Dr. Darrell Desveaux’s research is based on determining the molecular mechanisms of bacterial virulence and plant disease resistance. Many gram negative bacterial pathogens use the type III secretion system to inject proteins directly into host cells. These type III effectors, or virulence proteins, often target specific host proteins to modify the cellular environment to favour the infection process. This can lead to an observable increase in the virulence of pathogens expressing specific type III effectors. Plants have evolved resistance (R) proteins to detect the modifications induced by effectors and subsequently mount effective defence responses to avoid the infection process. Consequently, certain bacterial effectors have evolved to mask the presence of others, making the pathogen undetectable by the plants surveillance system. Therefore, by injecting a suite of proteins into the host cell, bacteria induce a complex series of molecular modifications which determine the outcome of a plant-pathogen interaction: disease or resistance. Understanding the molecular events induced by type III effectors during a host-pathogen interaction requires the establishment of a network map of effector interactions and characterization of how the targets are modified. The similarities between plant and animal innate immune systems and the common virulence mechanisms used by bacterial pathogens of plants and animals make the experimentally advantageous plant-pathogen system an ideal model to study bacterial pathogenesis of eukaryotic organisms. The Desveaux research group is using proteomics, structural biology, chemical biology, genetics and biochemistry to elucidate the molecular mechanisms of pathogen virulence and host resistance. The research team is also screening libraries of small molecules for compounds that alter the susceptibility of Arabidopsis seedlings to infection by a virulent strain of P. syringae. Using chemical biology the team can utilize small molecules rather than genetic mutations to generate phenotypes of interest.