Barley (Hordeum vulgare) is an important component of heart-healthy whole grain diets because it contains β-glucan. All current US barley varieties with high β-glucan are spring habit and have waxy starch. Winter varieties have agronomic advantages but require low-temperature tolerance (LTT). Vernalization sensitivity (VS) is associated with higher levels of LTT. To rapidly develop fall-sown varieties with LTT and higher grain β-glucan, we therefore used marker-assisted selection (MAS) at the WX and VRN-H2 loci. The MAS-derived lines, together with unrelated non-waxy germplasm developed via phenotypic selection (PS), were used for a genome-wide association scan (GWAS). The panel was phenotyped for grain β-glucan, LTT and VS. It was genotyped with 3072 single-nucleotide polymorphisms (SNPs) and allele-specific primers. Marker-assisted selection fixed target alleles at both loci but only one of the target phenotypes (higher β-glucan percentage) was achieved. Variation for VS and LTT is attributable to (i) incomplete information about VRN-H1 at the outset of the project and (ii) unexpected allelic variation at VRN-H3 with a large effect on VS and LTT.Keywords: food barley, betaglucan, winter barley, marker assisted selection, vernalization, low temperature toleranceKeywords: food barley, betaglucan, winter barley, marker assisted selection, vernalization, low temperature toleranc
