ThERF1 regulates its target genes via binding to a novel cis-acting element in response to salt stress

Ethylene responsive factors (ERFs) are plant-specific transcription factors that are involved in a variety of biological processes. We previously demonstrated that an ERF gene from Tamarix hispida, ThERF1, encodes a protein binding to GCC-box and DRE motifs and negatively modulates abiotic stress tolerance. In the present study, microarray analysis was performed to study the genes regulated by ThERF1 on a genomic scale. There were 154 and 307 genes (respectively representing 134 and 260 unique genes) significantly up- and downregulated by ThERF1 under salt stress conditions, respectively. A novel motif, named TTG, was identified to be recognized by ThERF1, which commonly presents in the promoters of ThERF1-targeted genes. The TTG motif is also bound by other ERFs of a different subfamily from T. hispida and Arabidopsis, indicating that it is commonly recognized by ERF proteins. The binding affinities of ERFs to the TTG motif are significantly induced by salt stress. The TTG motif is more enriched than the GCC-box and DRE motifs in the promoters of ThERF1-targeted genes. Taken together, these studies suggested that the TTG motif plays an important role in the gene expression regulated by ERFs in response to salt stress.