Phylogenetic relationships of the genus Taxus inferred from chloroplast intergenic spacer and nuclear coding DNA

A cladistic analysis of the medicinal plant Taxus, using the sequences of one chloroplast (trnS-trnQ spacer) and three nuclear taxadiene synthase (TS), 10-deacetylbaccatin III-10 beta-O-acetyltransferase (DBAT), and 18S rDNA) molecular markers, was carried out by distance, parsimony, likelihood, and Bayesian methods. Three of the four New World species (T brevifolia, T floridana and T globosa) form a well-supported clade, whereas T canadensis initially branches-appearing distantly related to both Old World taxa and New World species. In Asia, Taxus chinensis, T mairei, T sumatrana and T wallichiana cluster together and are sister to a clade containing T baccata and T contorta. Taxus yunnanensis is more closely related to T wallichiana than to four other Taxus species in our study from China; T contorta is closer to the Euro-Mediterranean T baccata than to the Asian species. This study provides a genetic method for authentication of economically important Taxus species and proposes a robust phylogenetic hypothesis for the genus. Using trnS-trnQ spacer sequences, we were able to distinguish T mairei from all other species of Taxus.