Abstract: Ethylene responsive factors (ERFs) are important plant-specific transcription factors. Some of them have been identified to interact with the ethylene-responsive GCC box and the dehydration responsive element (DRE). They usually play very important regulatory roles in response to biotic and abiotic stresses in plants. In our study, an ERF gene W6 was isolated from wheat (Xiao baimai) cDNA library, which belongs to ERF IV subfamily. Full-length W6 cDNA encoded an ERF protein containing a conserved ERF DNA-binding motif, two putative nuclear localization sequences and a C-terminal acidic transcription activation domain. W6 expression in wheat can be induced by various treatments such as cold, drought, salt, ABA and fungal pathogens. We constructed transgenic vector (35S::pBI121::W6) containing CaMV 35S promoter and then obtained W6-overexpresed tobacco plants by Agrobacterium-mediated transformation in order to identify the function of W6. Under the treatment with 200 mmol L^-1 NaCl for 50 d, the transgenic plants grew well but the control plants nearly died. The root length of transgenic tobacco plants was between 1.40 cm and 3.93 cm, while that of the control only 0.20 cm. The root weight of transgenic tobacco plants was between 2.41 g and 7.79 g, while that of the control only 0.06 g. SOD activity and chlorophyll content in transgenic plants increased markedly compared to the control. All results the above showed that the overexpression of W6 improved tobacco’s salt tolerance, and W6 may act as a connector among different signal transduction pathways. The overexpression of W6 activated the expression of GCC box-containing genes PR2, PR3, PR5, and DRE/CRT genes NtERD10A and NtERD10C under normal growth conditions, and the tolerance to salt stress was improved in transgenic tobacco plants, which suggested that W6 regulates osmotic tolerance by activation of downstream gene expression through interaction with the GCC box or DRE.

Key words: ERF, Transgenic plants, Salt tolerance, Tobacco