The cotton dehydration-responsive element binding protein GhDBP1 contains an EAR-motif and is involved in the defense response of Arabidopsis to salinity stress

Abstract

Our previous work reported that cotton dehydration-responsive element (DRE) binding protein 1 (GhDBP1) could function as an active transcriptional repressor for DRE-mediated gene expression. However, the repression mechanism utilised by GhDBP1 was unclear. In this report, we demonstrate that GhDBP1’s transcriptional repression domain is located at the C-terminus, and is known as an ERF-associated amphiphilic repression (EAR)-motif. Furthermore, the amino acid residues aspartic acid (D), leucine (L), asparagine (N) and proline (P) are conserved in the EAR-motif, and were found to be necessary for repression through mutational analysis. In addition, our promoter assays demonstrated a dehydration-induced and rehydration-repressed expression pattern of GhDBP1. Transgenic Arabidopsis plants overexpressing GhDBP1 were more sensitive to high salinity stress and appeared to downregulate the expression levels of the stress-induced effecter genes. Taken together, our findings provide an important insight into GhDBP1’s potential molecular repression mechanism and how it is involved in plant stress responses.