Ecologists have frequently observed a pattern of fungal succession during litter decomposition, wherein different fungal taxa dominate different stages of decay. However, the biological mechanisms driving fungal ecological succession remain unknown. We hypothesized that genome composition determines fungal community assembly due to presence/absence and copy number variation (CNV) of protein-coding families involved in plant biopolymer breakdown and hyphal growth. To test this hypothesis, we explored the fully sequenced genomes of species from 49 fungal decomposer genera that preferred early, middle, or late stages of plant litter decay. Using R’s multipatt function, we calculated the Pearson rho correlation of 5,657 protein domain annotation counts with decay stage preference and identified 8 Pfam domains associated with early stage, 12 Pfam domains associated with middle stage, and 17 Pfam domains associated with late stage. We used dcGO to identify the biological processes most strongly linked to these domains.
Results/Conclusions
Protein domains significantly associated with early colonization were involved in microtubule formation (p<0.05), mitochondrial respiration (p<0.05), and membrane transport (p<0.05), suggesting that early-colonizing species are those with rapid growth ability. Domains significantly associated with mid-decay colonization were involved in pectin breakdown (p=0.05), starch breakdown (p=0.05), and cellulose binding (p=0.05). The domains significantly associated with late colonization were involved in oxidative substrate breakdown (p<0.05), mRNA silencing (p<0.05), and vesicular transport (p<0.05). These results suggest that differences in fungal decomposers’ growth rates, and in their fundamental abilities to break down various plant biopolymers, may help drive fungal community assembly and turnover during plant litter decay.