A linkage map of meadow fescue (Festuca pratensis Huds.) and comparative mapping with other Poaceae species

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Abstract
A genetic linkage map has been constructed for meadow fescue (Festuca pratensis Huds.) (2n=2x=14) using a full-sib family of a cross between a genotype from a Norwegian population (HF2) and a genotype from a Yugoslavian cultivar (B14). The two-way pseudo-testcross procedure has been used to develop separate maps for each parent, as well as a combined map. A total number of 550 loci have been mapped using homologous and heterologous RFLPs, AFLPs, isozymes and SSRs. The combined map consists of 466 markers, has a total length of 658.8 cM with an average marker density of 1.4 cM/marker. A high degree of orthology and colinearity was observed between meadow fescue and the Triticeae genome(s) for all linkage groups, and the individual linkage groups were designated 1F–7F in accordance with the orthologous Triticeae chromosomes. As expected, the meadow fescue linkage groups were highly orthologous and co-linear with Lolium, and with oat, maize and sorghum, generally in the same manner as the Triticeae chromosomes. It was shown that the evolutionary 4AL/5AL translocation, which characterises some of the Triticeae species, is not present in the meadow fescue genome. A putative insertion of a segment orthologous to Triticeae 2 at the top of 6F, similar to the rearrangement found in the wheat B and the rye R genome, was also observed. In addition, chromosome 4F is completely orthologous to rice chromosome 3 in contrast to the Triticeae where this rice chromosome is distributed over homoeologous group 4 and 5 chromosomes. The meadow fescue genome thus has a more ancestral configuration than any of the Triticeae genomes. The extended meadow fescue map reported here provides the opportunity for beneficial cross-species transfer of genetic knowledge, particularly from the complete genome sequence of rice.