ABSTRACT
Proteins arc 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 pcroxidase (PHGPx) is a unique antioxidant enzyme that directly reduces lipid hydroperoxides in biomembranes and plays a vital role in defense against mernhrane 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 NaCI, but weakly influenced by several plant hormones. Time- and dose-dependent effects were observed in both H2O2 and NaCI 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 NaCI for 24 h. Additionally, dimethylthiourea, a H2O2 trap, inhibited H2O2-enhanced expression of OsPHGPx, but did not impair the enhanced effect of NaCI, 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.