Seed dormancy in barley: identifying superior genotypes through incorporating epistatic interactions

A genetic linkage map of barley with 128 molecular markers was constructed using a doubled haploid (DH) mapping population derived from a cross between barley (Hordeum vulgare) cvv. Stirling and Harrington. Quantitative trait loci controlling seed dormancy were characterised in the population. A major quantitative trait locus (QTL) controlling seed dormancy and accounting for over half the phenotypic variation (52.17%) was identified on the distal end of the long arm of chromosome 5H. Minor QTLs were also detected near the centromeric region of 5H and on chromosomes 1H and 3H. These minor QTLs with additive effects accounted for 7.52% of the phenotypic variance measured. Examination of epistatic interactions further detected additional minor QTLs near the centromere of 2H and on the long arm and short arms of 4H. Combinations of parental alleles at the QTL locations in predictive analyses indicated dramatic differences in germination. These results emphasise the potential differences in dormancy that can be achieved through the use of specific gene combinations and highlights the importance of minor genes and the epistatic interactions that occur between them. This study found that the combination of Stirling alleles at the two QTL locations on the 5H chromosome and Harrington alleles at the 1H and 3H QTL locations significantly produced the greatest dormancy. Uncovering gene complexes controlling the trait may enable breeders to produce superior genotypes with the desirable allele combinations necessary for manipulating seed dormancy in barley.