Light bolsters plant defenses against pathogens, but the role of light in influencing the virulence and behavior of plant pathogens is poorly understood. Photosensory proteins in plant pathogenic bacteria provide an experimental means to link light cues to specific behavioral outcomes. A project led by Professor Gwyn Beattie in the Department of Plant Pathology and Microbiology is using RNA sequencing (RNA-seq) to identify pathogen genes that respond to light of various wavelengths, and the subsets of these genes that depend on each of the photosensory proteins. Behavioral studies of pathogens altered in light-regulated genes are providing insights into the role of photosensing in pathogen biology.