Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/1995
Publication Date: N/A
Interpretive Summary: The breeding of barley lines having improved malting quality is impeded by the fact that many of the traits needed in malting barleys are not due to single genes, which are easy to manipulate, but are controlled by multiple genes, each of which contribute a small amount to the overall quality. It is hard to manipulate these so-called 'quantitative' genes using conventional breeding methods. One aspect of malting quality that needs to be improved is the ability of barley to rid itself of beta-glucans during malting. High beta-glucan levels cause problems during brewing. This paper reports studies conducted to determine where, on the barley chromosome, the genes controlling the formation and degradation of beta-glucans are located. Nine gene locations were found that determined how much beta-glucan was originally present in the barley and malt, while eight locations determined how much of it was removed by the end of the malting process. The information obtained can now be used by barley breeders to develop malting barleys having improved malting quality.
Technical Abstract: Genetic study of beta-glucan content and beta glucanase activity has been facilitated by recent developments in quantitative trait loci (QTL) analysis. QTL for barley and malt beta-glucan content and for green and finished malt beta-glucanase activity were mapped using a 123-point molecular marker linkage map from the cross of Steptoe/Morex. Three QTL for barley beta-glucan, six QTL for malt beta-glucan, three QTL for beta-glucanase in green malt and five QTL for beta-glucanase in finished malt were detected by interval mapping procedures. The QTL with the largest effects on barley beta-glucan, malt beta-glucan, green malt beta-glucanase and finished malt beta-glucanase were identified on chromosomes 2, 1, 4 and 7, respectively. A genome map based approach allows for dissection of relationships among barley and malt beta-glucan content, green and finished malt beta-glucanase activity, and other malting quality parameters.