Development of Molecular Markers for the authentication of Zanthoxyli Pericarpium by the analysis of rDNA-ITS DNA barcode regions

Abstract

Objectives : Due to the morphological similarity of the pericarp and description of multi-species in National Pharmacopoeia of Korea and China, the Zanthoxylum Pericarpium is difficult to authenticate adulterant in species levels. Therefore, we introduced the sequence analysis of DNA barcode and identification of single nucleotide polymorphism(SNP) to establish a reliable tool for the distinction of Zanthoxylum Pericarpium from its adulterants. Methods : To analyze DNA barcode region, genomic DNA was extracted from twenty-four specimens of authentic Zanthoxylum species and inauthentic adulterant and the individual internal transcribed spacer regions (rDNA-ITS and ITS2) of nuclear ribosomal RNA gene were amplified using ITS1, ITS2-S2F, and ITS4 primer. For identification of species-specific sequences, a comparative analysis was performed using entire DNA barcode sequences. Results : In comparison of four Zanthoxylum ITS2 sequences, we identified 16, 4, 6, and 4 distinct species-specific nucleotides enough to distinguish Z. schinifolium, Z. bungeanum, Z. piperitum, and Z. simulans, respectively. The sequence differences were available genetic marker to discriminate four species. Futhermore, phylogenetic relationship revealed a clear classification between different Zanthoxylum species showing 4 different clusters. These results indicated that comparative analysis of ITS2 DNA barcode was an useful genetic marker to authenticate Zanthoxylum Pericarpium in species levels. Conclusions : The marker nucleotides, enough to distinguish Z. schinifolium, Z. piperitum, Z. bungeanum, and Z. simulans, were obtained at 30 SNP marker nucleotides from ITS2 sequences. These differences could be used to authenticate official Zanthoxylum Pericarpium from its adulterants as well as discriminating each four species.