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Low Temperature Enhances N-Metabolism in Paxillus involutus Mycelia In Vitro: Evidence From an Untargeted Metabolomic Study

Summary

This study examined how a common forest fungus (Paxillus involutus) responds to cold temperatures by analyzing its chemical composition. When kept at cold temperatures like those found in spring and autumn forests, the fungus took up and used more nitrogen for making amino acids and other nitrogen compounds, even though it grew more slowly. This suggests that cold-adapted fungi have special mechanisms to acquire nutrients efficiently in cold conditions, which may be important for how they help trees survive in changing climates.

Background

Ectomycorrhizal fungi (ECMF) are major plant symbionts that influence nutrient uptake and stress resistance. While most molecular studies on ECMF have been conducted at laboratory temperatures around 21°C, ECMFs naturally occur in cold northern hemisphere habitats and are frequently exposed to low temperatures. Despite their prevalence in cold environments, molecular research on ECMF response to low temperature is sparse.

Objective

This study investigated the molecular response of Paxillus involutus mycelia to prolonged low temperature (4°C) exposure using untargeted GC-MS/MS metabolomic analysis. The goal was to understand how nitrogen and carbon metabolism shift under low temperature conditions and what this reveals about fungal cold adaptation mechanisms.

Results

Low temperature exposure caused drastic growth reduction and mild oxidative stress. Despite reduced growth, nitrogen concentration significantly increased and nitrogen metabolism via the GS-GOGAT pathway was enhanced with elevated amino acid levels. Carbon metabolism was not suppressed but redirected toward stress-related metabolites like trehalose and inositol, with increased carbohydrate intermediates for nitrogen compound biosynthesis.

Conclusion

Low temperature enhanced nitrogen metabolism in P. involutus mycelia even without additional carbon supply, suggesting decoupling of C and N acquisition. These findings indicate that low temperatures may trigger early cold-adaptation mechanisms in ECM fungi, with potential implications for symbiotic balance and fungal function under climate change scenarios in northern forests.
  • Published in:Environmental Microbiology,
  • Study Type:Experimental Study,
  • Source: PMID: 40796359
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