Neves, Susana S. , Swire-Clark, Ginger , Hilu, Khidir W. , Baird, Wm. Vance .
Phylogeny of Eleusine (Poaceae: Chloridoideae) based on nuclear and plastid DNA sequence analyses.
Species and genome evolution in the primarily African genus Eleusine remain controversial. Nuclear rRNA ITS and plastid trnT-trnF sequences were used to investigate phylogenetic relationships among diploid and polyploid taxa (eight species; x = 8, 9 and 10). Datasets were analyzed using parsimony, distance and likelihood-based methods, including Bayesian. Congruence was examined using character and topological measures. Significant data heterogeneity was detected. However, little conflict existed in the topological substructure measures for triplets and quartets, and resolution and clade support increased in combined analysis. Data incongruence may result from noise and insufficient information in the slower-evolving trnT-trnF. Monophyly of Eleusine is strongly supported, but basal relationships in the genus remain uncertain. There is good support for a CAIK clade (E. coracana, E. indica, and E. kigeziensis), with E. tristachya (the only non-African species) as its sister group. Two putative ITS homeologues (A and B loci) were identified in the allotetraploid E. coracana; the B locus sequence was not found in the remaining seven species. Eleusine coracana and its putative "A" genome donor, the diploid E. indica, are confirmed close allies, but sequence data contradicts the hypothesis that E. floccifolia is its second genome donor. The "B" genome donor remains unidentified and may be extinct.
1 - Clemson University, Horticulture, Poole Agric. Center, Clemson, South Carolina, 29634-0319, U.S.A.
2 - Virginia Polytechnic Institute and State University, Department of Biology, Blacksburg, Virginia, 24061, USA
3 - Universidade Nova de Lisboa, Instituto de Tecnologia Química e Biológica, Oeiras, 2781-901, Portugal
Presentation Type: Paper
Location: Peruvian (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 4:15 PM