THIS PROJECT AIMS TO INVESTIGATE THE DYNAMIC INTERACTIONS WITHIN THE BARLEY MICROBIOME DURING FUSARIUM HEAD BLIGHT (FHB) INFECTION. OUR EXTENSIVE SURVEY OF MICROBIOME COMPOSITION ACROSS FOUR LOCATIONS IN THE US DURING FHB INFECTION OF BARLEY REVEALED THE MICROBIOME UNDERGOES SIGNIFICANT ALTERATIONS IN RESPONSE TO DISEASE PRESENCE, AND THE RESPONSE WAS MORE PRONOUNCED IN THE FUNGAL COMMUNITY. THIS OBSERVATIONAL DATA AND CULTURE COLLECTIONS OF THE CORE MICROBIOME HAS DRIVEN US TO INVESTIGATE THE PHYLLOSPHERE SUPPRESSIVE FUNCTIONS OF THE BARLEY MICROBIOME AND ASSEMBLAGE OF TRANSKINGDOM COMMUNITIES IN THE CONTEXT OF ENEMY RECOGNITION AND HOST IMMUNE RESPONSE. HERE WE EXPLORE THESE CONCEPTS WITH THREE PRIMARY OBJECTIVES. FIRSTLY, WE SEEK TO ESTABLISH THE BARLEY PHYLLOSPHERE AS A MODEL SYSTEM FOR STUDYING TRANSKINGDOM MICROBIOME ASSEMBLY MECHANISMS USING SYNTHETIC COMMUNITIES. SECONDLY, WE AIM TO DETERMINE WHETHER MICROBES RECRUITED DURING DISEASE OR FROM A NON-DISEASED/HEALTHY STATE ARE MORE EFFECTIVE IN MITIGATING THE DISEASE'S IMPACT. THIS INVOLVES PERFORMING DROP-OUT EXPERIMENTS WITH SYNTHETIC COMMUNITIES FOR THEIR EFFECTS ON PLANT HEALTH AND FUSARIUM INHIBITION. FINALLY, WE PLAN TO INVESTIGATE THE MECHANISMS UNDERLYING ASSEMBLY OF PHYLLOSPHERE MICROBES, USING EXTERNAL MAMPS APPLICATION AND FUSARIUM MUTANTS TO ASSESS THE ROLE OF MICROBIAL RECOGNITION AND PLANT IMMUNITY AS BIOTIC SELECTORS. THIS COMPREHENSIVE APPROACH WILL DEEPEN OUR UNDERSTANDING OF THE INTRICATE RELATIONSHIPS BETWEEN BARLEY, ITS MICROBIOME, AND FUSARIUM INFECTION, POTENTIALLY OPENING NEW AVENUES FOR DISEASE MANAGEMENT STRATEGIES.