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Genetics Section

Haberle, Rosemarie C. [1], Jansen, Robert K. [1], Boore, Jeffrey L. [2], Kuehl, Jennifer V. [2].

Comparative chloroplast genomics of Campanulales s.l.: phylogenomic implications and chloroplast genome evolution.

Chloroplast genome structural rearrangements are relatively rare in land plants. It is likely that mutational events such as the generation of repeat elements or double stranded break repair predispose a chloroplast genome to such major changes. Clues for how those changes may have occurred are likely obscured over time at the sequence level, but within a recently derived group with multiple rearrangements, it may be possible to find convincing evidence of specific events. The Campanulaceae and close relatives within the clade loosely termed the Campanulales are known for rearranged chloroplast genomes. We are sequencing the complete chloroplast genomes of 9 taxa representing all major lineages in the families Campanulaceae, Nemacladaceae, and Cyphiaceae. We have completed sequencing three members of the Campanulaceae (Trachelium, Platycodon, Wahlenbergia), as well as Pseudonemacladus (Nemacladaceae) and a species of Cyphia (Cyphiaceae). Sequencing of other representatives of the clade are now close to completion. We have identified many additional structural changes within this clade not previously identified through mapping. Some of these rearrangements are shared across the group and substantiate the monophyly of the "Campanulales", but within the Campanulaceae, several divide the family into distinct clades or represent autapomorphies. Detailed analyses of these genomes show that they all contain numerous repeat sequences, many associated with endpoints of blocks of rearranged genes. These genomes have many more repeats than all other sequenced angiosperm chloroplast genomes. We are characterizing and comparing rearrangement locations in these taxa to pinpoint causes of rearrangement. The Campanulales s.l. offers a model system for studying mechanisms of chloroplast genome evolution. Complete chloroplast genome sequencing of members of this clade may address several critical questions regarding the phylogenetic relationships of these relatives as well as elucidate mechanisms of how chloroplast genomes can change.


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1 - University of Texas Austin, Section of Integrative Biology, 1 University Station, A6700, Austin, Texas, 78712-7640, USA
2 - DOE Joint Genome Institute, Department of Evolutionary Genomics, 2800 Mitchell Drive, Walnut Creek, California, 94598, USA

Keywords:
Chloroplast Genomics, Genome Evolution, Plastids.

Presentation Type: Poster
Session: 33-52
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM
Abstract ID:337


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