title: Germplasm dynamics: the role of ecotypic diversity in shaping the patterns of genetic variation in Lolium perenne.
abstract: Perennial ryegrass (Lolium perenne) is the most widely grown temperate grass species globally. Intensive plant breeding in ryegrass compared to many other crops species is a relatively recent exercise (last 100 years) and provides an interesting experimental system to trace the extent, impact and trajectory of undomesticated ecotypic variation represented in modern ryegrass cultivars. To explore germplasm dynamics in Lolium perenne, 2199 SNPs were genotyped in 716 ecotypes sampled from 90 European locations together with 249 cultivars representing 33 forage/amenity accessions. In addition three pseudo-cross mapping populations (450 individual recombinants) were genotyped to create a consensus genetic linkage map. Multivariate analyses revealed strong differentiation between cultivars with a small proportion of the ecotypic variation captured in improved cultivars. Ryegrass cultivars generated as part of a recurrent selection programme (RSP) are strongly associated with a small number of geographically localised Italian ecotypes which were among the founders of the RSP. Changes in haplotype frequency revealed signatures of selection in genes putatively involved in water-soluble carbohydrate (WSC) accumulation (a trait selected in the RSP). Retrospective analysis of germplasm in breeding programmes (germplasm dynamics) provides an experimental framework for the identification of candidate genes for novel traits such as WSC accumulation in ryegrass.
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion, Wales. SY23 3EE.
authors.forename: T
authors.initials: T
authors.lastname: Blackmore
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion, Wales. SY23 3EE.
authors.forename: D
authors.initials: D
authors.lastname: Thorogood
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion, Wales. SY23 3EE.
authors.forename: L
authors.initials: L
authors.lastname: Skøt
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion, Wales. SY23 3EE.
authors.forename: R
authors.initials: R
authors.lastname: McMahon
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion, Wales. SY23 3EE.
authors.forename: W
authors.initials: W
authors.lastname: Powell
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion, Wales. SY23 3EE.
authors.forename: M
authors.initials: M
authors.lastname: Hegarty
mesh_terms: D060146:Ecotype; D006239:Haplotypes; D008129:Lolium / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide