EVERY INDIVIDUAL HUMAN, ANIMAL AND PLANT SERVES AS HOST FOR A DIVERSITY OF MICROBES THAT TOGETHER COMPRISE ITS MICROBIOME. WHILE THE MICROBIOME IS COMPRISED MOSTLY OF ORGANISMS THAT USUALLY DO NO HARM TO THE HOST, OR EVEN BENEFIT THE HOST, THE MICROBIOME ALSO ALMOST ALWAYS INCLUDES SOME DISEASE-CAUSING ORGANISMS: PATHOGENS AND PARASITES. EACH ORGANISM IN THE MICROBIOME INTERACTS NOT ONLY WITH THE HOST, BUT WITH OTHER ORGANISMS IN THE MICROBIOME. ALSO, EACH HOST'S MICROBIOME IS DIFFERENT. SOME HOSTS MAY HAVE A MICROBIOME THAT PARTIALLY PROTECTS THEM AGAINST INFECTION BY PATHOGENS TRANSMITTED FROM OTHER HOST INDIVIDUALS. A CURRENT SCIENTIFIC ISSUE IS HOW TRANSMISSION OF PATHOGENS ACROSS THE POPULATION OF HOSTS IS INFLUENCED BY THE DIFFERENCES BETWEEN HOSTS IN THEIR MICROBIOMES. THAT IS THE ISSUE THAT WILL BE ADDRESSED BY THIS PROJECT. THIS PROJECT WILL STUDY THE MICROBIOME OF LEAVES OF THE AGRICULTURALLY IMPORTANT GRASS TALL FESCUE. THE MICROBIOME OF LEAVES IS DOMINATED BY FUNGI, AND ACCORDINGLY THE PROJECT WILL STUDY FUNGAL SPECIES THAT RANGE FROM PATHOGENS TO MUTUALISTS OF THE PLANT. THE PROJECT WILL TEST WHETHER KEY MEMBERS OF THE MICROBIOME CAN REDUCE PATHOGEN INFECTION OF HOST INDIVIDUALS, AND UNDER WHAT CONDITIONS THEY CAN ALSO REDUCE PATHOGEN TRANSMISSION ACROSS THE HOST POPULATION. THIS WILL BE DONE BY INTEGRATING A RANGE OF METHODS, INCLUDING HIGH-THROUGHPUT GENOMIC SEQUENCING, FIELD EXPERIMENTS, GREENHOUSE EXPERIMENTS, FIELD SURVEYS, AND MATHEMATICAL MODELS. THE ULTIMATE GOAL OF THE PROJECT IS TO BETTER UNDERSTAND ROLE OF THE MICROBIOME IN PATHOGEN TRANSMISSION. IN THE LONG-TERM, THIS PROJECT MAY PROVIDE INSIGHTS INTO SUSTAINABLE MANAGEMENT OF PESTS. THE FOCAL PATHOGENS ARE SOME OF THE MOST IMPORTANT PESTS OF PASTURES, TURF GRASS, AND SMALL GRAIN CROPS, AND TALL FESCUE IS ONE OF THE MOST IMPORTANT GRASSES FOR BOTH TURF AND FEEDING LIVESTOCK. MOREOVER, THE PROJECT AIMS TO PROVIDE GENERAL UNDERSTANDING THAT WILL APPLY ACROSS SYSTEMS, POTENTIALLY PROVIDING A BASIS FOR IMPROVEMENTS IN PLANT, ANIMAL, AND HUMAN HEALTH.