Phylogeny of Saururaceae based on mitochondrial matR gene sequence data.

DNA sequences of matR gene from three species of Saururaceae and the selected outgroups, Chloranthus holostegius and Zippelia begoniaefolia, are reported. All DNA sequences of six species in four genera of Saururaceae and the two outgroups are analyzed on PAUP 4.0 8b to reconstruct the phylogeny. A single matR gene tree is generated from parsimony, distance, and likelihood analyses, respectively. The three trees with the same topology are slightly different in bootstrapping support for some clades. The result indicates that Saururaceae is monophyletic. Anemopsis is sister to Houttuynia, and the two genera form the first diverging lineage of the family. The sister group relationship between Saururus and Gymnotheca is also supported by a relatively high bootstrap value. The result is different from all the former phylogenetic opinions on Saururaceae based on morphology, but it is supported by the evolution of flower-bract stalk in Saururaceae. In addition, some characteristics of the matR gene are analyzed. The MatR gene is a relatively better tool to reconstruct the molecular clock because the base substitution bias greatly decreases in the gene.