Arbuscular mycorrhizal fungi (AMF) hold tremendous potential towards a more sustainable agriculture. Nevertheless, agricultural application is hindered by unpredictable symbiotic outcomes. Overcoming this bottleneck necessitates an enhanced understanding of the plant immune response and fungal effectors active during symbiosis. Single-cell-omics enables us to elucidate this molecular arms-race with a high spatiotemporal resolution via snRNA-seq and proteomic profiling of arbusculated cells.