Maryam Moudi - Faculty of Science, University of Birjand, Birjand, South Khorasan, Iran.
Rusea Go - Department of Biology, Faculty of Science, University Putra Malaysia & Institute of Tropical Forestry & Forest Products, University Putra Malaysia

The present study focused on the molecular phylogeny of the four sections (Aporum, Crumenata, Strongyle, and Bolbidium) of genus Dendrobium SW. (Orchidaceae) based upon low copy nuclear gene, Xanthine Dehydrogenase (Xdh) sequences using maximum parsimony (MP), maximum likelihood (ML) and Bayesian (BI) methods. Single and low copy nuclear genes have been increasingly used in phylogenetic reconstruction because they contain large amounts of genetic information and are biparentally inherited. Classifications based on morphological characters have not been able to clearly divide these four sections and neither do they support their monophyletic origins. Therefore, detailed analysis using molecular data is required to ascertain their status. This study includes ۲۰ species of genus Dendrobium and ۲ species from genus Bulbophyllum (section Sestochilus) as outgroup taxa. According to the results, the aligned sequences consisted of ۷۳۳ nucleotide characters of which ۱۳۱characters were parsimony informative.  The analysis revealed that the nuclear genes can be reliable marker for the phylogenetic study of genus Dendrobium. The results suggested that the four sections are probably best considered as one section instead of four and based on the International code of Botanical Nomenclature (ICBN) rules can be named as section Aporum for this new classification.

Dendrobium, Orchidaceae, low copy nuclear gene, Xdh, monophyly, phylogeney