Improvement of drought and salt tolerance in Arabidopsis and Lotus corniculatus by overexpression of a novel DREB transcription factor from Populus euphratica.

A novel DREB (dehydration-responsive element binding) gene, designated PeDREB2a, was isolated from the desert-grown tree, Populus euphratica Oliv. PeDREB2a is classified into the A-5 group of DREB subfamily based on multiple sequence alignment and phylogenetic characterization. Using semi-quantitative RT-PCR, we found that the PeDREB2a was greatly induced by drought, NaCl, low temperature, 1-naphthaleneacetic acid (NAA), 6-benzyl aminopurine (6-BA) and gibberellic acid (GA3) treatments in P. euphratica seedling. Yeast transactivity assay demonstrated that PeDREB2a gene encodes a transcription activator. Overexpression of PeDREB2a under the stress-inducible rd29A promotor in transgenic Arabidopsis and Lotus corniculatus forage plants resulted in enhanced tolerance to salt and drought stresses. The PeDREB2a overexpressing Arabidopsis lines showed higher root length and plant height and had elevated levels of soluble sugars and lower levels of malondialdehyde under stress conditions compared to control plants. The results revealed that PeDREB2a play an essential role as a DREB transcription factor in regulation of stress-responsive signaling in P. euphratica.