Expression of eggplant ascorbate peroxidase increases the tolerance of transgenic rice plants to flooding stress

Rice is sensitive to flooding during seed germination and early seedling growth. The objective of this study was to transfer ascorbate peroxidase (APX) cDNA from the eggplant (Solanum melongena, Sm) under the control of an ubiquitin promoter into rice (Oryza sativa) via Agrobacterium-mediated transformation. A real-time polymerase chain reaction analysis demonstrated that SmAPX gene was over-expressed in transgenic rice lines (SmAPXs). APX gene expression profiles were well matched with the data for APX enzyme activities and total chlorophyll contents in the non-transgenic (NT) and transgenic plants. The activity of APX in the transgenic line SmAPX6 was 9-fold higher than in NT plants under waterlog, and the amount of APX in the SmAPX6 line also accumulated greatly according to a Western blot analysis. The over-expression of SmAPX in rice seedlings exhibited stronger resistance to flood tolerance, less oxidative injury, and grew faster than NT plants exposed to flood treatment.