The research performed in this laboratory brings together microbiology, immunology, and metagenomics to further understand microbial communities associated with plants. Microbes found in roots perform a variety of functions for their host, including: nutrient acquisition, growth promotion, and disease prevention. We will determine how the immune system in the model plant, Arabidopsis thaliana acts to exclude microbes from joining communities found in root systems. Although a wide diversity of microbes are present in the soil, only limited microbial taxa can colonize inside of the root tissue, indicating that microbes found in the root tissue must pass through several levels of selection. Together, these studies will partially dissect the complex relationship that exists between hosts and their microbial communities and extend our understanding of host immune systems.