Abstract
M.Sc. (Botany)
The market and public demand for medicinal plants over the past few decades has
increased dramatically with more than 1 000 plant species actively traded for
medicinal purposes throughout South Africa. Intensive harvesting of wild material is
now acknowledged as a serious threat to biodiversity in this country. Also the
substitution of a valuable commodity (medicinal plant) by a cheaper alternative (other
plant species), either inadvertently due to misidentification, or deliberately to cheat
consumers, raises some serious concerns as these adulterants may not be as effective
or may even be toxic and cause harm to consumers. To add to the problem many
species are either traded as dried leaf, root, bark products, or extracts and their
identification becomes problematic. Therefore, DNA barcoding can help to provide a
rapid and accurate identification tool for medicinal plants. In the current study I
targeted the most commonly used medicinal plants in South Africa and produced a set
of barcodes for fast and easy DNA-based species identification (rbcLa & matK). I
tested the efficiency of core barcodes in the identification of medicinal plants using
four main analyses, in the R package Spider 1.1-1. Here the extent of specific genetic
divergence, DNA barcoding gap, BLAST test, and the ability to discriminate between
species were assessed. Overall, the matK region was found to be a more useful tool
for the species identification of medicinal plants in South Africa.