PlantID – DNA-based identification of multiple medicinal plants in complex mixtures

The ITS regions of several Hypericum species were analysed to identify the most divergent regions and PCR primers were designed to anneal specifically to these regions in the different Hypericum species. Candidate primers were selected such that the amplicon produced by each species-specific reaction differed in size. The use of fluorescently labelled primers enabled these products to be resolved by capillary electrophoresis.Four closely related Hypericum species were detected simultaneously and independently in one reaction. Each species could be identified individually and in any combination. The introduction of three more closely related species to the test had no effect on the results. Highly processed commercial plant material was identified, despite the potential complications of DNA degradation in such samples.This technique can detect the presence of an expected plant material and adulterant materials in one reaction. The method could be simply applied to other medicinal plants and their problem adulterants.The quality of Chinese medicines (CM) has been questioned because of “continuing evidence of an international trade in herbal remedies made to an unreliable standard” [1-3], and there is increasing international demand for regulation of phytomedicines and definitive quality standards [4,5]. In the European Union (EU), the Traditional Herbal Medicines Directive (Directive 2004/24/EC) regulates medicinal plant products for human use, and all medicinal plant products must now hold a Traditional Herbal Registration (THR) certified by a logo on all packaging. To gain a THR, many factors must be certified, such as the identification and authentication of the medicinal plant material upstream of manufacturing and processing. This is currently achieved by morphological and chemical methods, both of which are time-consuming and cost-intensive [6].DNA-based methods are a preferred alternative, because they are more efficient, less expensive and time-consuming, requ