Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 6, 1996
Publication Date: N/A
Interpretive Summary: The use of DNA markers to increase the speed and efficiency of breeding programs for selecting desirable traits in barley has been proposed. For these markers to be used, they must show differences between different types of barley. We examined how many differences DNA markers identified between 28 North American barley types. While 57% of the markers identified differences among all 28 barleys, only 17% identified differences between currently grown Midwestern malting barley types. The low levels of diversity will limit the use of these DNA markers in selecting for complex traits such as yield and malt quality. These markers will most likely be of most use in selecting for simple traits, such as disease resistance, which often come from more diverse barley types.
Technical Abstract: Genetic linkage maps of molecular markers have been developed for barley (Hordeum vulgare L.) to aid development of improved barley cultivars. But the crosses between genetically diverse parents used to maximize polymorphism in map construction are not appropriate for use in breeding programs for cultivar development. The objective of this study was to determine whether the amount of genetic variation detected at RFLP marker loci among 28 North American (NA) spring barley cultivars was sufficient to permit molecular marker-assisted selection (MMAS) in NA barley breeding programs. DNA extracted from these cultivars was restriction digested with BamHI and hybridized to 100 clone sequences mapped by the North American Barley Genome Mapping Project. A diversity index (DI) was calculated for each clone sequence based on the number and frequency of RFLP patterns detected. Fifty-seven of the clones detected RFLPs among these cultivars. Twenty-nine of these were highly informative (DI>0.500) in detecting differences between the 28 cultivars. Clone sequences were identified that separated the 28 cultivars by geographic origin (Western vs. Midwestern) and by spike morphology (2-rowed vs. 6-rowed). While 47% of the clone sequences detected RFLPs among the 15 Midwestern 6-rowed cultivars, only 17% detected RFLPs among the recently released cultivars Robust, Excel, Foster, and Stander. This low level of RFLP between typical parental cross combinations will limit the use of MMAS for yield and malt quality. The use of MMAS in malting barley breeding programs will likely be limited to the incorporation of qualitative traits, such as disease resistance genes, from less adapted germplasm.