title: Legume genome evolution viewed through the Medicago truncatula and Lotus japonicus genomes.
abstract: Genome sequencing of the model legumes, Medicago truncatula and Lotus japonicus, provides an opportunity for large-scale sequence-based comparison of two genomes in the same plant family. Here we report synteny comparisons between these species, including details about chromosome relationships, large-scale synteny blocks, microsynteny within blocks, and genome regions lacking clear correspondence. The Lotus and Medicago genomes share a minimum of 10 large-scale synteny blocks, each with substantial collinearity and frequently extending the length of whole chromosome arms. The proportion of genes syntenic and collinear within each synteny block is relatively homogeneous. Medicago-Lotus comparisons also indicate similar and largely homogeneous gene densities, although gene-containing regions in Mt occupy 20-30% more space than Lj counterparts, primarily because of larger numbers of Mt retrotransposons. Because the interpretation of genome comparisons is complicated by large-scale genome duplications, we describe synteny, synonymous substitutions and phylogenetic analyses to identify and date a probable whole-genome duplication event. There is no direct evidence for any recent large-scale genome duplication in either Medicago or Lotus but instead a duplication predating speciation. Phylogenetic comparisons place this duplication within the Rosid I clade, clearly after the split between legumes and Salicaceae (poplar).
authors.affiliation: Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108, USA.
authors.forename: Steven B
authors.initials: SB
authors.lastname: Cannon
authors.forename: Lieven
authors.initials: L
authors.lastname: Sterck
authors.forename: Stephane
authors.initials: S
authors.lastname: Rombauts
authors.forename: Shusei
authors.initials: S
authors.lastname: Sato
authors.forename: Foo
authors.initials: F
authors.lastname: Cheung
authors.forename: Jérôme
authors.initials: J
authors.lastname: Gouzy
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Wang
authors.forename: Joann
authors.initials: J
authors.lastname: Mudge
authors.forename: Jayprakash
authors.initials: J
authors.lastname: Vasdewani
authors.forename: Thomas
authors.initials: T
authors.lastname: Schiex
authors.forename: Thomas
authors.initials: T
authors.lastname: Scheix
authors.forename: Manuel
authors.initials: M
authors.lastname: Spannagl
authors.forename: Erin
authors.initials: E
authors.lastname: Monaghan
authors.forename: Christine
authors.initials: C
authors.lastname: Nicholson
authors.forename: Sean J
authors.initials: SJ
authors.lastname: Humphray
authors.forename: Heiko
authors.initials: H
authors.lastname: Schoof
authors.forename: Klaus F X
authors.initials: KF
authors.lastname: Mayer
authors.forename: Jane
authors.initials: J
authors.lastname: Rogers
authors.forename: Francis
authors.initials: F
authors.lastname: Quétier
authors.forename: Giles E
authors.initials: GE
authors.lastname: Oldroyd
authors.forename: Frédéric
authors.initials: F
authors.lastname: Debellé
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Cook
authors.forename: Ernest F
authors.initials: EF
authors.lastname: Retzel
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Roe
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Town
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.forename: Yves
authors.initials: Y
authors.lastname: Van de Peer
authors.forename: Nevin D
authors.initials: ND
authors.lastname: Young
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics; D020440:Gene Duplication; D017343:Genes, Plant / Q000235:genetics; D018745:Genome, Plant / Q000235:genetics*; D000070116:Lotus / Q000235:genetics*; D046913:Medicago truncatula / Q000235:genetics*; D010802:Phylogeny; D026801:Synteny / Q000235:genetics