PR001813 (Project)

Description:In plants and animals, detection of pathogen-associated molecular patterns (PAMPs) by membrane-localized receptors initiates pattern-triggered (PTI) immunity against pathogens. In plants, many PAMP-induced signaling pathways and cellular responses are known, yet how PTI limits pathogen growth is poorly understood. Through a combined metabolomics and genetics approach, we discovered that plant-exuded proline is a virulence-inducing signal and nutrient for the bacterial pathogen Pseudomonas syringae, and that PAMP-induced depletion of proline from the extracellular spaces of Arabidopsis leaves directly contributes to PTI against P. syringae. We further show that PAMP-induced depletion of extracellular proline requires the amino acid transporter Lysine Histidine Transporter 1 (LHT1). This study demonstrates that depletion of a single extracellular metabolite is an effective component of plant immunity. Given the important role for amino acids as N and C sources for microbial growth, their depletion at sites of infection may be a broadly effective defense against many pathogens.