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.