Mapping and validation of chromosome regions associated with high malt extract in barley (Hordeum vulgare L.)

Malt extract represents the soluble material extracted from malt during the mashing process of barley. The measurement of malt extract is used by maltsters and brewers to assess the quality of the barley they are purchasing and is therefore one of the most important parameters used by breeders to assess the quality of new barley varieties before release. This paper identifies and investigates several regions ( quantitative trait loci, QTLs) found to be associated with malt extract and discusses the uses of these regions for marker assisted selection ( MAS). Eight regions of the barley genome were found to be associated with malt extract in 3 mapping populations. Five regions were found in the Sloop/ Alexis and Sloop- sib/ Alexis mapping populations on chromosomes 1H, 2H, 3H, 4H, and 5H. Two regions were found in the Chebec/ Harrington population on chromosomes 1H and 5H and a single region was found on chromosome 2H in the Galleon/ Haruna Nijo mapping population. Markers from 6 of these regions were investigated using several breeding populations with a high malt extract variety as a parent. The ' allele' from the high malt extract parent was found to be associated with a significant increase in malt extract in 4 regions, 2 regions on chromosome 2H and 2 regions on chromosome 5H.