Internal transcribed spacer 2 (ITS2) barcodes: A useful tool for identifying Chinese Zanthoxylum

The genus Zanthoxylum in the Rutaceae family of trees and shrubs has a long history of domestication and cultivation in Asia for both economic and medicinal purposes. However, many Zanthoxylum species are morphologically similar and are easily confused. This often leads to false authentication of source materials and confusion in herbal markets, hindering their safe utilization and genetic resource conservation. DNA barcoding is a promising tool for identifying plant taxa.

We used three candidate DNA barcoding regions (ITS2, ETS, and trnH-psbA) to identify 69 accessions representing 13 Chinese Zanthoxylum species. The discriminatory capabilities of these regions were evaluated in terms of PCR amplification success, intra- and interspecific divergence, DNA barcoding gaps, and identification efficiency using the BLAST and tree-building methods.

ITS2 proved the most useful for discriminating Chinese Zanthoxylum species, with a correct identification rate of 100%, and this region also exhibited significantly higher intra- and interspecific divergence.

Phylogenetic analysis confirmed that ITS2 has a powerful discriminatory ability both at and below the species level. We confirmed that ITS2 is a powerful barcoding region for identifying Chinese Zanthoxylum species, and will be useful for analyzing and managing Chinese Zanthoxylum germplasm collections.