幅度明显大于抗旱性强的豫麦18，而豫麦18幼苗叶片Spd、抗坏血酸（ASA）和谷胱甘肽（GSH）含量的上升幅度明显大于扬麦9号．胁迫条件下，外源Spd处理扬麦9号，不仅明显提高其幼苗叶片的Spd含量，而且AsA和GSH含量也明显提高，而其H2O2和MDA则明显下降；Spd的生物合成专一性抑制剂——甲基乙二醛一双（鸟嘌呤腙）（MGBG）处理豫麦18，则明显抑制其在渗透胁迫下叶片中Spd，ASA和GSH含量的上升，而明显促进其H2O2和MDA含量的上升．这些结果表明，渗透胁迫下小麦幼苗叶片中的Spd减轻活性氧对幼苗伤害的原因之一，可能是通过提高ASA和GSH等抗氧化非酶物质含量而降低活性氧水平．

英文摘要：

The changes in contents of spermidine （Spd） and antioxidation non-enzyme substances were investigated in seedling leaves of two wheat （Triticum aestivum L. ） cultivars, Yumai 18 （drought-tolerant） and Yangmai 9 （drought-sensitive） under osmotic stress. On the 2th day, after polyethylene glycol （PEG） - 6,000 treatment, MDA and H2O2 contents increased more significantly in leaves of Yangmai 9 than in Yumai 18, while Yumai 18 showed a more significant increase in contents of Spd, ASA and GSH. Under osmotic stress, exogenous Spd treatment resulted in the increases not only in Spd content, but also in ASA and GSH, in concert with an inhibition of MDA and H2 O2 contents in seedling leaves of Yangmai 9. Exogenous methylglyoxal-bis （guanylhydrazone） （MGBG）, which is an inhibitor of Spd biosynthesis, resulted in the reduction of Spd, ASA and GSH contents, and resulted in the increase of MDA and H2O2 contents in seedling leaves of Yumai 18 subjected to osmotic stress. The results suggested that osmoinduced increased Spd alleviate the osmoinduced reactive oxygen injury to seedlings via increasing ASA and GSH contents and reducing MDA and H2O2 contents in the leaves.