Development and Use of Novel Subtracted Diversity Array for Fingerprinting Medicinal Plants

The global market for medicinal plants and their products is currently $60 billion and growing at estimated rate of 6.4% per annum. The surge in demand has unfortunately resulted in increased cases of contamination, either through misidentification or purposeful adulteration. The classic species identification techniques using morphological features, chemical profiles, and PCR-based methods have a number of limitations. We set out to develop one tool that can be utilized to fingerprint all medicinal plants. We developed a novel technique called Subtracted Diversity Array that is based on subtraction of genomic DNA pool of one group of species from another. Initially, an angiosperm-specific microarray was developed which was capable of differentiating most of the flowering plants to family level and species level. We further refined this array by developing clade specific array for Asterids and Rosids species. These arrays are capable of identifying closely related species and species with large genomes. Recently, we have extended this technique to enable identification of chemotypes of two commercially important herbs, Echinacea and Salvia. The Subtracted Diversity Array is capable of identifying species that are not used in its construction and more importantly identifying novel genes and DNA fragments that would otherwise take years of PCR work to discover.