A preliminary molecular phylogeny of Pennisetum and Cenchrus (Poaceae-Paniceae) based on the trnL-F, rpl16 chloroplast markers

DONADÍO S, L M GIUSSANI, EA KELLOGG, FO ZULOAGA, O MORRONE

TAXON

International Association for Plant Taxonomy

Lugar: Vienna Austria; Año: 2009 p. 392 - 404

0040-0262

Pennisetum (80 a 140 species) and Cenchrus (16 a 22 species) are closely related genera of Paniceae, both distributedin tropical and sub-tropical regions. The distinction between Pennisetum and Cenchrus is not clearlydefined, and currently no comprehensive taxonomic treatment is available for either genus. Chloroplast DNAsequence data (rpl16, trnL-F region) were analyzed to test their monophyly, species relationships, and infragenericclassifications. Phylogenetic analyses of individual genomic regions, and a combined dataset, includingindel-coded information, were performed under parsimony and Bayesian inference. Selected geographical,chromosomal and morphological characters were mapped onto the phylogeny to investigate evolutionary trends.Our results support a monophyletic bristle clade and the close relationship between Pennisetum and Cenchrus.Excluding Pennisetum lanatum, Pennisetum is paraphyletic because Cenchrus is nested within it. SectionsPennisetum and Gymnotrix are polyphyletic. Our molecular phylogenetic results show a close relationshipamong the domesticated species P. glaucum, P. purpureum, P. squamulatum, P. nervosum, and P. sieberianum,suggesting the potential use of these species in crop improvement. The Pennisetum-Cenchrus clade shows anindependent reduction (x = 5, 7, 8) or duplication (x = 17) of the basic chromosome number from the ancestralx = 9. American Pennisetum and Cenchrus species appear to have originated from Old World species morethan once. A core group of American species of Cenchrus with a basic chromosome number of x = 17 andretrorsely barbed bristles could be restricted to Cenchrus s.str.