title: The role of transposable element clusters in genome evolution and loss of synteny in the rice blast fungus Magnaporthe oryzae.
abstract: BACKGROUND
  Transposable elements are abundant in the genomes of many filamentous fungi, and have been implicated as major contributors to genome rearrangements and as sources of genetic variation. Analyses of fungal genomes have also revealed that transposable elements are largely confined to distinct clusters within the genome. Their impact on fungal genome evolution is not well understood. Using the recently available genome sequence of the plant pathogenic fungus Magnaporthe oryzae, combined with additional bacterial artificial chromosome clone sequences, we performed a detailed analysis of the distribution of transposable elements, syntenic blocks, and other features of chromosome 7.
  
  
  RESULTS
  We found significant levels of conserved synteny between chromosome 7 and the genomes of other filamentous fungi, despite more than 200 million years of divergent evolution. Transposable elements are largely restricted to three clusters located in chromosomal segments that lack conserved synteny. In contradiction to popular evolutionary models and observations from other model organism genomes, we found a positive correlation between recombination rate and the distribution of transposable element clusters on chromosome 7. In addition, the transposable element clusters are marked by more frequent gene duplications, and genes within the clusters have greater sequence diversity to orthologous genes from other fungi.
  
  
  CONCLUSIONS
  Together, these data suggest that transposable elements have a profound impact on the M. oryzae genome by creating localized segments with increased rates of chromosomal rearrangements, gene duplications and gene evolution.
authors.affiliation: Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA. mthon@tamu.edu
authors.forename: Michael R
authors.initials: MR
authors.lastname: Thon
authors.forename: Huaqin
authors.initials: H
authors.lastname: Pan
authors.forename: Stephen
authors.initials: S
authors.lastname: Diener
authors.forename: John
authors.initials: J
authors.lastname: Papalas
authors.forename: Audrey
authors.initials: A
authors.lastname: Taro
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Mitchell
authors.forename: Ralph A
authors.initials: RA
authors.lastname: Dean
mesh_terms: D001483:Base Sequence; D015825:Chromosomes, Fungal; D017124:Conserved Sequence; D004251:DNA Transposable Elements; D004271:DNA, Fungal / Q000235:genetics; D019143:Evolution, Molecular; D020440:Gene Duplication; D016681:Genome, Fungal; D020082:Magnaporthe / Q000235:genetics*; D005810:Multigene Family; D012275:Oryza / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D004251:DNA Transposable Elements; D004271:DNA, Fungal