Phylogenetic analysis based on 18S rRNA gene and matK gene sequences of Panax vietnamensis and five related species

Panax vietnamensis was discovered recently in Vietnam. Its bamboo-like rhiz omes, called Vietnamese Ginseng, have attracted considerable attention beca use of their specific pharmacological activities. In order to define the ta xonomic position of this new species and include it in the molecular authen tication of Ginseng drugs, the 18S ribosomal RNA gene and matK gene sequenc es of P. vietnamensis were determined and compared with those of its relate d taxa, P. japonicus var. major and P. pseudo-ginseng subsp. himalaicus, be sides previously reported P. ginseng, P. japonicus and P. quinquefolius. Th e 18S rRNA gene sequences were found to be 1809 bps in length. The sequence of P. vietnamensis was identical to that of P. quinquefolius, and presente d one base substitution from those of both P. japonicus var, major and P. p seudo-ginseng subsp. himalaicus. The matk gene sequences of 6 taxa were fou nd to be 1509 bps in length. The sequence of P. vietnamensis differed from those of P. japonicus var, major, P. pseudo-ginseng subsp. himalaicus, P. g inseng, P. japonicus and P. quinquefolius at 4, 5, 9, 9 and 10 nucleotide p ositions, respectively. The phylogenetic tree reconstructed by the combined 18S rRNA-matK gene analysis using the maximum parsimony method showed that P. vietnamensis was sympatric with other Panax species and had a close rel ationship with P. japonicus var. major and P. pseudo-ginseng subsp. himalai cus.