title: Comparative genome analyses of Arabidopsis spp.: inferring chromosomal rearrangement events in the evolutionary history of A. thaliana.
abstract: Comparative genome analysis is a powerful tool that can facilitate the reconstruction of the evolutionary history of the genomes of modern-day species. The model plant Arabidopsis thaliana with its n = 5 genome is thought to be derived from an ancestral n = 8 genome. Pairwise comparative genome analyses of A. thaliana with polyploid and diploid Brassicaceae species have suggested that rapid genome evolution, manifested by chromosomal rearrangements and duplications, characterizes the polyploid, but not the diploid, lineages of this family. In this study, we constructed a low-density genetic linkage map of Arabidopsis lyrata ssp. lyrata (A. l. lyrata; n = 8, diploid), the closest known relative of A. thaliana (MRCA approximately 5 Mya), using A. thaliana-specific markers that resolve into the expected eight linkage groups. We then performed comparative Bayesian analyses using raw mapping data from this study and from a Capsella study to infer the number and nature of rearrangements that distinguish the n = 8 genomes of A. l. lyrata and Capsella from the n = 5 genome of A. thaliana. We conclude that there is strong statistical support in favor of the parsimony scenarios of 10 major chromosomal rearrangements separating these n = 8 genomes from A. thaliana. These chromosomal rearrangement events contribute to a rate of chromosomal evolution higher than previously reported in this lineage. We infer that at least seven of these events, common to both sets of data, are responsible for the change in karyotype and underlie genome reduction in A. thaliana.
authors.affiliation: Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Krithika
authors.initials: K
authors.lastname: Yogeeswaran
authors.forename: Amy
authors.initials: A
authors.lastname: Frary
authors.forename: Thomas L
authors.initials: TL
authors.lastname: York
authors.forename: Alison
authors.initials: A
authors.lastname: Amenta
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Lesser
authors.forename: June B
authors.initials: JB
authors.lastname: Nasrallah
authors.forename: Steven D
authors.initials: SD
authors.lastname: Tanksley
authors.forename: Mikhail E
authors.initials: ME
authors.lastname: Nasrallah
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D001499:Bayes Theorem; D029687:Capsella / Q000235:genetics; D007446:Chromosome Inversion; D032461:Chromosomes, Plant; D019143:Evolution, Molecular; D020440:Gene Duplication; D015321:Gene Rearrangement; D008040:Genetic Linkage; D005819:Genetic Markers; D018745:Genome, Plant; D020161:Physical Chromosome Mapping
chemical_list: D005819:Genetic Markers