The changes in levels and forms of polyamine(PA) in the coleoptiles of two wheat (Triticum aestivum L.) cultivars differing in drought tolerance were investi18' showed marked increases in free spermidine (Spd)and spermine (Spm) levels in coleoptiles after being treated with polyethylene glycol (PEG)-6000 for 2 d in significant increase in free putrescine (Put) content.Treatment of coleoptiles with methylglyoxal-bis(guanylhydrazone) (MGBG), an S-adenosylmethionine decarboxylase (S-AMDC) inhibitor, resulted in reduction of free Spd and free Spm levels in coleoptiles and coleoptile, while exogenous Spd treatment resulted in an increase in free Spd + free Spm content of coleoptiles,9' coleoptile. Osmotic stress induced significant increases in perchloric acid-soluble conjugated PA (PS conjugated PA) and perchloric acid-insoluble conjugated 18', whereas osmotic stress affected only slightly the PS9' coleoptiles. Treatment of coleoptiles with phenanthroline (o-Phen), an inhibitor of transglutaminase(TGase), also aggravated the PEG-induced injury toin the level of PIS-conjugated PA. These results suggest that free Spd, free Spm and conjugated PA enhance the osmotic stress tolerance of wheat coleoptiles.%用高压液相色谱法研究了豫麦18(抗旱性较强)和扬麦9号(抗旱性较弱)小麦胚芽鞘中三种不同形态的多胺(polyamine,PA):游离态多胺(PA)、高氯酸可溶性结合态多胺(PS结合态PA)和高氯酸不溶性结合态多胺(PIS结合态PA)与渗透胁迫的关系.结果发现:渗透胁迫2 d,豫麦18胚芽鞘中的游离态Spd和游离态Spm的含量明显上升,而扬麦9号的游离态Put的上升明显.S-腺苷蛋氨酸脱羧酶(S-AMDC)的抑制剂--甲基乙二醛-双(鸟嘌呤腙)(MGBG)处理豫麦18,明显抑制了渗透胁迫诱导的游离态Spd和游离态Spm的增加,并且加重了渗透胁迫伤害,外源Spd处理扬麦9号明显促进了渗透胁迫诱导的游离态Spd和游离态Spm的增加,并且减缓了渗透胁迫的伤害.渗透胁迫下,豫麦18胚芽鞘中的PS结合态PA和PIS结合态PA的上升幅度都明显大于扬麦9号.菲咯啉(o-Phen)抑制渗透胁迫下PIS结合态PA的合成并加重了渗透胁迫对胚芽鞘的伤害.这些结果表明:小麦胚芽鞘中的游离态Spd、游离态Spm、PS结合态PA和PIS结合态PA的升高有利于增强渗透胁迫抗性.
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