Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2005
Publication Date: 10/1/2005
Citation: Curley, J., Sim, S.C., Warnke, S.E., Leong, S.A., Barker, R.E. and Jung, G. 2005. QTL mapping of resistance to gray leaf spot in ryegrass. Journal of Teoretical and Applied Genetics. 111:1107-1117. Interpretive Summary: Gray leaf spot is a serious fungal disease recently reported on perennial ryegrass an important turf and forage grass species. The fungus that causes gray leaf spot also causes rice blast and many other grass diseases. One of the best ways to control gray leaf spot is to identify resistance and then develop new cultivars that contain this resistance. Resistance to gray leaf spot has been identified in a ryegrass population developed by crossing two different ryegrass species. The chromosome regions that influence this resistance have been identified and methods of transferring this resistance to ryegrass cultivars are being developed.
Technical Abstract: Gray leaf spot (GLS) is a serious fungal disease recently reported on the important turfgrass and forage species, perennial ryegrass (Lolium perenne L.) caused by Magnaporthe grisea, which also causes rice blast and many other grass diseases. Rice blast is usually controlled by host resistance, but durability of resistance is a problem. Little GLS resistance has been reported in perennial ryegrass. However, greenhouse inoculations in our lab using one ryegrass isolate and one lab strain suggest partial resistance is present and segregating in an annual x perennial ryegrass pseudo-F2 mapping population. A high density linkage map of this population has been constructed using AFLP, RAPD, tall fescue EST-SSR, and syntenic RFLP anchor probe markers, and the phenotypic segregation observed allows quantitative trait locus (QTL) mapping of GLS resistance. Potential QTL of varying effect have been detected on at least four linkage groups. This work will likely benefit US turf growers, by allowing improvement of GLS resistance in perennial ryegrass through marker-assisted selection based breeding. It will also increase our knowledge of this emerging turf disease and the genetics of resistance to this disease.