Mapping genes controlling variation in barley grain protein concentration

Grain protein concentration is an important determinant of grain quality in many crops, including wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). While high grain protein percentage might be desirable in barley destined for monogastric feed, low grain protein concentration is desirable for malt and beer production. Low grain protein concentration is associated with increased levels of malt extract and reduced problems with beer chill haze. Molecular markers were used to map and characterize the genes responsible for low, stable grain protein concentration in a recombinant inbred line population developed from a cross between 'Karl' (CIho 15487). a low grain protein six-rowed barley, and Lewis' (Clho 15856), a standard two-rowed cultivar. Three major quantitative trait loci (QTL) were identified which impacted grain protein percentage. Two of these grain protein effects appeared to result from gene action impacting flowering date. This pleiotropic relationship may be the main reason agronomically acceptable, low protein cultivars have yet to be released.