Systematics Section / ASPT
Dastidar, Sayantani , Zhengqiu, Cai , Peñaflor, Cynthia , Kuehl, Jennifer V. , Boore, Jeffrey L. , Jansen, Robert K. .
Phylogenetic analysis of Chloranthus and Dioscorea based on whole chloroplast genome sequences.
CHLORANTHACEAE is a family of approximately five genera and seventy species distributed in the tropics and subtropics. The placement of Chloranthus among basal angiosperms has been controversial. Some previous phylogenies based on analyses of one or few gene sequences placed Chloranthus outside of magnolids, as sister to rest of the angiosperms followed by Ceratophyllaceae and monocots. However, support for this placement was weak. Other molecular phylogenetic studies positioned Chloranthaceae sister to monocots and magnolids but this placement was also weakly supported. In order to resolve the placement of Chloranthaceae, we have sequenced whole chloroplast genomes of Chloranthus and Dioscorea, a basal monocot. Dioscoreaceae is a family of approximately seven genera and 750 species with a primarily pantropical distribution. The chloroplast genomes of both Chloranthus and Dioscorea have identical gene order and content as most other angiosperms, including tobacco. All shared protein coding and rRNA genes were extracted from these genomes aligned with these same genes from 40 other available angiosperm chloroplast genomes. Alignment of the genes was performed by developing a semi-automated procedure, which for protein-coding genes includes an initial alignment of amino acid sequences followed by manual adjustments. This amino acid alignment is then used to constrain the nucleotide alignment. Preliminary parsimony analyses of amino acid sequences place Dioscorea near the base of monocots. Chloranthus is nested within the magnolids, although bootstrap support for this placement is only moderate. More rigorous phylogenetic analyses using both parsimony and likelihood methods and alignments of nucleotide sequences are in progress and will be presented. These analyses should provide valuable new data for the placement of Chloranthaceae and the position of Dioscoreaceae.[c.e.:srb]
Log in to add this item to your schedule
1 - University of Texas Austin, Section of Integrative Biology, 1 University Station, A6700, Austin, Texas, 78712-7640, USA
2 - Brigham Young University, Department of Integrative Biology, 401 Widtsoe Building, Provo, Utah, 84602, USA
3 - DOE Joint Genome Institute, Department of Evolutionary Genomics, 2800 Mitchell Drive, Walnut Creek, California, 94598, USA
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM