Phylogeny and classification of the bamboos (Poaceae: Bambusoideae) based on molecular and morphological data

Chloroplast ndhF gene sequences and morphological and leaf anatomical characters were analyzed separately and as combined data sets to reconstruct the phylogeny of subfamily Bambusoideae. The analyses further confirmed that the monophyletic bambusoid clade consists of only two monophyletic lineages: the woody bamboos, and the herbaceous olyroid bamboos. Buergersiochloa was resolved as the basal lineage in the herbaceous olyroids, whereas Pariana/Eremitis was sister to the rest of the olyroids. The woody bamboos were divided into two main groups: temperate woody bamboos and tropical woody bamboos; and the tropical clade was further subdivided along geographic lines into the Old World woody bamboos and the New World woody bamboos. Puelia was resolved as the most basal lineage of the 'higher grasses' and thus was excluded from the bambusoid clade. Streptogyneae joined the oryzoids, including the Oryzeae and Ehrharteae, to form another separate monophyletic clade. The results of this study indicate that the current Bambusoideae is not acceptable phylogenetically. Therefore a new circumscription of the Bambusoideae with two tribes is proposed in which only members of the bambusoid clade are included; the woody bamboos are classifed as one tribe, the Bambuseae, and the herbaceous olyroid bamboos are classified in another tribe, the Olyreae.; In order to provide additional resolution of phylogenetic relationships within the bambusoid clade, an attempt to generate nuclear ribosomal ITS sequence data of bamboos was made. However, polymerase chain reaction amplification (PCR) led to the recovery of fungal instead of bamboo sequences. Phylogenetic analyses based on the 5.8S sequences indicated that all the sequences belonged to basidiomycetes and that none was an ascomycete. A diverse assemblage of basidiomycetes was isolated from different bamboo hosts and various fungi coexisted in the same host plant. No evidence showed that closely related fungi were associated with closely related bamboo hosts. True bamboo ITS sequences were obtained only after leaf surface sterilization before DNA isolation. This study highlights the possibility of inadvertent PCR amplification of "contaminating DNA" in molecular phylogenetic studies. The results also indicate that a close ecological association between epiphytic basidiomycetes and bamboo leaves may exist, but further study is needed.