C. elegans aversive olfactory learning generates diverse intergenerational effects

Parental experience can modulate the behavior of their progeny through the inheritance of phenotypic traits acquired by the progenitors. While the molecular mechanisms for behavioral inheritance have been studied under several environmental conditions, it remains largely unexplored how the nature of the parental experience affects the information transferred to the next generation. To address this question, we used C. elegans, a nematode that feeds on bacteria in its habitat. Some of these bacteria are pathogenic and the worm learns to avoid them after a brief exposure. We found, unexpectedly, that a short parental experience increased the preference for the pathogen in the progeny. Furthermore, increasing the time of parental exposure switched the response of the progeny from attraction to avoidance. To characterize the underlying molecular mechanisms, we found that the RNA-dependent RNA Polymerase (RdRP) RRF-3, required for the biogenesis of 26G endo-siRNAs, regulated both types of intergenerational effects. Together, we show that different parental experiences with the same environmental stimulus generate diverse effects on the behavior of the progeny through small RNA-mediated regulation of gene expression.