Functional analyses of ethylene response factor JERF3 with the aim of improving tolerance to drought and osmotic stress in transgenic rice

Ethylene response factor (ERF) proteins play important roles in regulating plant stress response and development. Our previous studies have shown that JERF3 activates the expression of oxidative stress responsive genes in transgenic tobacco and enhances tolerance to salt, drought, and freezing, indicating that JERF3 is a very important transcriptional regulator in dicot plants. In the study reported here, we further addressed the regulatory function of JERF3 in a monocot, rice, by generating transgenic rice plants overexpressing JERF3 and comparing these with non-transgenic rice plants for physiological and molecular alterations and tolerance to drought and osmotic stresses. Growth and development under normal growth conditions were the same in both the transgenic and non-transgenic rice. Interestingly, the JERF3 transgenic plants exhibited better stress tolerance, whereas the non-transgenic rice seedlings showed serious stress symptoms and ultimately died after the drought and osmotic treatments. Biochemical analysis revealed that the contents of soluble sugars and proline were significantly increased in transgenic rice compared with non-transgenic plants under dehydration conditions. In addition, overexpression of JERF3 in rice led to the up-regulated expression of two OsP5CS genes in response to drought treatment compared with their expression in non-transgenic plants. JERF3 also activated the expression of stress-responsive genes, including WCOR413-like, OsEnol, and OsSPDS2, in transgenic rice under normal growth conditions. These data suggest that JERF3 plays important roles in transgenic rice and that it is likely to be beneficial in engineering crop plants with improved tolerance to drought and osmotic stresses.