In order to develop DNA barcoding system for identifying herbal medicine, Chinese government initiated International S&T Cooperation Project and National High-tech R&D Program (863 Program). Professor Shilin Chen as a PI with his team has selected and compared different candidate barcodes from nuclear, mitochondria and plastid genomes for near ten years.
Herbal medicines, which have a long and well documented history of use in the prevention and treatment of various diseases, continue to gain global influence in modern medical and health services. However, giventhe large number and variety of medicinal plants (the consensus is more than 70000 different species), the ability to reliably distinguish them from their close relatives, inferior substitutes, adulterants, and counterfeits presents a challenge, risking patient safety and herbal efficacy.DNA barcoding, a technique aiming at detecting species-specific differences in a short region of DNA,provides a new powerful tool towards addressing this problem. A preliminary system for DNA barcoding herbal materialshas been established based on a two-locus combination of ITS2+psbA–trnH barcodes.
DNA barcoding is not restricted by morphological characteristics and physiological conditions and allows species authentication without specialist taxonomic knowledge. The method is also standardized to specific DNA barcodes and universal primers, which is a favorable for building databases and establishing a universal standard for identification. DNA barcoding can achieve rapid, accurate, and automated identification of species from a diverse range and quality of raw materials. This addresses the difficulties involved in classifying herbal materials and promises to fuel a taxonomic renaissance in herbal identification.
In order to make DNA barcoding information universally and publically accessible, online databases need to be compiled and made available online. The Canadian Centre for DNA Barcoding established the first online DNA barcoding database: the Barcode of Life Data System (http://www.boldsystems.org). This database currently documents barcoding results using matK and rbcL for plants, ITS for fungi and COI for animals. Projects can be created within the Barcode of Life Data System, which are made publically available. Two additional databases, IdIt-ITS2 (http://its2-plantidit.dnsalias.org) for plants and animals, and PTIGS-IdIt (http://psba-trnh-plantidit.dnsalias.org) for plants, have been developed to facilitate the application of ITS2 and psbA–trnH barcodes. Organism-specific databases are also available, including the Lepidoptera Barcode of Life (http://www.lepbarcoding.org) and Fish Barcode of Life (http://www.fishbol.org). In 2010, Lou et al. developed a DNA barcoding database for medicinal materials (http://www.cuhk.edu.hk/icm/mmdbd.htm). This Medicinal Materials DNA Barcode Database accepts all plastid DNA regions and nuclear ITS results for medicinal plant materials.
More recently, a universal, publically available DNA barcoding system for identifying herbal materials has been established based on the ITS2 and psbA–trnH barcodes. The system has been used for identifying herbal materials, and the principles and methods have been approved for incorporation into supplement 3 of the Chinese Pharmacopoeia(2010 edition). Furthermore, an online DNA barcoding database for herbal materials has been constructed (http://www.tcmbarcode.cn), which provides a species identification module for herbal materials. In this database, ITS2 and psbA–trnH are selected as the core and supplementary DNA barcodes, respectively, for herbal materials. In order to correctly distinguish medicinal species, this database also contains barcoding data for their adulterants, substitutes and closely related species.