Genome-Wide Identification and Expression Profiling of the ABF Transcription Factor Family in Wheat ( L.).

Members of the abscisic acid (ABA)-responsive element (ABRE) binding factor (ABF) and ABA-responsive element binding protein (AREB) families play essential roles in the regulation of ABA signaling pathway activity and shape the ability of plants to adapt to a range of stressful environmental conditions. To date, however, systematic genome-wide analyses focused on the ABF/AREB gene family in wheat are lacking. Here, we identified 35 genes in the wheat genome, designated - according to their chromosomal distribution. These genes were further classified, based on their phylogenetic relationships, into three groups (A-C), with the genes in a given group exhibiting similar motifs and similar numbers of introns/exons. Cis-element analyses of the promoter regions upstream of these revealed large numbers of ABREs, with the other predominant elements that were identified differing across these three groups. Patterns of gene expansion were primarily characterized by allopolyploidization and fragment duplication, with purifying selection having played a significant role in the evolution of this gene family. Further expression profiling indicated that the majority of the genes from groups A and B were highly expressed in various tissues and upregulated following abiotic stress exposure such as drought, low temperature, low nitrogen, etc., while some of the genes in group C were specifically expressed in grain tissues. Regulatory network analyses revealed that four of the group A s (, , , and ) were centrally located in protein-protein interaction networks, with 13 of these genes being regulated by 11 known miRNAs, which play important roles in abiotic stress resistance such as drought and salt stress. The two primary upstream transcription factor types found to regulate gene expression were BBR/BPC and ERF, which have previously been reported to be important in the context of plant abiotic stress responses. Together, these results offer insight into the role that the genes play in the responses of wheat to abiotic stressors, providing a robust foundation for future functional studies of these genes.