The piRNA pathway responds to environmental signals to establish intergenerational adaptation to stress.

Background: piRNAs have a constitutive role in genome defence by silencing transposable elements in the germline. In the nematode Caenorhabditis elegans, piRNAs also induce epigenetic silencing of transgenes, which can be maintained for many generations in the absence of the piRNA pathway. The role of multi-generational epigenetic inheritance in adaptation to the environment is unknown.