title: Seed plant phylogeny: gnetophytes are derived conifers and a sister group to Pinaceae.
abstract: The phylogenetic position of gnetophytes has long been controversial. We sequenced parts of the genes coding for the largest subunit of nuclear RNA polymerase I, II, and III and combined these sequences with those of four chloroplast genes, two mitochondrial genes, and 18S rRNA genes to address this issue. Both maximum likelihood and maximum parsimony analyses of the sites not affected by high substitution levels strongly support a phylogeny where gymnosperms and angiosperms are monophyletic, where cycads are at the base of gymnosperm tree and are followed by ginkgos, and where gnetophytes are grouped within conifers as the sister group of pines. The evolution of several morphological and molecular characters of gnetophytes and conifers will therefore need to be reinterpreted.
authors.affiliation: Département de biologie et Centre de recherche avancée en génomique environnementale, Université d'Ottawa, Ottawa, Ont., Canada, K1N 6N5.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Hajibabaei
authors.forename: Junnan
authors.initials: J
authors.lastname: Xia
authors.forename: Guy
authors.initials: G
authors.lastname: Drouin
mesh_terms: D001483:Base Sequence; D003062:Codon / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D010802:Phylogeny; D028201:Pinaceae / Q000145:classification* / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics; D012639:Seeds / Q000145:classification / Q000235:genetics*; D014197:Trees / Q000235:genetics
chemical_list: D003062:Codon; D010940:Plant Proteins; D012321:DNA-Directed RNA Polymerases