In their evolutionary battle with viruses, plants have developed mechanisms to prevent infection, while viruses have countered by evolving proteins that can overcome these plant defenses. This project will examine how one of these virus proteins from the Poleroviruses, designated P0, interacts with the plant Nicotiana glutinosa, a relative of tobacco. P0 overcomes RNA interference (RNAi), a plant defense mechanism that acts against viruses with RNA genomes, like the Poleroviruses, by eliminating a key RNAi enzyme, Argonaute 1 (AGO1). Nicotiana glutinosa has evolved a resistance (R) protein that causes infected cells to die when it encounters P0 from some Poleroviruses, preventing spread of the virus infection within the plant. The investigators will seek to discover the gene for this R protein using transposon tagging, a method that locates a gene by disrupting it through insertion of a foreign piece of DNA called a transposon. The project will also investigate how P0 functions by creating mutants to determine protein regions crucial for activity, and by purifying P0 for structural analysis. This research will establish a new model system that could provide insight applicable to R protein function against the broad spectrum of pathogens and parasites that challenge modern agriculture, while providing opportunities for master's and undergraduate students to engage in molecular biology research. Undergraduate students conducting research on this project will be recruited from California State University, Fullerton, one of the nation's leading institutions for graduating Hispanic students with bachelor's degrees. Beyond serving the goals of integrating science and education for undergraduate and graduate students at California State University, Fullerton, this project will have broader impacts through the engagement of local high school students in summer research experiences that will enhance their science education and promote the pursuit of careers in science.