Essential oil plants in Mentha species have been valued historically for their medicinal, culinary, and fragrance properties. Despite the existence of several mint species and many cultivars, the U.S. Mint Oil Industry is based upon three sterile clones and their minor somatic variants. The narrow genetic base of these commercial varieties could endanger the stability of the mint industry if virulence of disease and/or large-scale fluctuations in weather occur. Extensive genetic diversity exists among other mint species and the U.S. mint industry is considering more effective future exploitation of this diversity to broaden the genetic base. Unfortunately, genetic diversity in mint is very poorly characterized, and the genetic relationships among known species and cultivars remain obscure. Here, we propose evaluating the utility of simple-sequence repeat (SSR or microsatellite) DNA fingerprinting techniques for answering the following questions: What are the relative levels of genetic diversity in extent mint species and cultivars? What are the genetic relationships among those species and cultivars? How well do SSR markers discriminate among closely related cultivars? ANTICIPATED RESULTS & POTENTIAL COMMERCIAL APPLICATIONS OF RESEARCH We expect to determine the abundance frequency of SSRs in Mentha species. Approximately 15 highly polymorphic SSR loci will be developed. Different cultivars will be identified. Genetic relationships among Mentha species/varieties will be estimated. These results offer distinct advantages over morphological and other types of data for identification and protection of varieties for mint industry. Information provided by the SSR markers will be used to design optimal procedures to mange germplasm collections for industry use. Future applications of SSR-based markers include genome mapping, gene tagging, and marker-assisted selection.
