Perception of a pathogenic signature initiates intergenerational protection

Transmission of immune responses from one generation to the next represents a powerful adaptive mechanism to protect an organism's descendants. Parental infection by the natural C. elegans pathogen Pseudomonas vranovensis induces a protective response in progeny, but the bacterial cues and intergenerational signal driving this response were previously unknown. Here we find that animals activate protective stress response pathways in response to bacterial cyanide, and that a metabolic byproduct of cyanide detoxification, beta-cyanoalanine, acts as an intergenerational signal to protect progeny from pathogen exposure. Remarkably, this mechanism does not require direct parental infection; rather; exposure to pathogen-derived volatiles is sufficient to enhance survival of the next generation, indicating that parental surveillance of environmental cues can activate a protective intergenerational response. Therefore, the mere perception of a pathogen-derived toxin, in this case cyanide, can protect an animal's progeny from future pathogenic challenges.