Molecular Identification of Chinese Materia Medica and Its Adulterants Using ITS2 and psbA-trnH Barcodes: A Case Study on Rhizoma Menispermi

Rhizoma Menispermi, derived from the rhizoma of Menispermum dauricum DC., is one of the most popular Chinese medicines. However Rhizoma Menispermi is often illegally mixed with other species in the herbal market, including Aristolochia mollissimae Hance, which is toxic to the kidneys and potentially carcinogenic. The use of DNA barcoding to authenticate herbs has improved the management and safety of traditional medicines. In this paper, 49 samples belonging to five species, including 34 samples of M. dauricum, from different locations and herb markets in China were collected and identified using DNA barcoding. The sequences of all 34 samples of Rhizoma Menispermi are highly consistent, with only one site variation in internal transcribed spacer 2 (ITS2) of nuclear ribosomal DNA and no variations in the psbA-trnH region. The intra-specific genetic distance is much smaller than inter-specific one. Phylogenetic analysis shows that both sequences allow the successful identification of all species. Nearest distance and BLAST1 methods for the ITS2 and psbA-trnH regions indicate 100% identification efficiency. Our research shows that DNA barcoding can effectively distinguish Rhizoma Menispermi from its adulterants from both commercial and original samples, which provides a new and reliable way to monitor comThese two authors contributed equally to this work. Corresponding author.