Flow chart of the experiments. The study comprised several experiments: two pot experiments, in vitro experiments, and an inoculation experiment. The two pot experiments (pot expts 1 and 2) tested whether the proliferation of AMF into microsites of residues may reduce N 2 O emissions and disassemble the regulation pathway. We also tested the abundance of the microbiome in the hyphosphere; the in vitro experiment assessed the importance of P. fluorescens co-colonization with AMF for reduced N 2 O emissions. We isolated denitrifiers and identified the key components of hyphal exudates. We then examined the chemotaxis, growth, N 2 O emission, and denitrifying gene expression of P. fluorescens in response to AMF exudates and key compounds under in vitro culture conditions; finally, the inoculation experiment validated the effects of AMF or citrate exuded by AMF on N 2 O emissions and nosZ gene expression of P. fluorescens in pot culture. A conceptual model is used to illustrate the pathways by which AMF interact with P. fluorescens to mitigate N 2 O production
