在常温下用不同浓度的外源H2O2(0～20 mmol·L-1)预处理水稻幼苗,再进行12 h 6℃低温胁迫,根据幼苗相对含水量和质膜相对透性筛选最佳外源H2O2处理浓度,并分析最佳外源H2O2浓度下幼苗的渗透调节物质和活性氧相关指标的变化.结果表明:(1)0～8 mmol·L-1 H2O2预处理可以增加水稻幼苗的相对含水量,降低其质膜相对透性,并以4 mmol·L-1 H2O2的效果最佳.(2)低温胁迫后,与对照组相比,4 mmol·L-1外源H2O2预处理降低了水稻幼苗萎蔫程度,并使其总呼吸速率、交替途径容量都有增加,同时还抑制了丙二醛的含量,增加了可溶性糖、可溶性蛋白质和脯氨酸的含量.(3)外源H2O2预处理对水稻幼苗的内源H2O2含量以及O(-)/(·)2产生速率没有显著影响.研究发现,外源H2O2可以通过提高呼吸速率、降低脂质过氧化程度、增加碳氮代谢来有效增强水稻幼苗的抗寒性,它可能以一种独立于内源活性氧系统之外的方式发挥作用.
Regulation of Exogenous H2O2 on Rice Seedlings Chilling Tolerance
After 12 h of chilling stress at 6℃,pretreatment with H2O2 0～20 mmol·L-1 as foliar spray under normal growth conditions was measured.The results indicated that 0～8 mmol·L-1 H2O2 could significantly enhance relative water content (RWC) and decrease relative membrane penetration.The obvious effect of H2O2 occurred at 4 mmol·L-1.After chilling stress,compared with water-treated seedlings (contro1),4 mmol·L-1 H2O2 pretreatment relieved the wilting degree,increased total respiration rate (Vt),capacity of alternative pathway (Valt),inhibited the malonaldehyde (MDA) content and increased the soluble sugar content,soluble protein content and proline content.However,pretreatment of rice plants with 4 mmol·L-1 H2O2 showed no obvious effect on endogenous H2O2 content and the generating rate of O(-)/(·)2.These results suggest that the exogenous H2O2 could enhance rice seedlings chilling tolerance by enhancing respiration rate,the metabolism of carbohydrate and nitrogen and decreasing lipid peroxidation.The exogenous H2O2 was independent with the endogenous reactive oxygen species (ROS) pool in a certain way.
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