Co-PIs: Natalia Dudareva (Purdue University), Sarah O'Connor (John Innes Centre, UK), Douglas Soltis (University of Florida), Pamela Soltis (University of Florida)
The sixth largest flowering plant family, the Lamiaceae or mint family, is the source of many familiar mint and culinary flavors enjoyed by people worldwide. Many members of the mint family produce so-called secondary metabolites, which are by-products of plant chemistry that impart the familiar flavors of peppermint or spearmint in herbal teas or savory culinary seasoning from oregano, basil, lavender and other herbs. Human appreciation and consumption of these botanical compounds supports a growing agronomic industry, with the market for peppermint and spearmint oil alone worth over $200 million in 2011 (USDA); and yet how and why the underlying chemistry of these compounds evolved in the family is unknown. This project studies the chemical pathways required to synthesize flavor compounds using genome sequencing and by identifying all the relevant factors produced in each species. By comparing the resulting large datasets across family members, the project will clarify how such chemical processes evolved in plants. The interdisciplinary nature of the project requires the participation of experts in biochemistry, genomics, genetics and evolutionary biology. In turn, high school, undergraduate, and graduate students are trained at the frontiers of science by learning cutting edge genomics research that links directly to products of economic value. Through collaboration with the Michigan State University 4H Children's Garden and the Florida Museum of Natural History, the project offers informative displays and tours so the public can become citizen scientists as they learn about the evolution and underlying "flavor" chemistry of the familiar and much appreciated mint family.
The Lamiaceae represents a large family of angiosperms with a high degree of chemical diversity. The major subfamilies within the Lamiaceae, the Lamioideae and Nepetoideae, can be readily distinguished morphologically and also show qualitative and quantitative differences in the synthesis of two key specialized compounds, iridoids and volatile monoterpenoids. These compounds play an essential role in plant reproduction, defense, and signaling and are also the source of mint and other herbal flavors for human consumption. This project integrates genomic, metabolite, phylogenetic, and functional datasets to investigate the evolution of the monoterpene and iridoid biosynthetic pathways in the Lamiaceae. In the first phase, the transcriptomes and metabolomes of a phylogenetically diverse panel of 50 species will be generated and analyzed to identify a robust set of 14 species for focused study. In the second phase, full genome sequencing, expression, and metabolite levels will be conducted on the selected set, thus providing resources to (1) identify specific genes involved in monoterpene and iridoid biosynthesis, (2) elucidate key evolutionary events and mechanisms that led to the extant chemical diversity represented in the Lamiaceae, and (3) functionally test hypotheses about how variation in biosynthetic pathway genes contribute to chemical diversity. All resources from the project, including genome, transcriptome sequences and metabolite information will be publicly available through publications, the NCBI sequence archives, the Dryad Digital Repository and posted on a project website hosted at Michigan State University.
