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Submitted to: Symposium Proceedings
Publication Type: Abstract Only Publication Acceptance Date: 10/25/2007 Publication Date: 10/25/2007 Citation: Riday, H. 2007. Marker Assisted Selection in Legumes. In: Proceedings of International Workshop - Integrating Genomics into Plant Breeding, October 25-26, 2007, Porto Alegre, Brazil. Lotus Newsletter. 37(3):102. Interpretive Summary: Technical Abstract: Marker assisted selection (MAS) has begun to be implemented in some self-pollinating crops such as wheat. The promise of MAS has been on the breeding horizon for over two decades now. With the advent of the Medicago truncatula and Lotus japonicus genome sequences; numerous SSR mapped markers in M. truncatula, Medicago sativa, Trifolium pratense, and Trifolium repense; and various EST projects in forage legume species a good genomic infrastructure has been developed. In this context an exploratory integrated QTL discovery and selection scheme has been implemented in T. pratense. T. pratense (red clover) is a diploid outbreed species with limited breeding resources due to smaller seed market share, with biomass yield and plant persistence being the overwhelming traits of breeding interest. This makes red clover an ideal test case for determining feasibility both scientifically and economically of MAS. An analysis of a recurrent halfsib selection scheme overlaid with a concurring recurring linkage disequilibrium (LD) QTL discovery and MAS scheme shows substantial increased genetic gain per cycle could be achieved for difficult to phenotype and highly quantitative trait such as persistence. However, taking molecular technology costs into account, with correspondingly reduced field evaluation expenditures make MAS selection schemes genetic gains much more marginal. One of the most powerful uses of molecular markers in a halfsib recurrent selection scheme would be to increase parental control by identifying male paternity for paternity truncation selection within field selected halfsib lines. LD QTL discovery methods fit very nicely into a recurrent halfsib selection scheme, since almost any marker associations with the trait (real or population structure induced) can be used for either parental control improvement or QTL enrichment. Reducing genotyping costs to $0.03 USD or less per marker per genotype would make MAS very competitive in red clover persistence selection. Even at current costs estimates of over $0.30 USD per marker per genotype MAS could play a profitable role in paternity identification and selection schemes. |
