Quantitative trait loci and epistasis for crown freezing tolerance in the 'Kanota' x 'Ogle' hexaploid oat mapping population

Crown freezing tolerance is the most important factor conferring oat (Avena spp.) winter hardiness. The objective of this study was to identify quantitative trait loci (QTL) for crown freezing tolerance in the 'Kanota' x 'Ogle' recombinant inbred line (RIL) mapping population and to examine their relationship with other winter hardiness traits. One hundred thirty-five RILs were evaluated for crown freezing tolerance in a controlled environment. Previously published molecular marker and linkage map information was used for QTL detection. Seven QTL and four complementary epistatic interactions were identified that accounted for 56% of the phenotypic variation. Ogle contributed alleles for increased crown freezing tolerance at three loci, while Kanota contributed alleles for increased crown freezing tolerance at four loci. All loci where Kanota alleles increased crown freezing tolerance showed complementary epistasis for decreased crown freezing tolerance with the QTL near UMN13. Two of the major QTL identified were in the linkage groups (LG) associated with a reciprocal translocation between chromosomes 7C and 17, which was previously associated with spring growth habit in oat. The results confirm the importance of the chromosomes involved in the reciprocal 7C-17 translocation in controlling winter hardiness component traits.