title: New chloroplast microsatellite markers suitable for assessing genetic diversity of Lolium perenne and other related grass species.
abstract: OBJECTIVE
  Lolium perenne (perennial ryegrass) is the most important forage grass species of temperate regions. We have previously released the chloroplast genome sequence of L. perenne 'Cashel'. Here nine chloroplast microsatellite markers are published, which were designed based on knowledge about genetically variable regions within the L. perenne chloroplast genome. These markers were successfully used for characterizing the genetic diversity in Lolium and different grass species.
  
  
  METHODS
  Chloroplast genomes of 14 Poaceae taxa were screened for mononucleotide microsatellite repeat regions and primers designed for their amplification from nine loci. The potential of these markers to assess genetic diversity was evaluated on a set of 16 Irish and 15 European L. perenne ecotypes, nine L. perenne cultivars, other Lolium taxa and other grass species.
  
  
  RESULTS
  All analysed Poaceae chloroplast genomes contained more than 200 mononucleotide repeats (chloroplast simple sequence repeats, cpSSRs) of at least 7 bp in length, concentrated mainly in the large single copy region of the genome. Nucleotide composition varied considerably among subfamilies (with Pooideae biased towards poly A repeats). The nine new markers distinguish L. perenne from all non-Lolium taxa. TeaCpSSR28 was able to distinguish between all Lolium species and Lolium multiflorum due to an elongation of an A(8) mononucleotide repeat in L. multiflorum. TeaCpSSR31 detected a considerable degree of microsatellite length variation and single nucleotide polymorphism. TeaCpSSR27 revealed variation within some L. perenne accessions due to a 44-bp indel and was hence readily detected by simple agarose gel electrophoresis. Smaller insertion/deletion events or single nucleotide polymorphisms detected by these new markers could be visualized by polyacrylamide gel electrophoresis or DNA sequencing, respectively.
  
  
  CONCLUSIONS
  The new markers are a valuable tool for plant breeding companies, seed testing agencies and the wider scientific community due to their ability to monitor genetic diversity within breeding pools, to trace maternal inheritance and to distinguish closely related species.
authors.affiliation: Teagasc Crops Environment and Land Use Programme, Oak Park Research Centre, Carlow, Ireland. kerstin.diekmann@gmail.com
authors.forename: Kerstin
authors.initials: K
authors.lastname: Diekmann
authors.forename: Trevor R
authors.initials: TR
authors.lastname: Hodkinson
authors.forename: Susanne
authors.initials: S
authors.lastname: Barth
mesh_terms: D001947:Breeding; D002736:Chloroplasts / Q000235:genetics; D002874:Chromosome Mapping; D017931:DNA Primers / Q000235:genetics*; D018742:DNA, Chloroplast / Q000737:chemistry / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D056426:Genetic Loci; D014644:Genetic Variation / Q000235:genetics*; D054628:Genome, Chloroplast / Q000235:genetics; D006239:Haplotypes; D008129:Lolium / Q000235:genetics*; D018895:Microsatellite Repeats / Q000235:genetics*; D010802:Phylogeny; D006109:Poaceae / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers; D018742:DNA, Chloroplast