INVESTIGADORES
SCATAGLINI Maria Amalia
artículos
Título:
Phylogenetic studies favor the unification of Pennisetum, Cenchrus and Odontelytrum: a nuclear, chloroplast and morphological combined analysis.
Autor/es:
CHEMISQUY, MARIA AMELIA; GIUSSANI, LILIANA MÓNICA; SCATAGLINI, MARÍA AMALIA; KELLOGG, ELIZABETH; MORRONE, OSVALDO
Revista:
ANNALS OF BOTANY
Editorial:
OXFORD UNIV PRESS
Referencias:
Año: 2010 vol. 106 p. 107 - 130
ISSN:
0305-7364
Resumen:
Twenty-five genera having sterile inflorescence branches were
recognized as the 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. 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 branch swapping. Branch support
was assessed with parsimony jackknifing. 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 among species through hybridization, its history most likely
reflects crossing relationships, rather than multiple independent appearances. Due to the consistency between our results and different phylogenetic hypotheses
(including morphological, developmental and multilocus approaches), and the
high support found for the PCO clade, also including the type species of the
three genera, we propose unification of Pennisetum, 1 Cenchrus and
Odontelytrum. Species of Pennisetum and Odontelytrum are
here transferred into Cenchrus, which has priority. A total of 66 new combinations are listed herein.