Marker-based selection of QTL affecting grain and malt quality in two-row barley

Malt quality traits of barley (Hordeum vulgare L.) may be suitable candidates for marker-assisted selection, as their evaluation involves laborious and costly procedures. Four regions of the genome were previously reported to affect several grain and malt quality traits in the two-row barley cross 'Harrington'/'TR306'. This study used an independent set of lines derived from the same cross to verify the existence of quantitative trait loci (QTL) in these regions. Molecular marker genotypes were used to select 47 lines from among 410 Harrington/TR306 lines that had not been used in the original mapping experiment. Four groups of lines were selected on the basis of their genotype at marker loci in two regions on chromosome 7 (5H) with QTL affecting kernel weight and plumpness, grain protein, extract beta-glucan content, the difference between fine-grind and coarse-grind extract, soluble protein, diastatic power, alpha-amylase activity and fine-grind extract, and in regions on chromosomes 3 (3H) and 6 (6H) with QTL affecting extract beta-glucan content and fine-coarse difference. Grain and malt quality traits of these lines were determined from grain grown in five field environments in western Canada. The results confirmed the presence of QTL on chromosome 7 affecting all traits previously reported. Marker-based selection for two regions on chromosome 7 was effective in identifying phenotypically superior lines, and the magnitudes of the combined effects for these regions were close to the estimates calculated in the mapping experiment. The presence of QTL on chromosomes 3 and 6 could not be confirmed as categorically, but combined selection for extract beta-glucan content and fine-coarse difference at all four QTL regions was more effective than selection for only the two regions on chromosome 7.