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Title: QTL ANALYSIS OF MALTING QUALITY IN BARLEY BASED ON THE DOUBLED HAPLOID PROGENY OF TWO ELITE NORTH AMERICAN VARIETIES REPRESENTING DIFFERENT GERMPLASM GROUPS

Author
item MARQUEZ-CEDILLO, L - OREGON STATE UNIVERSITY
item HAYES, P - OREGON STATE UNIVERSITY
item Jones, Berne
item KLEINHOFS, A - WASHINGTON STATE UNIV.
item LEGGE, W - AGRIC. CANADA
item ROSSNAGEL, B - UNIV. OF SASKATCHEWAN
item SATO, K - OKAYAMA UNIVERSITY
item ULLRICH, S - WASHINGTON STATE UNIV.
item Wesenberg, Darrell

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: The breeding of barley lines that have 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. This paper reports on one way to use molecular biology to detect these genes and to incorporate them into improved varieties. A 2-rowed and a 6-rowed malting barley were crossed and the resulting plants were analyzed for several malting quality traits. Seventeen otherwise undetectable gene locations affecting malting quality were found. Several of these affected multiple malting quality aspects. Genes affecting nearly all aspects of malting quality were located at the same place as the gene(s) that determine whether a barley is 2- or 6-rowed, ,and these genes were the strongest ones found. This experiment shows that crossing 2-rowed and 6-rowed barleys can cause problems by disrupting the normal balance of characteristics found in both barley types, but that the information gained will be useful in helping breeders maintain the characteristics that are critical for developing new barleys that have improved malting quality.

Technical Abstract: This study was conducted to determine the number, genome location and effects of QTLs for malting quality in the two North American barley quality standards. Using a doubled haploid population of 140 lines from the cross of Harrington x Morex, malting quality phenotype data sets from eight environments, and a 107-marker linkage map, QTL analysis were performed. Seventeen QTLs were associated with seven grain and malting quality traits (percentage of plump kernels, test weight, grain protein percentage, soluble/total (S/T) protein ratio, a-amylase activity, diastatic power and malt extract percentage). QTLs for multiple traits were coincident. The loci controlling inflorescence type were coincident with QTLs affecting all traits except malt extract percentage. The largest effect QTLs, for percentage of plump kernels, test weight, grain protein percentage, S/T ratio, and diastatic power, were coincident with the mV locus. QTL analyses were conducted separately for each sub-population (six-rowed and two-rowed). There were significant interactions between the mV and mi loci for grain protein percentage and S/T protein ratio. Apparently this mating of two different germplasm groups caused a disruption of the balance of traits. Information on the number, position and effects of QTLs determining components of malting quality may be useful for maintaining specific allele configurations that determine target quality profiles.