This summer, the Princeton iGEM team will be undertaking a synthetic biology project to compete in the iGEM competition this coming fall semester. My proposed project embarks on the global issue of Pseudomonas syringae, a devastating plant pathogen that infects crops worldwide. Current diagnostic methods and treatments for P. syringae have significant limitations - they are time-consuming, lack specificity, or rely on antibiotics and copper products that can lead to antibiotic resistance and accumulation in the environment. The goal is to synthetically engineer Bacillus subtilis, a safe bacteria, as a biosensor to detect the pathogen and suppress its virulence. Our engineered bacteria will tackle three main components: detection, amplification, and secretion. The first section involves B. subtilis to detect the toxin coronatine, secreted by P. syringae, using the COI1-JAZ receptor; this will be done by increasing COI1-JAZ receptor presence on the cell membrane. A small detection signal will control a multi-layered transcriptional amplifier to achieve a hypersensitive response (second step). The transcriptional amplifier will drive the expression of quorum-quenching enzyme AiiA to degrade acyl-homoserine lactone (AHL) quorum-sensing molecules that regulate P. syringae virulence, and a fluorescent protein (GFP) to signify P. syringae presence to farmers (step three). Quorum-quenching is a strategy where phytopathogen signaling is muted to downregulate the virulence factor expression. AiiA will be engineered with a secretion tag and its expression linked to the last amplifier from step two. The complete system will be tested by co-culturing with P. syringae and assessing pathogen growth and virulence factor production.