Distribution of different Vrn-B1 alleles in hexaploid spring wheat germplasm

In wheat, the transition from the vegetative to reproductive stage is primarily controlled by the series of vernalisation (Vrn-1) genes located on the homoeologous group 5 chromosomes. Up to 2009, only two alleles at the Vrn-B1 locus were known: one dominant, spring, allele (now designated Vrn-B1a) and the other recessive, winter, (vrn-B1) allele. Recently, two additional dominant alleles, Vrn-B1b and Vrn-B1c, were described. In this study, we screened a range of hexaploid spring wheat germplasms for the presence of different Vrn-B1 alleles using new diagnostic molecular markers. Our results show that the Vrn-B1a allele was the most prevalent, being present in 55.3 % of the 2,495 accessions examined, followed by the recessive vrn-B1 allele, which occurred in 31.5 % of the accessions. The novel alleles Vrn-B1b and Vrn-B1c were found in 5.3 and 7.9 % of all accessions, respectively.