Ectopic expression of dehydration responsive element binding proteins (StDREB2) confers higher tolerance to salt stress in potato

Dehydration responsive element binding proteins (DREB) are members of a larger family of transcription factors, many of which have been reported to contribute to plant responses to abiotic stresses in several species. While, little is known about their role in potato (Solanum tuberosum). This report describes the cloning and characterization of a DREB transcription factor cDNA, StDREB2, isolated from potato(cv Nicola) plants submitted to salt treatment. Based on a multiple sequence alignment, this protein was classified into the A-5 group of DREB subfamily. Expression studies revealed that StDREB2 was induced in leaves, roots and stems upon various abiotic stresses and in response to exogenous treatment with abscisic acid (ABA). In agreement with this expression pattern, over-expression of StDREB2 in transgenic potato plants resulted in enhanced tolerance to salt stress. These data suggest that the isolated StDREB2 encodes a functional protein involved in plant response to different abiotic stresses. An electrophoretic mobility shift assay (EMSA) indicated that the StDREB2 protein bound specifically to the DRE core element (ACCGAGA) in vitro. Moreover, Semi quantitative RT-PCR analysis revealed that the transcript level of a putative target gene i.e. d1-pyrroline-5-carboxylate synthase (P5CS) was upregulated in transgenic plants submitted to salt stress conditions. A concomitant increase in proline accumulation was also observed under these conditions. Taking together, all these data suggest that StDREB2 takes part in the processes underlying plant responses to abiotic stresses probably via the regulation of ABA hormone signaling and through a mechanism allowing proline synthesis

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

International audienceIt has been established that drought-responsiveelement binding (DREB) proteins correspond to transcriptionfactors which play important regulatory roles in plant response to abiotic and biotic stresses. In this study, a novel cDNA encoding DREB transcription factor, designatedStDREB1, 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-quantitativeRT-PCR showed that StDREB1 is expressed in leaves,stems, and roots under stress conditions and it is greatlyinduced by NaCl, drought, low temperature, and abscisicacid (ABA) treatments. Overexpression of StDREB1 cDNAin transgenic potato plants exhibited an improved salt anddrought stress tolerance in comparison to the non-transformed controls. The enhanced stress tolerance may beassociated with the increase in P5CS-RNA expression (d1-pyrroline-5-carboxylate synthetase) and the subsequentaccumulation of proline osmoprotectant in addition to abetter control of water loss. Overexpression of StDREB1also activated stress-responsive genes, such as thoseencoding calcium-dependent protein kinases (CDPKs), intransgenic potatoes under standard and high salt conditions.These data suggest that the StDREB1 transcription factor isinvolved in the regulation of salt stress tolerance in potato by the activation of different downstream gene expression

Identification and functional characterization of ten AP2/ERF genes in potato

International audienceEthylene-responsive element-binding factors (ERF) constitute one of the largest transcription factor families in plants. In this study, we describe the cloning and the characterization of ten cDNAs encoding ERF factors from potato. The alignment of their AP2/ERF (Apetala2/ethylene-responsive factor) domain led to the identification of six StERFs (Solanum tuberosum ERFs) and four StDREBs (dehydration responsive element binding). The phylogeny and the sequence characterization allowed the classification of these StERFs into five ERF families. Expression analysis by semi-quantitative RT-PCR of these genes revealed that most of them are induced by hormone treatment such as abscisic acid, ethephon, jasmonic acid and salicylic acid. However, salt stress induced the expression of all StDREB but only three StERF genes. These results suggest that these transcription factors are involved in salt stress response. The StDREB1 and StDREB2 genes showed strong increase in expression in response to drought stress. In an attempt to improve drought tolerance in potato, we overexpressed StDREB1 and StDREB2 in transgenic potato plants (S. tuberosum L. Group Tuberosum) cv. Belle de Fontenay (BF15) and Spunta, respectively. The level of drought tolerance of these transgenic lines was significantly greater than that of wild-type control plants as measured by relative water content H2O2 content, free proline and total soluble sugars. The results suggest that the StDREB1 and StDREB2 as AP2/ERF transcription factors may play dual roles in response to drought stress in potato