title: Molecular adaptation in plant hemoglobin, a duplicated gene involved in plant-bacteria symbiosis.
abstract: The evolutionary history of the hemoglobin gene family in angiosperms is unusual in that it involves two mechanisms known for potentially generating molecular adaptation: gene duplication and among-species interaction. In plants able to achieve symbiosis with nitrogen-fixing bacteria, class 2 hemoglobin is expressed at high concentrations in nodules and appears to be a key factor for the achievement and regulation of the symbiotic exchange. In this study, we make use of codon models of DNA sequence evolution with the goal of determining the nature of the selective forces which have driven the evolution of this gene. Our results suggest that adaptive evolution occurred during the period of time following the duplication event (functional divergence) and that a change in the selective pressures arose in class 2 hemoglobin in relation to the acquisition of a symbiotic function.
authors.affiliation: CNRS UMR 5171--Génome, Populations, Interactions, Adaptation, Université Montpellier, 2--CC63, Place E Bataillon, 34095 Montpellier, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Guldner
authors.forename: Bernard
authors.initials: B
authors.lastname: Godelle
authors.forename: Nicolas
authors.initials: N
authors.lastname: Galtier
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D000595:Amino Acid Sequence; D001419:Bacteria / Q000235:genetics*; D003062:Codon / Q000235:genetics; D030561:Databases, Nucleic Acid; D019143:Evolution, Molecular; D020440:Gene Duplication; D006420:Hemeproteins / Q000235:genetics*; D016013:Likelihood Functions; D019684:Magnoliopsida / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D012641:Selection, Genetic; D013559:Symbiosis
chemical_list: D003062:Codon; D006420:Hemeproteins