渗透胁迫对玉米幼苗叶片不同形态多胺含量的影响

用高压液相色谱法，研究了玉米品种农大108（抗旱性较强）和掖单13（抗旱性较弱）幼苗叶片中游离态(free, f)、酸可溶性共价结合态(AS-conjugated)和酸不溶性共价结合态(AIS-bound) 多胺（polyamine, PA）与渗透胁迫的关系。结果发现，渗透胁迫7 d，农大108的fSpd和fSpm的含量显著(P＜0.05)上升，而掖单13的fPut的升幅显著(P＜0.05)。用S-腺苷蛋氨酸脱羧酶（SAMDC）抑制剂甲基乙二醛-双（鸟嘌呤腙）（MGBG）处理农大108，显著抑制了渗透胁迫诱导的fSpd和fSpm的增加，并且加重了渗透胁迫伤害，用外源Spd处理掖单13，则显著促进了渗透胁迫诱导的fSpd和fSpm的增加，并且减缓了渗透胁迫的伤害。渗透胁迫下，农大108幼苗叶片中AS-conjugated-PA和AIS-bound-PA的上升幅度都显著大于掖单13。用转谷氨酰胺酶（TGase）抑制剂菲咯啉(o-Phen)处理，则抑制了渗透胁迫诱导的AIS-bound-PA含量的上升，并加重了渗透胁迫的伤害。上述结果说明，玉米幼苗叶片中的fSpd、fSpm、AS-conjugated-PA和AIS-bound-PA的升高有利于增强幼苗的抗渗透性。

Effect of Osmotic Stress on the Contents of Different Form Polyamines in Leaves of Maize Seedlings

The changes in contents and forms of polyamines(PAs) in seedling leaves of two maize(Zea mays L.) cultivars,Nongda 108(drought-tolerant) and Yedan 13(drought-sensitive),were investigated under osmotic stress.On the 8~(th) day after polyethylene glycol(PEG)-6 000 treatment,free spermidine(fSpd) and free spermine(fSpm) content in leaves increased significantly(P<0.05)in Nongda 108,while Yedan 13 showed a significant increase of free putrescine(fPut) content.Thus Nongda 108 gave a higher ratio of(fSpd + fSpm)/fPut than Yedan 13 in leaves under osmotic stress.Exogenous methylglyoxal-bis(guanylhydrazone)(MGBG),which is an S-adenosylmethionine decarboxylase(SAMDC) inhibitor,resulted in reduction of fSpd and fSpm contents and aggravation of PEG-induced injury to Nongda 108 leaves,while exogenous Spd treatment resulted in an increase of fSpd + fSpm in leaves,in concert with an alleviation of PEG-induced injury to seedlings of Yedan 13.Osmotic stress induced significant increases of acid soluble conjugated PA(AS-conjugated PA) and acid insoluble bound PA(AIS-bound PA) contents in leaves of Nongda 108,and osmotic stress affected slightly in Yedan 13 leaves.Exogenous phenanthrolin(o-Phen),an inhibitor of transglutaminase(TGase), aggravated PEG-induced injury to Nongda 108,coupled with decreases of AIS-bound PA content.The results suggest that fSpd,fSpm,AS-conjugated-PA and AIS-bound PA facilitate the osmotic stress tolerance of maize seedlings.