Molecular phylogeny of Coelogyne (Epidendroideae; Orchidaceae) based on plastid RFLPS, matK, and nuclear ribosomal ITS sequences: evidence for polyphyly

摘要

To evaluate the monophyly of Coelogyne (Epidendroideae; Orchidaceae) and reveal sectional relationships and relations to allied genera in subtribe Coelogyninae, we collected PCR (polymerase chain reaction) amplified restriction fragment length polymorphisms (RFLPs) from 11 plastid regions for 42 taxa (28 Coelogyne species and 14 representatives of other genera) and three outgroups from Bletiinae and Thuniinae. We also sequenced a large portion of the plastid trnK intron (mostly matK) and the nuclear ribosomal DNA internal transcribed spacers ITS1 and ITS2 (including the 5.8S gene). Separate phylogenetic analyses on each data set using maximum parsimony produced mainly congruent (except for the position of Panisea) but weakly supported clades. Parsimony analysis of the combined data clearly identified three main clades in Coelogyninae. Whereas Coelogyninae are monophyletic, Coelogyne is polyphyletic, with species falling into at least two well-supported clades. The utility of morphological characters used in previous classifications was explored by reconstructing character state evolution on one of the four molecular trees. Lip base and petal shape were homoplasious, whereas ovary indumentum and flower number were congruent with well-supported groups. The implications of our results for the classification of Coelogyne are discussed, and a reorganization of the genus by including Neogyna and Pholidota and removing several species is proposed.