Using Arabidopsis thaliana as a model system, my laboratory studies the mechanisms of plant defense against microbial pathogens. We focus on a specific response known as systemic acquired resistance (SAR). SAR, which can be induced by a local infection, provides the plants with long lasting, systemic resistance against a broad spectrum of pathogens. Salicylic acid (SA; an active ingredient of aspirin) has been found to be the endogenous signal of SAR. Using a genetic approach, our laboratory identified genes involved in the regulation of SAR. Molecular and genetic analyses are being carried out to understand the gene function and to elucidate the SAR signaling pathway. These SAR-regulating genes are also favorite targets for molecular engineering of disease-resistance crops.