Climate change is predicted to increase the incidence of plant disease, potentially threatening the global food supply. As microbes have greater capacity than plant hosts to adapt quickly to changing climates, microbial community fluctuations and functional shifts may have a strong negative effect on the resistance and resilience of agronomic and natural ecosystems. Therefore, increased knowledge of microbial responses to climate change has high potential to inform management strategies focused on maintaining plant health. A better understanding of the complex interactions between the environment and plant-associated microbiota could transform current approaches to disease control. We aim to use experimental metatranscriptomics to characterize the functional activities of plant-associated microbial communities and host immune responses under climate warming. We focus on pathogens of grasses because grasslands cover 20% of the terrestrial surface of the earth, are critical to the human and animal food supply, and are particularly sensitive to climate change. This project represents a novel direction for the PI’s research program, which has focused on the ecology of host-symbiont interactions and only recently has begun to use next-generation amplicon sequencing to characterize microbial composition. The proposed work would develop a new focus on the mechanisms of host-symbiont interactions, opening up funding opportunities at NSF-IOS and USDA that are currently inaccessible to us. To our knowledge, this would be the first study to use metatranscriptomics to examine the functional gene responses of pathogens and host plants exposed to long-term climate manipulations.