Identification of Zanthoxyli Radix and its adulterants using ITS2 barcoding / 中草药

ABSTRACT

Objective: ITS2 barcoding was used to discriminate Zanthoxyli Radix and its adulterants to ensure the quality and clinical safety of this Chinese materia medica. Methods: The internal transcribed spacer 2 (ITS2) regions were amplified and sequenced bi-directionally. Then the obtained sequences were assembled using the CodonCode Aligner. The ITS2 regions were obtained using the hidden Markov model (HMM)-based annotation methods. The genetic distances of the ITS2 regions were computed in accordance with the kimura 2-parameter (K2P) model and Neighbor-joining (NJ) phylogenetic trees were constructed using MEGA5.0. Results: The length of ITS2 sequences of the plants in Zanthoxyli Radix and its adulterants were between 224 and 227 bp. Their mean intraspecific genetic distance (K2P distance) was lower than their mean interspecific genetic distance with the adulterants. The NJ trees showed that the roots of Zanthoxyli Radix could be easily distinguished from its adulterants. Conclusion: ITS2 barcode could be used to identify the roots of Zanthoxyli Radix and its adulterants effectively, and provide the important molecular evidence for the authentication of germplasm resources.