Authentication of commercial processed Glehniae Radix (Beishashen) by DNA barcodes

Background: The radix of Glehnia littoralis Fr. Schmidt ex Miq. (Beishashen), is often misidentified and adultered in Chinese medicine. Its seven common adulterants include Chuanminshen violaceum Sheh et Shan (Chuanmingshen), Changium smyrnioides Wolff (Mingdangshen), Sphallerocarpus gracilis (Bess.) K.-Pol. (Miguoqin), Adenophora polyantha Nakai (Shishashen), Silene tatarinowii Regel (Shishengyingzicao), Adenophora tetraphylla (Thunb.) Fisch (Lunyeshashen) and Adenophora stricta Miq. (Shashen). This study aims to evaluate the feasibility of the second internal transcribed spacer (ITS2) DNA barcoding to discriminate between Glehniae Radix and its common adulterants. Methods: In this study, we collected 46 samples of G. littoralis and 59 samples of its seven common adulterants. Genomic DNA sequences were extracted from samples, including original plants and commercially processed crude drugs. The ITS2 of the ribosomal DNA sequences were amplified and sequenced bi-directionally. The sequences were assembled by CodonCode Aligner 3.5.7. The descriptive data analysis was conducted and neighbor-joining (NJ) phylogenetic tree was constructed by MEGA 5.0 in accordance with the kimura 2 -parameter (K2P) model. The identification efficiency was evaluated based on the BLAST1 methods. The ITS2 secondary structures were predicted and compared between Glehniae Radix and its adulterants by the ITS2 database. Results: As the 46 ITS2 sequences of G. littoralis were identical to each other, the identification efficiency of the ITS2 region was 100 %. A NJ tree based on the ITS2 sequences, and the predicted secondary structures of ITS2, distinguished Glehniae Radix from its adulterants. Conclusion: DNA barcoding based on ITS2 distinguished commercial processed Glehniae Radix from common herbal adulterants.