Malting Quality QTLs in Elite North American Facultative/Winter 6-rowed Barley (Hordeum vulgare L.) – 21 QTLs Identified via GWAS

Malt barley is an economically important crop worldwide. Barley malt quality is difficult to breed for, as it is a combination of complex traits which are time-consuming and expensive to phenotype. This makes marker-assisted selection – and thus quantitative trait locus (QTL) mapping – particularly appealing. We used the Oregon State University and University of Minnesota facultative/winter 6-rowed barley advanced breeding lines to assemble a GWAS panel, named the FAC-WIN6, in part to map malt quality QTLs within our programs. Winter and facultative malt barleys can be sown in fall, which makes them more sustainable in terms of soil erosion and input efficiency. The FAC-WIN6 projects are part of the Triticeae Coordinated Agricultural Project, which works to develop sustainable barley and wheat germplasm that is robust to climate change. We designed a two-year, single location GWAS experiment for twelve malt quality traits. The FAC-WIN6 has 300 lines, with genotypic data for 5,812 polymorphic SNP markers. We report 21 malt quality QTLs across seven traits. Eight of our QTLs appear to be novel. For each QTL, we provide an effect estimate, a representative marker, a candidate gene, and a qualitative confidence level that summarizes ambiguity in the GWAS raw results. Our results are useful for marker-assisted selection, as well as for strengthening the confidence of QTLs mapped in other germplasm.