Structural characterization of the DRF1 gene of Aegilops speltoides and comparison of its sequence with those of B and other Triticeae genomes

The genus Aegilops L. has been intensively investigated due to its close relationship with wheat ( Triticum L.) as contributor of B and D subgenomes. Because of their vast genetic diversity, Aegilops species represent a rich source of alleles of agronomic interest, which could be used to widen the wheat gene pool and improve tolerance to diseases, pests, drought, cold and other environmental stresses. We report the isolation and characterization of the Dehydration Responsive Factor 1 ( DRF1) gene in three accessions of Ae. speltoides coming from different regions of the Fertile Crescent. The DRF1 gene belongs to the DREB gene family and encodes transcription factors which play a key role in plant response to water stress. As in other cereals, the DRF1 gene in Aegilops speltoides consists of four exons and three introns and undergoes alternative splicing. A processed pseudogene was also identified and compared with the sequence of an actual mRNA transcript, breaking new ground in the understanding of the complex regulation mechanism of this gene. The genetic diversity was evaluated by comparison of inter- and intra-species variation among some Aegilops and Triticeae , by considering both the whole gene and exon 4 sequences. The phylogenetic analyses were able to cluster the sequences in well-supported clades attributable to the genomes analysed. The overall results suggest that there is a high similarity between the B and S genome copies of the DRF1 gene but also features indicating that the two genomes have evolved independently.