| Barley (Hordeum vulgare L.) has been a fundamental component of ancient and modern agriculture not just for its environmental flexibility but also because of its use in the production of malt. A key factor affecting malting is seed dormancy, or the failure of an undamaged seed to germinate when exposed to adequate conditions for germination. Other factors that directly influence malt quality are levels of alpha-amylase, diastatic power (DP), soluble protein, Kolbach Index, malt extract, and wort beta-glucan; concentration of the fermentable sugars maltose, glucose, fructose, and maltotriose; and the concentration of the mycotoxin deoxynivalenol (DON). The aim of this research was to determine and tag by DNA markers the genetic basis for agronomic performance, seed dormancy, malt quality, fermentable sugars, and DON accumulation in an F1-derived doubled-haploid population from two closely related barley cultivars, Stander and Robust, that differ in the aforementioned traits. Stander is a non-dormant cultivar that produces high levels of alpha-amylase, DP, and soluble protein, and Robust is a dormant cultivar that produces moderate levels of these traits. A 168 marker linkage map covering 795 cM was developed and used to identify several Quantitative Trait Loci (QTL) not previously reported, including QTL for Free Amino Nitrogen (FAN) on chromosomes 5H and 6H, wort color on chromosomes 2H and 5H, and soluble protein and Kolbach index on chromosome 6H. For each of these traits, the allele coming from Stander increased the phenotypic mean. A unique aspect of the present research was the genetic mapping for the first time of fermentable sugars. QTL for these sugars mapped to chromosomes 4H, 5H and 6H. Of these, a QTL near the telomere on the long arm of chromosome 5H and the one near the centromeric region of chromosome 6H also regulate the levels of alpha-amylase activity, DP, Kolbach Index, wort protein, FAN, and wort color, traits that differentiate the cultivar malt quality needs of Anheuser-Busch InBev and MillerCoors. From these QTL the one located between the microsatellite marker scssr0937 and the telomere of the long arm of chromosome 5H is also controlling seed dormancy. |
