Overexpression of a Camellia sinensis DREB transcription factor gene (CsDREB) increases salt and drought tolerance in transgenic Arabidopsis thaliana

Dehydration-responsive element-binding protein (DREB) transcription factors play key roles in plant stress signal transduction pathways. We herein describe the functions of a Camellia sinensis DREB transcription factor (CsDREB) in response to abiotic stress. Subcellular localization analyses indicated that the CsDREB localizes to the nucleus. CsDREB expression in C. sinensis leaves was induced by heat, cold, drought, high salinity, H2O2, and exogenous abscisic acid (ABA). Additionally, CsDREB showed no transcriptional activation in Saccharomyces cerevisiae. Transgenic Arabidopsis thaliana plants overexpressing CsDREB exhibited enhanced tolerance to salt and drought stresses. The overexpression of CsDREB in A. thaliana plants resulted in the up-regulated expression of ABA-dependent stress-induced genes (i.e., AtRD29B, AtRAB18, AtABI1, and AtABI2) and ABAindependent stress-induced genes (i.e., AtCOR15a and AtRD29A). Furthermore, an analysis of the CsDREB promoter sequence revealed the presence of several abiotic and biotic stress-related motifs, along with the developmental stageand tissue-specific elements. An examination of the transient expression of the CsDREB promoter in Nicotiana benthamiana leaves revealed that the promoter is highly responsive to ABA and methyl jasmonate. Collectively, these results suggest that CsDREB may increase plant tolerance to salt and drought stresses via both ABA-dependent and ABAindependent pathways.