PHYLOGENETIC ANALYSIS AMONG FOUR SECTIONS OF THE GENUS DENDROBIUM SW. (ORCHIDACEAE) BASED ON LOW COPY NUCLEAR GENE (XDH) SEQUENCES IN PENINSULAR MALAYSIA

The present study focused on the molecular phylogeny of the four sections (aporum, crumenata, strongyle, and bolbidium) of the 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 20 species of genus dendrobium and 2 species from genus bulbophyllum (section sestochilus) as outgroup taxa. according to the results, the aligned sequences consisted of 733 nucleotide characters of which 131characters 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.