ABSTRACT
Objective:To develop a simple and accurate method for molecular authentication of Panax ginseng and P. quinquefolius.Method:The mitochondrial cox Ⅱ sequences of P. ginseng and P. quinquefolius were amplified by polymerase chain reaction（PCR）with universal primers. PCR products of the two species were sequenced in both directions, and sequence alignments were conducted for intron length polymorphisms exploitation. Multiplex PCR was established for the identification of P. ginseng and P. quinquefolius with their specific primers，which were designed respectively based on their insertion sequences. And the limit of detection of the multiplex PCR was also determined.Result:The insertion/deletion sequences were exploited in mitochondrial cox Ⅱ. Under the established multiplex PCR assay，P. ginseng generated a 729 bp specific band, while P. quinquefolius yielded a 141 bp specific amplicon，and the mixture of the two species yielded both 729 bp and 141 bp fragments. The established multiplex PCR assay could detect 0.1% of intentional adulteration of P. quinquefolius into P. ginseng, with down to 0.001 ng of genomic DNA.Conclusion:The established multiplex PCR assay can accurately identify P. ginseng and P. quinquefolius from different sources, without the optimization of reaction system and the introduction of additional mismatches，so as to provide a new molecular marker method for identifying botanical origin of P. ginseng and P. quinquefolius.