NICKRENT, DANIEL L.1*, ALBERT BLARER2, YIN-LONG QIU2,3, DOUGLAS E. SOLTIS4, and MICHAEL ZANIS4. 1Department of Plant Biology and Center for Systematic Biology, Southern Illinois University, Carbondale, IL, USA 62901-6509; 2Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland; 3Department of Biology, University of Massachusetts, Amherst, MA 01003-5810; 4Department of Botany, Washington State University, Pullman, WA 99165-4236. - Paleoherb Status of Hydnoraceae Supported by Multigene Analyses.
Utilization of molecular phylogenetic information over the past decade
has resulted in clarification of the position of most angiosperm
orders, as demonstrated by the classification produced by the
Angiosperm Phylogeny Group. A group of 11 families was listed at the
beginning of the APG classification because "they belong neither
in any of the phylogenetically basal orders at the beginning nor in
the monocots or eudicots." The phylogenetic positions of most of
these families (e.g. Amborellaceae, Nymphaeaceae, Winteraceae, etc.)
have since been clarified, however, the positions of two holoparasitic
families, Hydnoraceae and Rafflesiaceae, have remained enigmatic. To
address the question of phylogenetic position of Hydnoraceae, nuclear
SSU and LSU rDNA and mitochondrial atp1 and matR
sequences were obtained for Hydnora and Prosopanche.
These sequences were used in a combined analysis that included the
above four genes as well as chloroplast rbcL and atp
(these plastid genes are mising in Hydnoraceae and were hence coded as
missing). Three data sets were analyzed using maximum parsimony: 1) 3
genes/461 taxa; 2) 5 genes/77 taxa; and 3) 6 genes/38 taxa. All of
these analyses support the monophyly of Hydnoraceae and the
association of that clade with the "paleoherb" families
Aristolochiaceae and Lactoridaceae. These results suggests that either
Aristolochiaceae are paraphyletic or that Hydnoraceae should be
included (along with Lactoridaceae) in a more broadly defined family
Aristolochiaceae. In contrast to most traditional classifications,
molecular phylogenetic analyses do not suggest a close relationship
between Hydnoraceae and Rafflesiaceae s. lat.
Key words: Aristolochiaceae, Hydnora, molecular phylogeny, paleoherb, Prosopanche