氧化胁迫对水稻幼苗抗冷力的影响

EFFECT OF OXIDATIVE STRESS ON COLD TOLERANCE IN RICE SEEDLINGS

利用Ｈ２Ｏ２和甲基紫精（ＭＶ）对水稻幼苗作三种不同程度的氧化胁迫预处理。结果表明：轻度氧化胁迫预处理（１０ｕｍｏｌ／ＬＨ２Ｏ２或１０ｕｍｏｌ／ＬＭＶ处理４ｈ）提高了水稻幼苗的抗冷力，严重氧化胁迫预处理（１０ｕｍｏｌ／ＬＨ２Ｏ２或１０ｕｍｏｌ／ＬＭＶ分别处理１６ｈ和４０ｈ）则削弱水稻幼苗的抗冷力。氧化胁迫预处理刺激了水稻幼苗叶片抗氧化酶（ＳＯＤ，ＣＡＴ，ＰＯＸ和ＡＰＸ）的活性。经冷胁迫后，不同预处理苗的叶片抗氧化酶活性、膜脂过氧化和膜结构的变化趋势不同：轻度氧化胁迫预处理使幼苗仍保持较高的抗氧化酶活性，减轻了由冷胁迫引起的膜脂过氧化和细胞膜的渗漏程度，而严重氧化胁迫预处理则相反。因此，水稻幼苗对氧化胁迫感知并作出反应的机制（氧化应激机制）在水稻幼苗对低温反应和适应过程中起着很重要的调节作用。

Effects of different extents of oxidative stress caused by 10 umol/L H2O2 or10 umol/L methyl viologen (MV) on cold tolerance of rice seedlings were studied. Theresults showed that mild oxidative stress (10 umol/L H2O2 or 10 umol/L MV for 4 h)could induce cold tolerance, while severe oxidative stress might aggravated chilling injuryon rice seedlings. The antioxidatase (POX, SOD, CAT andf APX) activities in leaves fromvarious pretreated seedlings were all increased. After chilling stress, the changes inantioxidatase aCtivities, electrolyte leakage and MDA content among different pretreatedseedlings were different. Mild oxidative stress could sustain high level of antioxidataseactivities, reduce the increase of membrane lipid peroxidation and cellular electrolyte leakageinduced by chilling stress, but contrary effect was observed by severe oxidativepretreatment. It is suggested that the mechanism of rice seedlings responsing to oxidativestress (cellular oxidative stress response) might be the important regulatory mechanism forrice seedlings during chilling stress or cold tolerance.