title: Topological incongruence between nuclear and chloroplast DNA trees suggesting hybridization in the urophyllum group of the genus Fagopyrum (Polygonaceae).
abstract: We performed phylogenetic analyses of Fagopyrum species in the urophyllum group based on nucleotide sequences of two nuclear genes, FLORICAULA/LEAFY (FLO/LFY) and AGAMOUS (AG), and three segments of chloroplast DNA (cpDNA), rbcL-accD, trnK intron, and trnC-rpoB spacer. The FLO/LFY and AG sequences turned out to be phylogenetically more informative at the intrageneric level than the cpDNA sequences. Congruence among these gene trees, inferred by a maximum-likelihood (ML) method, demonstrated that topologies were partially incongruent between the nuclear and chloroplast DNA phylogenies. The nuclear DNA sequence data supported a monophyletic relation of F. statice, F. gilesii, and F. jinshaense, whereas the former two species formed another monophyletic relation with the F. capillatum-F. gracilipes-F. gracilipedoides-F. rubifolium clade excluding F. jinshaense in the synthetic cpDNA phylogeny. In addition, two divergent sequences of FLO/LFY were found in F. rubifolium (tetraploid). One of these was sister to F. gracilipedoides and another was sister to F. statice, and a monophyletic relation of these two genes was rejected by a bootstrap analysis. These results suggest that hybridization may have occurred during diversification of Fagopyrum species in the urophyllum group, and that F. rubifolium is possibly allotetraploid species.
authors.affiliation: Department of Biosystems Science, School of Advanced Studies, The Graduate University for Advanced Studies. nishimoto_yuriko@soken.ac.jp
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Nishimoto
authors.forename: Ohmi
authors.initials: O
authors.lastname: Ohnishi
authors.forename: Masami
authors.initials: M
authors.lastname: Hasegawa
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics*; D002736:Chloroplasts / Q000235:genetics*; D018742:DNA, Chloroplast; D006824:Hybridization, Genetic; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D019664:Polygonaceae / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D018742:DNA, Chloroplast; C083654:FLO protein, Antirrhinum majus; C074747:LFY protein, Arabidopsis; D010940:Plant Proteins; D014157:Transcription Factors