Using soybean pedigrees to identify genomic selection signatures associated with long-term breeding for cultivar improvement

Abstract

Genetic hitchhiking methods used to uncover selection signatures related to traits of agronomic importance in crops have primarily been used at the level of domestication by comparing groups of wild germplasm to landraces or elite breeding lines. In this study, two groups of cultivars defined by an elite Canadian soybean cultivar, ‘OAC Bayfield’, were compared to identify selection signatures related to long-term breeding within a specific region. Cultivars were assigned to either a pre- or post-OAC Bayfield group. Of the 162 simple sequence repeat markers used to genotype members of the pedigree, 14 were fixed and 19 exhibited a selective signature. An in silico analysis compared the results in this study to quantitative trait loci (QTL) reported in SoyBase and showed that 18 out of the 19 markers with a selective signature were associated with at least one QTL. From the 80 QTL associated with the 18 markers, half were related to plant architecture, yield, or maturity. In addition, the number and type of QTL associated with the fixed versus selected loci differed, particularly for yield. Genomic regions exhibiting a selection signature may contain important loci that either need to be conserved for agronomic performance or be targeted for introgressive breeding and germplasm enrichment.