Arbuscular mycorrhizal dialogues: do you speak ‘plantish’ or ‘fungish’?

•Plants rely on their associated microbiota for crucial physiological activities.•We focus on the arbuscular mycorrhizal (AM) symbiosis that involves the Glomeromycota fungi.•We propose that the molecules involved in inter-kingdom symbiotic signaling have key roles originally unrelated to symbiosis.•Thus, the symbiotic role of these molecules relies on the co-evolved capacity of the AM partners to perceive and interpret them as symbiotic signals.

Plants rely on their associated microbiota for crucial physiological activities; realization of this interaction drives research to understand inter-domain communication. This opinion article focuses on the arbuscular mycorrhizal (AM) symbiosis, which involves the Glomeromycota, fungi that can form a symbiosis with most plants. Here we propose the hypothesis that the molecules involved in inter-kingdom symbiotic signaling, such as strigolactones, cutin monomers, and chitin-related molecules, also have key roles in development, originally unrelated to symbiosis. Thus, the symbiotic role of these molecules relies on the co-evolved capacity of the AM partners to perceive and interpret them as symbiotic signals.