Abstract Cross-kingdom RNA interference is an emerging concept in plant–pathogen interactions. Here we provide evidence that cross-kingdom RNA interference also occurs in a beneficial plant symbiosis called arbuscular mycorrhiza. The arbuscular mycorrhizal fungus Rhizophagus irregularis transfers small RNAs into plant cells, promoting the colonization of host roots. This finding establishes inter-organismal RNA communication as a new regulatory mechanism of this ancient and widespread symbiosis.
Usländer et al. (2026) studied this question.