Fungal adaptations to nitrogen shortage – from genes to ecosystems

Explicit inclusion of microorganisms in decomposition models requires data on microbial traits. Such data are scarce, particularly for fungi - the principal drivers of plant litter decomposition.

Here we explore fungal adaptations to nitrogen scarcity in laboratory experiment, models, and by metatranscriptomics in the field.

We will grow genome sequenced fungal strains and natural communities on “artificial litter” with varying nitrogen availability, and monitor changes in growth, respiration, decomposer enzymes and mycelial nitrogen recycling (vacuolization, autophagy, cell wall degradation).

These empirical data will be used to parameterize a mathematical decomposition model, to compare the regulatory importances of different adaptation mechanisms.

Expression of selected gene families will be evaluated for correlation with different adaptations, and transcription of these markers will then be evaluated in soil metatranscriptomes from forest plots with contrasting natural nitrogen availability.

We hypothesise that increased mycelial recycling of nitrogen under nitrogen deficiency will be more important than the more widely recognized adaptations of microbial metabolism and enzyme release.

Quantification of fungal traits and their variation under realistic field conditions is urgently needed, to pave the way for a broader application of microbe-explicit ecosystem models with improved capacity to predict responses of litter decomposition to environmental change.