Systematics Section / ASPT
Hansen, Debra , Zhengqiu, Cai , Boore, Jeffrey L. , Kuehl, Jennifer V. , Jansen, Robert K. .
Complete chloroplast genome sequences of Illicium (Schisandraceae) and Buxus (Buxaceae): Genome organization and implications for phylogeny of angiosperms.
AS part of a larger study of angiosperm phylogeny, we have sequenced the chloroplast genomes of Anise (Illicium, Schisandraceae) and Boxwood (Buxus, Buxaceae). Illicium is one of the basal angiosperms in the Austrobaileyales. Our data shows Illicium to have a gene order similar to tobacco, but with an inverted repeat (IR) 10 kb smaller than tobacco. Many chloroplast genomes have expanded IR regions but in most instances these expansions are not large (> 1kb). Significant contractions of the IR are rare with only two known examples in angiosperms, Apiaceae and Cuscuta. Neither Amborella nor Nymphaea show a reduced IR, and no other member of Austrobaileyales (Austrobaileyaceae, Schisandraceae and Trimeniaceae) has been sequenced. Therefore, it is not yet known if this reduction is a synapomorphy for Austrobaileyales or is unique to Illicium. Buxus is an early-diverging eudicot. Although several studies have confirmed its placement between basal angiosperms and core eudicots, they disagree on the relationship between Buxaceae and the closely-related Trochodendraceae. Floral development changed greatly between the basal angiosperms and core eudicots, and one hypothesis is that the putative AP3 duplication may have happened between the divergence of Buxus and Trochodendron. Previous multiple-gene studies have not resolved the Buxus/Trochodendron relationship, and clarity at this level is needed to further infer the evolution of floral development in this important transitional stage of angiosperm history. We will use sequences for 80 shared chloroplast genes, combined with other available chloroplast genome sequences of angiosperms, to place Buxus and Illicium in the angiosperm tree.
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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
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM