@ARTICLE{TreeBASE2Ref18742, author = {M. Amelia Chemisquy and Liliana M. Giussani and M. Amalia Scataglini and Elizabeth A. Kellogg and Osvaldo Morrone}, title = {Phylogenetic studies favour the unification of Pennisetum, Cenchrus and Odontelytrum (Poaceae): a nuclear, plastid and morphological combined analysis, and nomenclatural}, year = {2010}, keywords = {}, doi = {}, url = {}, pmid = {}, journal = {Annals of Botany}, volume = {}, number = {}, pages = {}, abstract = {?Backgrounds and aims: Twenty-five genera having sterile inflorescence branches were recognized as the monophyletic bristle clade within the x = 9 Paniceae (Panicoideae). Within the bristle clade, taxonomic circumscription of Cenchrus (20-25 species), Pennisetum (80-140) and the monotypic Odontelytrum is still unclear. Several criteria have been applied to characterize Cenchrus and Pennisetum, but none of these has been satisfactory since the diagnostic characters, such as fusion of bristles in the inflorescences, present continuous variation. ?Methods: We present a phylogenetic analysis based on morphological, plastid (trnL-F, ndhF) and nuclear (knotted) data for a representative species sampling of the genera. All analyses were conducted under parsimony, using heuristic searches with TBR swapping. Branch support was assessed with parsimony jackknifing. ?Key results: Based on plastid and morphological data, Pennisetum, Cenchrus and Odontelytrum were supported as a monophyletic group: the PCO clade. Only one section of Pennisetum (Brevivalvula) was supported as monophyletic. The position of P. lanatum differed among data partitions, although the combined plastid and morphology and nuclear analyses found this species to be included in the PCO clade. The basic chromosome number x = 9 was found to be plesiomorphic, and x = 5, 7, 8, 10 and 17 were derived states. The nuclear phylogenetic analysis revealed a reticulate pattern of relationships among Pennisetum and Cenchrus, suggesting that there are at least three different genomes. Because apomixis can be transferred to different species through hybridization, its history most likely reflects crossing relationships, rather than its appearence independently several times. ?Conclusions: Due to the consistency among our results, studies that considered morphology, development and multilocus approaches, and the high support found for the PCO clade, we propose to unify Cenchrus, Pennisetum and Odontelytrum. Species of Pennisetum and Odontelytrum are here transferred into Cenchrus, which has priority at the rank of genus. A total of 66 new combinations are listed herein. } }

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