GE, SONG1*, BARBARA SCHAAL2, AND DE-YUAN HONG1. 1Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China and 2Department of Biology, Washington University, St. Louis, Missouri 63130. - A preliminary phylogenetic analysis of the genus Adenophora (Campanulaceae)based on ITS sequence data.
Adenophora is a morphologically diverse genus of approximately
50 species of eastern Asia; the greatest diversity of
Adenophora species is found in China. Several taxonomic
treatments have proposed alternative subgeneric divisions within the
genus. In order to resolve the taxonomic ambiguities of
Adenophora, a molecular phylogenetic analysis was carried out
using sequences of the internal transcribed spacers (ITS) of nuclear
ribosomal DNA. Twenty-four species of Adenophora were sampled,
representing all of the previously recognized sections and
subsections. Three species of Campanula were used as outgroups.
Among the Adenophora species, the length of combined ITS-1 and
ITS-2 sequences ranged from 537 to 542 nucleotides; 5.7% of nucleotide
substitutions was phylogenetically informative. Parsimony analyses
suggested that none of the four sections recognized by Federov (1957)
and Tu (1993) is monophyletic. Hong(1983)'s two-section
classification, however, is generally concordant with the ITS
phylogeny except that A. triphylla of sect. Adenophora
is nested within sect. Microdiscus and A. trachelioides
of sect. Microdiscus forms a clade with species in sect.
Adenophora. Pairwise comparisons at unambiguously aligned sites
showed that the sequence divergence was relatively low among
Adenophora species with the values ranging from 0.0 to 3.9%. In
contrast, high sequence divergence was found among Adenophora
and Campanula species with the values ranging from 17.8 to
19.2%. These findings suggest a relatively recent origin of
Adenophora coupled with rapid morphological diversification
within the genus.
Key words: Adenophora, Campanulaceae, classification, ITS, phylogeny