Vernalization genes VRN1 play a major role in the transition from vegetative to reproductive growth in wheat. In di-, tetra- and hexaploid wheats the presence of a dominant allele of at least one VRN1 gene homologue (Vrn-A1, Vrn-B1, Vrn-G1 or Vrn-D1) determines the spring growth habit. Allelic variation between the Vrn-1 and vrn-1 alleles relies on mutations in the promoter region or the first intron. The origin and variability of the dominant VRN1 alleles, determining the spring growth habit in tetraploid wheat species have been poorly studied.

The growth habit was investigated for 228 accessions of 12 tetraploid wheat species. The promoter and first intron regions of VRN1 genes were analyzed in 57 spring accessions of 10 tetraploid species. Comparative analysis revealed the novel allele of VRN-A1 (Vrn-A1b.7) and VRN-B1 (Vrn-B1dic). Vrn-A1d was widely distributed across the accessions of T. dicoccoides. In the genetic experiments the dominant mode of inheritance was shown for the Vrn-A1d and Vrn-A1c alleles. It is assumed that the presence of Vrn-A1d allele is associated with the formation of spring growth habit in the 11 accessions of T. dicoccoides. Vrn-B1dic is a unique allele characterized by the unexpected high level of promoter sequence dissimilarity in comparison to the vrn-B1. This allele was identified in the only accession of T. dicoccoides (IG46225) and further investigations are required to determine the role of this allele in the formation of spring growth habit. Novel allelic variants identified in the represent study provide a useful resource for fundamental investigations and could be used in agricultural production to expand the biodiversity of cultivated of wheat species. The summarization of the results regarding to the VRN1 alleles identified to date in di- and polyploid wheat species allowed us to discuss the evolution of the alleles.

The project was supported by the Russian Foundation for Basic Research (Grant No. 16-34-00688)