水稻磷脂氢谷胱甘肽过氧化物酶在蛋白质水平上的组织和诱导表达特征

蛋白质是生命活动的主要承担分子，了解蛋白质在有机体中的时空分布对于正确解析蛋白质的功能十分重要．磷脂氢谷胱甘肽过氧化物酶 (PHGPx) 是目前发现的唯一能够直接还原膜上脂类过氧化物的抗氧化酶，在保护生物膜免受过氧化损伤方面有着重要作用．采用Western blot技术，分析了水稻PHGPx (OsPHGPx) 在水稻不同组织以及多种胁迫条件下的蛋白质表达特征．结果表明，OsPHGPx在成熟水稻植株内主要分布于叶组织中，以旗叶中含量最高，而在水稻幼苗中则在茎及叶组织中均检测到较强的杂交信号．OsPHGPx在幼苗中的表达受到H₂O₂和NaCl的强烈诱导，但植物激素对其表达的影响较弱．H₂O₂和NaCl的诱导效果呈现出时间及剂量的相关性，当用0.5 mmol/L H₂O₂处理12 h或用500 mmol/L NaCl处理24 h，此时OsPHGPx表达量达到最大值．对H₂O₂清除剂二甲基硫脲处理的水稻幼苗，外源H₂O₂的再处理并不能诱导OsPHGPx的表达，而NaCl的诱导效果并不受影响，说明H₂O₂可能并不介导NaCl诱导OsPHGPx的表达．这些结果为进一步研究OsPHGPx在水稻中生物学功能奠定了基础．

Tissue and Induction Expression Profiles of Rice Phospholipid Hydroperoxide Glutathione Peroxidase at Protein Level

Proteins are the major molecules performing life activities, and their spatial and temporal expression profiles in organisms are very important for understanding their accurate functions. Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is a unique antioxidant enzyme that directly reduces lipid hydroperoxides in biomembranes and plays a vital role in defense against membrane peroxidation damage. The protein expression profiles of rice PHGPx (OsPHGPx) were investigated in different rice tissues and under various stress treatments by using Western blot analysis. The results showed that in mature rice plants, OsPHGPx was mainly distributed in leaves, especially flag leaves, and in rice seedlings, OsPHGPx was detected in shoots and leaves. Moreover, OsPHGPx expression in rice seedlings could be markedly induced by H₂O₂ and NaCl, but weakly influenced by several plant hormones. Time- and dose-dependent effects were observed in both H₂O₂ and NaCl treatments, and the strongest induction was observed when rice seedlings were treated with 0.5 mmol/L H₂O₂ for 12 h or 500 mmol/L NaCl for 24 h. Additionally, dimethylthiourea, a H₂O₂ trap, inhibited H₂O₂-enhanced expression of OsPHGPx, but did not impair the enhanced effect of NaCl, implying that NaCl-induced OsPHGPx expression was not mediated by H₂O₂. These results will contribute greatly to further study the exact physiological function of OsPHGPx in rice.