Systematics Section / ASPT
Friend, Sheena A. , Quandt, Dietmar , Volpe, Daniel S. , Hilu, Khidir W. .
Stystematics of Arachis (Fabaceae): information from morphology versus DNA seqeucnes.
The South American genus Arachis L. (Fabaceae) contains approximately 80 species, including the economically important peanut crop (Arachis hypogaea L.). Based on morphology and geographic distribution, the genus Arachis has been divided into nine sections: Arachis, Caulorrhizae, Erectoides, Extranervosae, Heteranthae, Procumbentes, Rhizomatosae, Trierectoides, and Triseminatae. Previous studies examining evolutionary relationships either were limited by species/section representation or were based on molecular data that did not lend themselves well to phylogenetic analysis. Thus, the systematics of the genus remains in need of an in-depth study. We are using sequence information from plastid trnT-trnF and nuclear internal transcribed spacer (ITS) regions to examine phylogenetic relationships among 37 species from all nine sections. The data were analyzed in PAUP* using Maximum Parsimony with species from Chapmannia and Stylosanthes as outgroup taxa. Differences in topologies between the trnT-trnF and ITS trees were notable and may reflect potential ancient hybridization. The strict consensus based on the combined data sets shows a grade of three lineages and a major terminal clade. Section Extranervosae emerged as sister to remaining sections of the genus Arachis. Most of the currently recognized sections did not appear monophyletic. Species of section Arachis, the largest section in the genus, formed two clades. One contains mostly the A genome species while the other is comprised of the aneuploid species which is sister to a linage of B and D genome species. Strong bootstrap support was evident for the monophyly of the genus, the monophyly of the aneuploid and their sister group relationship to the B and D genome species, and the polyphyly of some of the sections.
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1 - Virginia Tech, Department of Biological Sciences, 2119 Derring Hall
, Blacksburg, VA, 24061-0406, United States
2 - Dresden University of Technology, Institute of Botany, Plant Phylogenetics & Phylogenomics Group, Dresden, D-01062, Germany
3 - Virginia Tech, Biological Sciences, Blacksburg, Virginia, 24061, USA
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM