EST-derived SSR markers used as anchor loci for the construction of a consensus linkage map in ryegrass (Lolium spp.)
1 Department of Genetics and Biotechnology, Faculty of Agricultural Sciences, Research Centre Flakkebjerg, Aarhus University, Forsøgsvej 1, 4200 Slagelse, Denmark
2 Agroscope Reckenholz-Tänikon, Research Station ART, Reckenholzstr. 191, 8046 Zurich, Switzerland
3 Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit - Growth and Development, Caritasstraat 21, 9090 Melle, Belgium
4 Institut National de Recherche Agronomique (INRA) - UR4 Unité de recherche pluridisciplinaire prairies et plantes fourragères, BP6, 86600 Lusignan, France
5 Crops Research Centre Oak Park, TEAGASC, Carlow, Ireland
6 Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, UK
7 Wageningen UR Plant Breeding, Wageningen University and Research Centre (PRI), P.O. Box 16, 6700 AA Wageningen, The Netherlands
8 Department of Agronomy, Iowa State University, 1204 Agronomy Hall, 50011 Ames, IA, USA
BMC Plant Biology 2010, 10:177 doi:10.1186/1471-2229-10-177Published: 16 August 2010
Genetic markers and linkage mapping are basic prerequisites for marker-assisted selection and map-based cloning. In the case of the key grassland species Lolium spp., numerous mapping populations have been developed and characterised for various traits. Although some genetic linkage maps of these populations have been aligned with each other using publicly available DNA markers, the number of common markers among genetic maps is still low, limiting the ability to compare candidate gene and QTL locations across germplasm.
A set of 204 expressed sequence tag (EST)-derived simple sequence repeat (SSR) markers has been assigned to map positions using eight different ryegrass mapping populations. Marker properties of a subset of 64 EST-SSRs were assessed in six to eight individuals of each mapping population and revealed 83% of the markers to be polymorphic in at least one population and an average number of alleles of 4.88. EST-SSR markers polymorphic in multiple populations served as anchor markers and allowed the construction of the first comprehensive consensus map for ryegrass. The integrated map was complemented with 97 SSRs from previously published linkage maps and finally contained 284 EST-derived and genomic SSR markers. The total map length was 742 centiMorgan (cM), ranging for individual chromosomes from 70 cM of linkage group (LG) 6 to 171 cM of LG 2.
The consensus linkage map for ryegrass based on eight mapping populations and constructed using a large set of publicly available Lolium EST-SSRs mapped for the first time together with previously mapped SSR markers will allow for consolidating existing mapping and QTL information in ryegrass. Map and markers presented here will prove to be an asset in the development for both molecular breeding of ryegrass as well as comparative genetics and genomics within grass species.