DNA Barcoding the Major Medicinal Plants of the World.

DNA barcoding is emerging as one of the many important tools on the modern taxonomists’ work bench that will function as an accurate genetic species identifier for academic and applied purposes.  Discovery of a DNA barcode for land plants has been limited by intrinsically lower rates of sequence evolution in plant genomes than in animals.  This low rate has complicated the trade-off in finding a locus that is universal and readily sequenced yet has sufficiently high sequence divergence at the species-level.  We have shown that a combination of the rbcL coding gene and the trnH-psbA non-coding spacer of the plastid genome provides the necessary universality and species discrimination necessary for an effective plant barcode.  We have now applied this two-locus barcode to a data set of 689 species of vascular plants (in 103 families) listed as the major medicinal plants in World Economic Plants: A Standard Reference.  This set of plant DNA barcodes can now be used to screen the content and quality of natural plant products employed as medicines and herbal supplements in both commercial and non-commercial applications.