Rethinking AMF-mediated nutrient cycling through microbial necromass

Arbuscular mycorrhizal fungi (AMF) are commonly described as nutrient pipelines that transfer mineral nutrients to plants in exchange for photosynthetically derived carbon. Although this framework has been highly productive, it underrepresents the role of extraradical AMF hyphae as microbial interfaces within soil. AMF hyphae release carbon-rich compounds, shape hyphosphere microbiomes, and interact with microorganisms capable of mobilizing organic nutrient pools that AMF alone may access inefficiently. Here, we propose the necromass-broker hypothesis , whereby AMF hyphae generate carbon-subsidized microbial hotspots in which microbial growth, nutrient immobilization and turnover produce necromass-derived mineral nutrient pools that can be mobilized by hyphosphere decomposers and partly recaptured through the mycorrhizal pathway. This Perspective does not suggest that AMF are classical saprotrophs, nor that direct nutrient transfer is secondary. Rather, it proposes that AMF-mediated nutrient cycling may include an overlooked microbial-turnover component linking plant carbon allocation, hyphosphere community assembly, microbial necromass decomposition and nutrient recovery. Under this framework, AMF may alleviate plant–microbe nutrient competition not by preventing microbial immobilization, but by spatially coupling microbial turnover with delayed nutrient recycling. Recognizing AMF as potential microbial recycling interfaces provides a new perspective on nutrient cycling in the hyphosphere and may help improve soil fertility management, organic amendment strategies and microbiome-based agriculture.