Fungal functional gene composition
A total of 2,590 probes of 82 fungal functional genes responsible for nutrient cycling, stress, energy processes, and virulence were detected. In line with our first hypothesis, we found that warming altered the overall functional gene composition significantly (Table 1, P< 0.05), which was further verified by the PCoA plot (Fig. S2b). Therefore, we performed the SIMPER analysis to identify major functional genes responsible for the differences. A total of 12 functional genes had significant contributions (Table 2, P< 0.05), which were associated with C degradation (i.e., genes encoding cellobiase, xylanase, glyoxal oxidase, metalloprotease, phospholipase A2, vanillin dehydrogenase, xylose reductase, invertase), S cycling (i.e., genes encoding sulfate transporter and PAPS reductase), P utilization (i.e., the gene encoding phytase) and stress tolerance (i.e., the gene encoding superoxide dismutase).
In line with our second hypothesis, 3 out of a total of 53 fungal C degradation genes showed significantly (P < 0.05) higher relative abundances under warming , which encode invertase for sucrose degradation (increased by 16.7%), xylose reductase for hemicellulose degradation (increased by 231.62%), and vanillin dehydrogenase for lignin-derived aromatics degradation (increased by 47.64%) (Fig. 1). The gene encoding phytase for P utilization was also significantly increased by 11.37% (P < 0.05). Additionally, a total of 30 oligonucleotide probes of C degradation genes were only detected in warmed samples (Table S2).