A one-tube assay for four Hypericum species – PlantID

The benefits of DNA-based identification methods for medicinal plant products have been shown – negligible amounts of starting material, high resolving power, increased taxonomic specificity, and fast results (1). However, the simultaneous detection of multiple species in one sample has not until now been possible. We report the design of PlantID for St John's Wort (SJW) (Hypericum perforatum L.); a technique capable of detecting both the target species (SJW) and a number of likely adulterants in one sample using a multiplex PCR approach coupled to high resolution DNA fragment analysis.

The method is based on the creation of fluorescently labelled amplicons of different lengths which can be resolved via capillary electrophoresis. Each amplicon confirms the presence one of four Hypericum species; H. androsaemum L., H. athoumBoiss. & Orph., H. ascyron Siebold ex Blume and H. perforatum L. These amplicons are produced in a multiplex PCR, with all four reactions occurring simultaneously.

The target species for design used in this study represent a worst case scenario, with only a few base differences between the ITS regions for each target. It is likely that a selection of target medicinal plants would not be as closely related, and would therefore have significantly more sequence differences. This would dramatically increase the number of species which could be detected in one assay.

This technique has the power to both confirm the presence of expected plant material and detect adulterant material in one reaction. The method of design could be replicated for any other medicinal plant, and its problem adulterants.

Keywords: Molecular Identification, Hypericum perforatum, PlantID

References: 1 Howard C et al. (2009) Planta Med 75: 864–869.