DUVALL, MELVIN R.1, JEFFREY D. NOLL2*, and ALEXANDRA H. MINN1. 1Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois 60115-2861; 2Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota 57007-0595. - Phylogenetics of Paniceae (Poaceae).
The phylogenetics of Poaceae is generally well-studied with the
exception of the large and variable Paniceae within which intergeneric
relationships are uncertain. Paniceae demonstrate unique variability
of photosynthetic physiology and anatomy including both non-kranz and
kranz species and all subtypes of the latter. This variability
suggests both hypotheses of independent origin and reversals (e.g.
from kranz to non-kranz). These hypotheses can be tested by
phylogenetic analysis of independent molecular characters. The
molecular phylogeny of 60 species of Paniceae was explored using
sequences from the grass-specific insert found in the plastid locus
rpoC2. Phylogenetic analyses confirmed some long recognized
alliances in Paniceae, some recent molecular phylogenetic results, and
suggested new relationships as well. Broadly, Paniceae were found to
be paraphyletic with Andropogoneae, Panicum was found to be
polyphyletic, and Oplismenus hirtellus was resolved as the
sister group to the remaining ingroup species. A particularly well
supported clade in the rpoC2 tree included four genera with
non-kranz species and three with distinctively keeled paleas. As
previously suggested, the PEP-ck subtype arose once within Paniceae.
All clades with non-kranz species had kranz ancestors or sister taxa
suggesting repeated loss of the kranz syndrome. Other correlations
between photosynthetic physiology and molecular phylogeny await
Key words: kranz, molecular phylogenetics, non-kranz, Paniceae, Poaceae rpoC2 insert