The immune system of any higher organism needs to respond vigorously to microorganisms that pose a threat while simultaneously ignoring harmless ones. Biologically speaking, this is a significant balancing act. To achieve this degree of specificity, plants have evolved a special immune response, called effector-triggered immunity, that allows the plant to detect harmful proteins and to react both defensively and appropriately; as is true with humans, an overly vigorous immune response can be harmful to a plant's own health. To ensure an optimal immune response, the plant Arabidopsis thaliana has evolved a type of "quality control" mechanism, a key component of which is a novel protein, called SRFR1, that is conserved in animals as well as plants. This project will determine whether SRFR1 dampens effector-triggered immune responses by physically binding to positive immune regulators. Through a combination of genetic, genomic, and biochemical techniques, the investigators will determine how SRFR1 works and, specifically, how SRFR1 is induced to switch protein binding partners in order to regulate different steps in the plant's immune response. The project's outcome includes a better understanding of how plant immune signaling is kept in check and, specifically, how a single protein can regulate a whole signaling pathway through direct and dynamic interactions with other proteins. This knowledge may aid efforts to produce crops with robust resistance to pathogens while minimizing negative side effects on yield. This project's broader impacts include the education and training of a graduate student and a post-doctoral researcher. The project also will be used in a larger effort by the University of Missouri to engage freshmen undergraduate students in research experiences in plant biology. With mechanistic knowledge of how plants fight off disease, society will be better equipped to boost plants' natural immune responses, which would benefit sustainable agriculture, biomass production, and the environment.