From genes to epigenomes: rethinking arbuscular mycorrhizal fungi adaptation

Arbuscular mycorrhizal fungi (AMF) form ecologically important mutualisms with most plant species, yet their unpredictable phenotypes and mutualistic outcomes represent a fundamental barrier to our understanding of their ecological functions. While early models focused on genetic differences between species and strains, evidence is mounting that AMF deploy conserved eukaryotic processes to control gene expression through structural DNA modifications, without changes to underlying sequences, or epigenomic processes, to facilitate rapid plasticity and adaptation. In this opinion article, we summarize recent evidence of epigenomic regulation in AMF and how these mechanisms govern interactions with plants. Drawing from well-studied model systems, we outline multigenerational experiments to pinpoint the epigenomic basis of AMF trait variation.