Prediction and validation of DREB transcription factors for salt tolerance in Solanum lycopersicum L.: An integrated experimental and computational approach

Abstract

The dehydration responsive element binding (DREB) transcription factors (TFs) have been intensely reported toregulate plant growth and defence response under stress condition. In this study, we have investigated impact ofsalt stress (400 mM) at vegetative stage in tomato hybrids on (1) several yield and related components (2)relative water content, membrane stability (3) enzymatic activity and gene expression levels of stress responsive genesand since in tomato, little is known about its functional binding motifs, protein-protein interactions and core amino acid residues involved in the regulation of its expression under stress condition (4)we also used insilico approach to structurally and functionally characterize tomato DREB1 protein in response to salt stress. Salt stress imposed at vegetative stage caused significant reduction in relative water content, chlorophyll content,proline content, expression of stress responsive genes and enhanced membrane damage in all the hybrids.However, hybrids viz., VRTH-1754 and VRTH-1755 showed remarkable tolerance to salt stress as they showed low membrane damage, increased proline content and enhanced activity of antioxidant enzyme along with expression of stress responsive genes. Phylogenetic foot-printing, multiple sequence alignment, and motif analysis of S. lycopersicum DREB1 (SlDREB1) reveal remarkable similarities with its wild homologue showing monophyletic origin with S. pimpinellifolium and close relation with S. pennelli and S. tuberosum. Additionally, DNA-protein interaction study revealed that the SlDREB1 protein binds to Dehydration Responsive Element (DRE) DNA element through conserved KYRG region of AP2/ERF domain with flanking sequences viz., Tyr49,Gly50, Pro51, Cys52, and Arg54.Furthermore, gene ontology (GO) analysis predicted the most significant subcellular localization of SlDREB1 protein to the chloroplast (32.9%) followed by nucleus (28.9%) and cytoplasm (17.6%) revealing that SlDREB1 proteins were mainly involved in ethylene mediated signalling pathway, transcription initiation and defence response.