Panax species identification with the assistance of DNA data

Panax species have been used as medicinal plants in China and adjacent areas, but the difficulty in wild species identification based on morphological characters prevents the exploration and utilization of these resources. To assist in identifying the species, three plastid intergenic spacers and four nuclear genes of 129 samples from 20 different localities were sequenced to conduct the clustering analyses. P. stipuleanatus and P. notoginseng were relatively easy to be distinguished from other species based on morphological characters and clustering results. Three samples collected from Laos grouped together with those collected from Jinping (China), and they were all identified as P. vietnamensis. However, the fourth one LW4 had closer genetic relationship to P. notoginseng than to P. vietnamensis. Although they were morphologically different in petiolule length, the samples preliminarily identified as P. zingiberensis grouped together in the clustering analyses, and the results of STRUCTURE analysis suggested that samples collected from Zhenyuan shared some genetic component with P. vietnamensis. As for the samples identified as P. japonicus and P. wangianus, there were so many variations in leaves, rhizomes and rootstocks that it was difficult to differentiate them from each other. Molecular data also showed that these taxa were genetically admixed and the samples identified as P. wangianus could be classified into P. japonicus. The nucleotide diversity results indicated that the wild relatives had more substantial genetic diversity compared to P. notoginseng.