The Antioxidative Function Of Glutaredoxin Gene OsGRX20 In Rice

GRXs are small glutathione dependent oxidoreductases, which play an important role during plants growth and in defense against various stresses. CPYC-, CGFS-, CC-are three types of GRXs in plants which are clarified by their amino acids at active site. Only a few rice CPYC-type GRXs have been studied. OsGRX20 belongs to CYPC type. In our previous study, a protein OsGRX20 was isolated by two-dimensional electrophoresis, which was upregulated after inoculated with bacterial blight strain Zhe173. Then, over-expression vector and RNAi vector were constructed, and transgenic rice lines were obtained. In this study, the function of OsGRX20 was studied. The results were as follows:(1) Under methyl viologen (MV) treatment, the stems of Yongjing 50A exhibited milder symptoms and its relative dry weight was higher than Xiushui 11. The relative expression of OsGRX20 in the Yongjing 50A was significantly upregulated relative to Xiushui 11 under MV and 45℃ treatment. These results showed that OsGRX20 is related with the tolerance to oxidative stresses of Yongjing 50A.(2) After treatment with 10μM MV, the relative fresh weight and relative chlorophyll content of OsGRX20 over-expression lines (OE) were higher than wide type (WT), whereas those of RNAi lines (SE) were lower than WT. When the seedlings were treated with MV for 24h, the OE lines showed lower O2 accumulation, compared to WT. This suggested that OsGRX20 can enhance the tolerance to oxidative stress.(3) In order to understand the antioxidative mechanism of OsGRX20, we analyzed the expression of oxidative related genes. The expression of OsSodB, OsAPXl, and OsCatC in OE lines was up-regulated under MV treatment. The results indicated that the OsGRX20 may affect the expression of OsSodB, OsAPXl and OsCatC genes to improve rice tolerance to oxidative stress.(4) To investigate the subcellular localization of OsGRX20 in plant cells, the OsGRX20 was fused with GFP and the construct was transiently expressed in Nicotiana benthamiana leaf and monitored by capturing GFP fluorescence. Our results suggested that OsGRX20 proteins were localized in both nucleus and cytoplasm.