A phylogenetic analysis of Prunus and the Amygdaloideae (Rosaceae) using ITS sequences of nuclear ribosomal DNA

The economically important plum or cherry genus (Prunus) and the subfamily Amygdaloideae of the Rosaceae have a controversial taxonomic history due to the lack of a phylogenetic framework. Phylogenetic analysis using the ITS sequences of nuclear ribosomal DNA (nrDNA) was conducted to construct the evolutionary history and evaluate the historical classifications of Prunus and the Amygdaloideae. The analyses suggest two major groups within the Amygdaloideae: (1) Prunus s.l. (sensu lato) and Maddenia, and (2) Exochorda, Oemleria, and Prinsepia. The ITS phylogeny supports the recent treatment of including Exochorda (formerly in the Spiraeoideae) in the Amygdaloideae. Maddenia is found to be nested within Prunus s.l. in the parsimony and distance analyses, but basal to Prunus s.l. in the maximum likelihood analysis. Within Prunus, two major groups are recognizable: (1) the Amygdalus–Prunus group, and (2) the Cerasus–Laurocerasus–Padus group. The clades in the ITS phylogeny are not congruent with most subgeneric groups in the widely used classification of Prunus by Rehder. A broadly defined Prunus is supported.