Overexpression of StDREB1 Transcription Factor Increases Tolerance to Salt in Transgenic Potato Plants

Abstract

It has been established that drought-responsive element binding (DREB) proteins correspond to transcription factors which play important regulatory roles in plant response to abiotic and biotic stresses. In this study, a novel cDNA encoding DREB transcription factor, designated StDREB1, was isolated from potato (Solanum tuberosum L.). This protein was classified in the A-4 group of DREB subfamily based on multiple sequence alignments and phylogenetic characterization. Semi-quantitative RT-PCR showed that StDREB1 is expressed in leaves, stems, and roots under stress conditions and it is greatly induced by NaCl, drought, low temperature, and abscisic acid (ABA) treatments. Overexpression of StDREB1 cDNA in transgenic potato plants exhibited an improved salt and drought stress tolerance in comparison to the non-transformed controls. The enhanced stress tolerance may be associated with the increase in P5CS-RNA expression (δ (1)-pyrroline-5-carboxylate synthetase) and the subsequent accumulation of proline osmoprotectant in addition to a better control of water loss. Overexpression of StDREB1 also activated stress-responsive genes, such as those encoding calcium-dependent protein kinases (CDPKs), in transgenic potatoes under standard and high salt conditions. These data suggest that the StDREB1 transcription factor is involved in the regulation of salt stress tolerance in potato by the activation of different downstream gene expression.

The StDREB1 transcription factor is involved in oxidative stress response and enhances tolerance to salt stress

“…We have previously shown that overexpression of StDREB1 in transgenic potato plants increases the accumulation of the proline osmoprotectant by activating expression of d1-pyrroline-5-carboxylate synthetase (P5CS) gene (Bouaziz et al 2013). Similar results were also observed in transgenic alfalfa plants overexpressing GmDREB1 that showed an increase in the P5CS gene expression (Jin et al 2010).…”

“…Our previous results suggested that the StDREB1 factor may belong to this group of transcription factors that activate the expression of genes harboring both the GCC box and DRE target sequences (Bouaziz et al 2013). To further confirm this hypothesis, a recombinant HisStDREB1 protein was overexpressed in E. coli.…”

“…In vitro cultivated plants from two commercial potato (Solanum tuberosum L.) cultivars, Belle de Fontenay (BF15) and Nicola, and transgenic plants overexpressing StDREB1 gene (Bouaziz et al 2013) were propagated in a solid MS basal medium (Murashige and Skoog 1962) supplemented with vitamins (Morel and Wetmore 1951) in a growth chamber (22°C, 16 h light/8 h dark) under 250 mE/m 2 /s light intensity.…”

“…Total RNA was isolated from in vitro-cultivated potato plants submitted to the different stress conditions and semiquantitative RT-PCRs were carried as described by Bouaziz et al (2013).…”

“…In a previous study, we reported that the overexpression of the StDREB1 transcription factor enhances salt and drought stress tolerance in potato plants (Bouaziz et al 2013). In the present study, we demonstrate the ability of StDREB1 to bind to the both DRE and GCC box of target gene promoters.…”