Cloning and characterization of a putative orthologue of the wheat vernalization (VRN1) gene in perennial wheatgrass (Agropyron cristatum)

Flowering time is important in the adaptation of crop plants to different environments and impacts the economic value of agricultural crops. Wheatgrass is a perennial Triticeae species and one of the most important grasses for pasture and forage in temperate regions of the world. Late heading is of interest in forage crop breeding programmes. Increasing the time to heading by molecular means may be facilitated by the identification and characterization of floral genes. In addition, the characterization of orthologous genes in wheatgrass is useful for establishing genetic relationships between grasses. In this study, we characterized a wheatgrass orthologue of the hexaploid wheat VRN-A1 gene involved in the vernalization response. High sequence similarity of this gene, designated VRN-P1, to both VRN-A1 and VRN-H1 and its localization on the 5PL chromosome arm in Agropyron cristatum indicated that VRN-P1 is orthologous to VRN1 from wheat and barley. VRN-P1 retains the VRN1 exon/intron organization and encodes a MADS-box transcription factor. Phylogenetic and amino acid analyses confirmed that the isolated sequence represents VRN1. Furthermore, phylogenetic analysis of the deduced protein sequence revealed an intimate genetic relationship between VRN-P1 and VRN1 from Triticeae species.