Systematics Section / ASPT
Nickrent, Daniel , Anderson, Frank , Der, Joshua .
Phylogenetic analyses identify the photosynthetic relatives of Cynomorium and Balanophoraceae.
Recent molecular phylogenetic work has helped place several nonphotosynthetic holoparasites such as Hydnoraceae and Rafflesiales within the overall angiosperm phylogeny. Two other holoparasitic groups, Cynomoriaceae and Balanophoraceae, are currently listed as "taxa of uncertain position" in APG2. Debate exists as to whether Cynomorium is a member of Balanophoraceae or whether it should be segregated into its own family. In either case, all classifications accept a close relationship between the two groups. We used nuclear, chloroplast, and mitochondrial gene sequence data, analyzed with maximum parsimony and Bayesian inference methods, to determine whether Balanophoraceae and Cynomoriaceae are related to one another and where they fit in the overall angiosperm phylogeny. Analysis of a four gene data set strongly supported the independent origin of these two families. Thus, the morphological features thought to link Cynomorium and some members of Balanophoraceae must be interpreted as convergent. Cynomorium is placed in Saxifragales with strong support whereas Balanophoraceae appear related to Santalales. The latter result is surprising because any morphological similarities have usually been assumed to be convergent. A five gene data set was used to determine the position of Cynomorium within Saxifragales. The shortest MP trees contained a clade composed of Cynomorium and Crassulaceae, however, this relationship did not receive high support. To pinpoint the exact sister group of Balanophoraceae within Santalales, additional sequence data is required. Cynomorium species are extensively used in herbal medicines and recent phytochemical and biomedical research has demonstrated physiological activity. Because all material is being collected from wild populations and because cultivation methods are currently unknown, overexploitation has resulted in localized extinctions. Identification of the photosynthetic relatives of Cynomorium would initiate work to determine whether these plants also contain compounds of biomedical interest, thus relieving pressure on the more sensitive parasitic species.
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1 - Southern Illinois University, Department of Plant Biology, 1125 Lincoln Drive, Carbondale, Illinois, 62901-6509, USA
2 - Southern Illinois University, Department of Zoology, Carbondale, Illinois, 62901, USA
Presentation Type: Oral Paper
Date: Tuesday, August 16th, 2005
Time: 11:45 AM