We use the premier model plant species, Arabidopsis thaliana, and real world plant pathogens like the bacteria Pseudomonas syringae and the oomycete Hyaloperonospora parasitica to understand the molecular nature of the plant immune system, the diversity of pathogen virulence systems, and the evolutionary mechanisms that influence plant-pathogen interactions. All of our study organisms are sequenced, making the tools of genomics accessible.