Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2005
Publication Date: 1/24/2006
Citation: Stendal, C.A., Casler, M.D., Jung, G. 2006. Marker-assisted and phenotypic selection for neutral detergent fiber concentration in smooth bromegrass. Crop Science. 46:303-311. Interpretive Summary: Neutral detergent fiber (NDF) content of forages limits the consumption of grass by livestock. In a previous study, we found 16 DNA markers were associated with NDF levels in smooth bromegrass (Bromus inermis L.) populations. We confirmed in this study that some of these markers are closely associated with NDF levels of individual plants. From this information, we created some DNA fingerprints that can be used to breed new varieties of bromegrass with reduced NDF levels. The use of DNA fingerprints should streamline the process of developing varieties with low NDF levels. These results are of value to other scientists, because they provide only the second confirmation that DNA markers can be used to develop new varieties of forage crops with improved nutritional value for livestock.
Technical Abstract: Neutral detergent fiber (NDF) is the most effective and measurable predictor of animal intake. About 70% of the variation in animal production is attributed to differences in intake potential of livestock feed. Sixteen molecular markers associated with NDF in four divergently selected smooth bromegrass (Bromus inermis L.) populations were selected from a previous study for further examination for possible use in a marker-assisted selection (MAS) breeding program. The objectives of this experiment were to confirm the association of previously identified markers to NDF concentration in smooth bromegrass populations and to develop a marker-based selection index. Marker and NDF data were analyzed and marker-indices were constructed using data from the current and previous studies. Index scores were used to rank genotypes and create selection differentials using phenotypic data. Marker frequencies calculated on a subpopulation basis between the previous and current studies were highly unrepeatable. Nevertheless, of the fourteen groups of marker indices, seven of which accounted for pedigree structure, one marker index appears to provide the greatest potential for use in MAS to reduce NDF across all four populations of smooth bromegrass. Where pedigree structure is known, selections made using this index would lead to the largest expected response per year and eliminate the need to collect phenotypic data for as long as linkage relationships remain intact. Where pedigree structure is unknown a general marker index may be used, or phenotypic data can be utilized along with a marker index. However, inclusion of phenotypic data would necessitate a cost/benefit analysis.