title: EST data suggest that poplar is an ancient polyploid.
abstract: We analysed the publicly available expressed sequence tag (EST) collections for the genus Populus to examine whether evidence can be found for large-scale gene-duplication events in the evolutionary past of this genus. The ESTs were clustered into unigenes for each poplar species examined. Gene families were constructed for all proteins deduced from these unigenes, and K(S) dating was performed on all paralogs within a gene family. The fraction of paralogs was then plotted against the K(S) values, which resulted in a distribution reflecting the age of duplicated genes in poplar. Sufficient EST data were available for seven different poplar species spanning four of the six sections of the genus Populus. For all these species, there was evidence that a large-scale gene-duplication event had occurred. From our analysis it is clear that all poplar species have shared the same large-scale gene-duplication event, suggesting that this event must have occurred in the ancestor of poplar, or at least very early in the evolution of the Populus genus.
authors.affiliation: Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: Sterck
authors.forename: Stephane
authors.initials: S
authors.lastname: Rombauts
authors.forename: Stefan
authors.initials: S
authors.lastname: Jansson
authors.forename: Fredrik
authors.initials: F
authors.lastname: Sterky
authors.forename: Pierre
authors.initials: P
authors.lastname: Rouzé
authors.forename: Yves
authors.initials: Y
authors.lastname: Van de Peer
mesh_terms: D005075:Biological Evolution; D020224:Expressed Sequence Tags; D010802:Phylogeny; D011123:Polyploidy; D032107:Populus / Q000235:genetics*