Carbon Allocation Shifts During Fungal Mycelial Competition Under the Heat Stress

Abstract

Wood-decaying basidiomycetes play crucial roles in global carbon cycling. The relative dominance of brown rot and white rot fungi, which vary with temperature, is key to understanding carbon sequestration in a changing environment. In this study, we measured changes in carbon allocation between brown and white rot fungi under heat stress to assess the outcome of their competition. After 25 days of incubation in liquid media, heat stress reduced hyphal biomass and increased CO2 emissions in both Neolentinus (brown rot) and Trichaptum (white rot) strains. However, carbon allocation to metabolite production and unknown fractions shifted markedly in Trichaptum strains under heat stress, whereas changes in Neolentinus strains were less pronounced. Competition between Neolentinus and Trichaptum shifted from a deadlock at optimal temperature to Neolentinus’s dominance under heat stress. These findings suggest that Neolentinus is more heat-tolerant compared to Trichaptum, maintaining more stable metabolic activity under heat stress.

Keywords: brown rot fungi, carbon allocation, CO2 efflux, fungal competition, heat stress, organic acids, polyphenols, white rot fungi