Spatiotemporal regulation of arbuscular mycorrhizal symbiosis at cellular resolution [MC]

We pioneered AM-inducible TRAP-seq (Translating Ribosome Affinity Purification followed by RNA-seq) using stage-specific promoters, enabling cell-type- and stage-resolved profiling for the first time in AM symbiosis. This revealed extensive spatiotemporal reprogramming of nutrient transport and signaling, with distinct sets of phosphate, nitrogen, and carbon transporters and regulators upregulated or repressed at different stages of arbuscule development, suggesting that nutrient exchange is dynamically regulated across the arbuscule life cycle.

More broadly, cell wall biosynthesis genes and key defence markers were suppressed during arbuscule formation, whereas upon collapse, defence markers were strongly upregulated, suggesting a host-driven shift towards symbiosis termination. Together, these findings highlight the nuanced and dynamic regulation of AM symbiosis at cellular resolution, refining our understanding of how nutrient exchange and fungal development are coordinated in space and time, and providing a framework for further functional exploration.