Grass-endophyte symbiosis: A neglected aboveground interaction with multiple belowground consequences

► Epichloe fungal endophytes can modify the structure and function of belowground ecosystem components. ► Based on a review and meta-analyses, we detected changes in host traits and the processes regulated by them. ► Endophyte reduced host root biomass, mycorrhizal colonization and decomposition, and increased root exudation. ► We were not able to evaluate other key soil processes and components due to the virtual absence of empirical data. ► Grass-endophyte symbiosis is a promising interaction and a critical tool for sustainable agriculture.