Isolation and characterization of dehydration-responsive element-binding factor 2 (DREB2) from Indian wheat (Triticum aestivum L.) cultivars

Abstract

Plants have developed a sophisticated stress response system to cope with and adapt to different types of abiotic stress imposed by the frequenlty adverse environmets. It is essential to understand plants stress response mechanisms in the attempt to improve crop yield under stressful condition. Dehydration responsive element binding (DREB) proteins are important transcription factors known to regulate diverse processes of plant development and stress responses. In this study, DREB2 gene was amplified using specific primer from a diverse set of bread wheat cultivars. PCR products were purified using a gel extraction kit and sequenced. Obtained sequences were aligned and submitted to the NCBI database with HQ804651-55, FC556845-53 accession numbers. Alignment of corresponding amino acid sequences showed conservation of AP2 domain in Indian wheat genotypes. Transcripts level of the genes were shown to be most abundant (17%) in leaves, followed by flower (11%) and the least abundant in stem and seed (8%). To understand the structure function relationships, tertiary structure of DREB2 protein from wheat were built by homology modelling based on the crystal structure of GCC-box binding domain of Arabidopsis thaliana. Predicted models were refined by energy minimization and further validated by Procheck and root mean square deviation (RSMD) value. This is the first documentation of the 3-D model of DREB2 in wheat which is extremely reliable and stable. More similarities were found between AP2/EREBP protein of A. thaliana and T. aestivum by conducting protein docking with the DNA containing GCC-box. A protein was found to interact through their β-sheet, with the major DNA groove by hydrogen and hydrophobic bond, which provides structural stability to the molecule. Data generated in this study will be useful for conducting genomic research to determine the precise role of the AP2/ERF gene under water stress responses with the ultimate goal of improving crops.