title: Genome size reduction through illegitimate recombination counteracts genome expansion in Arabidopsis.
abstract: Genome size varies greatly across angiosperms. It is well documented that, in addition to polyploidization, retrotransposon amplification has been a major cause of genome expansion. The lack of evidence for counterbalancing mechanisms that curtail unlimited genome growth has made many of us wonder whether angiosperms have a "one-way ticket to genomic obesity." We have therefore investigated an angiosperm with a well-characterized and notably small genome, Arabidopsis thaliana, for evidence of genomic DNA loss. Our results indicate that illegitimate recombination is the driving force behind genome size decrease in Arabidopsis, removing at least fivefold more DNA than unequal homologous recombination. The presence of highly degraded retroelements also suggests that retrotransposon amplification has not been confined to the last 4 million years, as is indicated by the dating of intact retroelements.
authors.affiliation: John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom. Katrien.devos@bbsrc.ac.uk
authors.forename: Katrien M
authors.initials: KM
authors.lastname: Devos
authors.forename: James K M
authors.initials: JK
authors.lastname: Brown
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Bennetzen
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D018745:Genome, Plant; D011995:Recombination, Genetic / Q000235:genetics*; D018626:Retroelements / Q000235:genetics
chemical_list: D018626:Retroelements