title: Extensive synteny conservation of holocentric chromosomes in Lepidoptera despite high rates of local genome rearrangements.
abstract: The recent assembly of the silkworm Bombyx mori genome with 432 Mb on 28 holocentric chromosomes has become a reference in the genomic analysis of the very diverse Order of Lepidoptera. We sequenced BACs from two major pests, the noctuid moths Helicoverpa armigera and Spodoptera frugiperda, corresponding to 15 regions distributed on 11 B. mori chromosomes, each BAC/region being anchored by known orthologous gene(s) to analyze syntenic relationships and genome rearrangements among the three species. Nearly 300 genes and numerous transposable elements were identified, with long interspersed nuclear elements and terminal inverted repeats the most abundant transposable element classes. There was a high degree of synteny conservation between B. mori and the two noctuid species. Conserved syntenic blocks of identified genes were very small, however, approximately 1.3 genes per block between B. mori and the two noctuid species and 2.0 genes per block between S. frugiperda and H. armigera. This corresponds to approximately two chromosome breaks per Mb DNA per My. This is a much higher evolution rate than among species of the Drosophila genus and may be related to the holocentric nature of the lepidopteran genomes. We report a large cluster of eight members of the aminopeptidase N gene family that we estimate to have been present since the Jurassic. In contrast, several clusters of cytochrome P450 genes showed multiple lineage-specific duplication events, in particular in the lepidopteran CYP9A subfamily. Our study highlights the value of the silkworm genome as a reference in lepidopteran comparative genomics.
authors.affiliation: Unité Mixte de Recherche 1231, Institut National de la Recherche Agronomique, Université Montpellier II, 34095 Montpellier, France.
authors.forename: E
authors.initials: E
authors.lastname: d'Alençon
authors.forename: H
authors.initials: H
authors.lastname: Sezutsu
authors.forename: F
authors.initials: F
authors.lastname: Legeai
authors.forename: E
authors.initials: E
authors.lastname: Permal
authors.forename: S
authors.initials: S
authors.lastname: Bernard-Samain
authors.forename: S
authors.initials: S
authors.lastname: Gimenez
authors.forename: C
authors.initials: C
authors.lastname: Gagneur
authors.forename: F
authors.initials: F
authors.lastname: Cousserans
authors.forename: M
authors.initials: M
authors.lastname: Shimomura
authors.forename: A
authors.initials: A
authors.lastname: Brun-Barale
authors.forename: T
authors.initials: T
authors.lastname: Flutre
authors.forename: A
authors.initials: A
authors.lastname: Couloux
authors.forename: P
authors.initials: P
authors.lastname: East
authors.forename: K
authors.initials: K
authors.lastname: Gordon
authors.forename: K
authors.initials: K
authors.lastname: Mita
authors.forename: H
authors.initials: H
authors.lastname: Quesneville
authors.forename: P
authors.initials: P
authors.lastname: Fournier
authors.forename: R
authors.initials: R
authors.lastname: Feyereisen
mesh_terms: D000818:Animals; D001483:Base Sequence; D018826:CD13 Antigens / Q000235:genetics; D002875:Chromosomes / Q000235:genetics*; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D016000:Cluster Analysis; D019143:Evolution, Molecular; D017344:Genes, Insect / Q000235:genetics*; D023281:Genomics / Q000379:methods; D008969:Molecular Sequence Data; D009036:Moths / Q000235:genetics*; D005810:Multigene Family / Q000235:genetics; D017422:Sequence Analysis, DNA; D026801:Synteny / Q000235:genetics*
chemical_list: D018826:CD13 Antigens
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