Molecular genetical characterization of vernalization genesVrn-A1, Vrn-B1andVrn-D1in spring wheat germplasm from Russia and adjacent regions

Abstract

We characterized a representative set of 42 spring wheat cultivars from Russia and adjacent regions for 3 Vrn loci. The 42 genotypes were screened, along with 3 genotypes of known Vrn genes, using previously published genome-specific polymerase chain reaction (PCR) primers designed for detecting the presence or absence of dominant or recessive alleles of the major Vrn loci: Vrn-A1, Vrn-B1 and Vrn-D1. The dominant promoter duplication allele Vrn-A1a was present in 28 of 42 cultivars, whereas the promoter deletion allele Vrn-A1b was present in only 1 of the Russian cultivars (Triticum aestivum L. ‘Pyrothrix 28’). The intron deletion allele Vrn-A1c was not present in any tested cultivar. The dominant Vrn-D1 allele was found in 1 of the cultivars. Thirteen of the spring wheat cultivars tested here carry the recessive vrn-A1 allele. However, for 6 cultivars, there were inconsistencies between PCR data and genetic segregation analysis, showing the presence of the dominant Vrn-A1 gene. No inconsistencies were found in the case of Vrn-B1 locus. A new combination of specific primers allowed amplification of the common Vrn-B1a allele along with the novel Vrn-B1c allele, which was present in 17 of the studied cultivars (40%). Twenty-five cultivars (59%) had dominant alleles of Vrn-A1a and Vrn-B1 in combination. We showed the predominance of the Vrn-B1c allele among cultivars with monogenic control of vernalization in West Siberia and Kazakhstan. In the absence of epistatic effects of Vrn-A1, this allele causes an earlier heading time compared to Vrn-B1a, thereby avoiding early fall frosts. Suggestions are made concerning the origin and distribution of the Vrn-B1c allele among Russian spring wheats.