Grant: Discovery Grants Program - Individual

Plant secondary metabolites are compounds that mediate interactions between plants and their environment. My research program explores (1) pathways involved in secondary metabolism and (2) the ecological roles of secondary metabolites. For example the study of suberin formation allows exploration of the regulation of metabolic pathways and the partitioning of carbon between different potential metabolic endpoints - critical knowledge required to make informed decisions about modifying plant metabolism for improved nutrition or enhanced disease resistance. Suberin is a tissue-specific cell wall modification deposited in a developmental manner as well as in response to wounding and plays a critical role in water retention and protection against pathogens. Using chemical, biochemical and metabolomic approaches my research group has identified key enzymatic steps unique to the biosynthesis of suberin. This proposal describes my intent to isolate and characterize the genes encoding these steps. While molecular biology tools are new to my research program, their use represents a logical progression in our approach to study suberin biosynthesis. From an ecological point of view, plants use secondary metabolites to prevent pathogens from causing disease. Plant pathogens, however, can use plant-derived secondary metabolites as cues to locate potential hosts. Ginsenosides are triterpenoid saponins with mild fungitoxic properties that leach into the soil surrounding ginseng roots. We have shown that Pythium irregulare secretes an enzyme (glycosidase) that selectively degrades specific ginsenosides to a common intermediate (ginsenoside F2), which is then taken up by the organism, making ginsenosides host recognition factors for this organism. We will characterize the enzymes involved and mechanism by which P. irregulare utilizes ginsenosides to find host roots. My research objectives provide tools to study the regulation of secondary metabolism and the functional roles of secondary metabolites. The results will contribute to our fundamental understanding of plant metabolism: essential knowledge upon which more practical applications can be built.