Veery wheats carry an allele of Vrn-A1 that has implications for freezing tolerance in winter wheats

Two winter alleles of Vrn-A1 were recently found in wheat cultivars adapted to the Great Plains of the USA. Using a diagnostic marker for a single-nucleotide polymorphism (SNP) in exon 4, which distinguishes the alleles, the allele in the Great Plains cultivar 'Jagger' was common in Australian and CIMMYT cultivars, but 'Veery' cultivars carried the alternate allele from their Russian ancestor, which was the same as the allele in the Great Plains cultivar 'Wichita'. The 'Wichita' allele was in North American winter cultivars, and chromosome substitution lines with a high level of tolerance to freezing, but not in substitution lines with a lower level of tolerance. The SNP between the alleles alters the predicted Vrn-A1 protein sequence, and this potentially explains differences in freezing tolerance. We suggest that these winter alleles could be coded as Vrn-A1v for the 'Jagger' allele and Vrn-A1w for the 'Wichita' allele. Cultivars with the spring Vrn-A1a or Vrn-A1b alleles carried the same SNP allele as 'Jagger', suggesting that the mutation from winter to spring for these alleles occurred in a Vrn-A1v genotype.