A model-system approach to disentangle the role of intraspecific fungal effects on soil carbon cycling

Fungal mycelia constitute a major structural component of soils and play a central role in carbon (C) cycling. Yet, despite their importance, we lack a mechanistic understanding of how variation in mycelial morphology translates into differences in soil C dynamics and stabilization. In particular, the role of intraspecific variation (i.e. the genetic and phenotypic diversity within a single fungal species) remains largely unexplored. This gap represents a critical barrier to predicting the formation and persistence of soil C pools under ongoing environmental change.

This project addresses this challenge by using the model filamentous fungus Neurospora crassa to test how intraspecific variation influences soil C partitioning and respiration. We quantify how morphologically distinct strains of N. crassa differ in their contributions to soil respiration and to the formation of particulate organic matter (POM) versus mineral-associated organic matter (MAOM). Controlled soil microcosm experiments will allow us to directly link fungal traits (e.g. hyphal density, branching architecture) to C fluxes and stabilization pathways.

By leveraging a model organism, this work enables a level of experimental resolution that is difficult to achieve in complex natural communities. This approach allows us to move beyond species-level averages and explicitly test how individual-level variation shapes ecosystem processes in soils. Ultimately, we aim to identify the fungal traits and underlying genetic mechanisms that promote long-term C stabilization in soils.

By uncovering the mechanistic links between fungal intraspecific diversity and soil C dynamics, this project advances a shift from descriptive to predictive soil ecology. The results will provide a foundation for incorporating fungal trait variation into soil C models, thereby improving predictions of soil C permanence and refining our understanding of fungi as precise, trait-driven regulators of the terrestrial carbon cycle.