Polyphony in the rhizosphere: presymbiotic communication in arbuscular mycorrhizal symbiosis

The Arbuscular Mycorrhizal (AM) symbiosis is a ubiquitous relationship established in terrestrial ecosystems between the roots of most plants and fungi of the Glomeromycota. AM fungi occur amongst many other inhabitants of the soil, and successful development of AM symbioses relies on a pre-symbiotic signal exchange that allows mutual recognition and reprogramming for the anticipated physical interaction. The nature of some of the signals has been discovered in recent years, providing a first insight into the type of chemical language spoken between the two symbiotic partners. Importantly, these discoveries suggest that the dialogue is complex and that additional factors and corresponding receptors remain to be unveiled. Here, we explore the latest advances in this pre-symbiotic plant-fungal signal exchange and present the resulting current understanding of rhizosphere communication in AM symbioses.