Role of Rare Taxa in the Structure and Function of Soil Fungal Community

Rare taxa are the potential force influencing function and structure of fungal communities and play an over-proportional role in soil ecosystems. We studied the typical Chernozem soil in Heilongjiang Province using high-throughput analysis techniques to investigate the role of rare taxa in function and structure of fungal communities in Chernozem. Coexistence of various low-abundance rare fungal taxa and few high-abundance fungal taxa were observed in Chernozem. Most of the rich and rare fungal taxa belonged to the phyla Ascomycota and Basidiomycota. No rare fungus from the phylum Mortierellomycota was detected. The primary environmental factor affecting the structure of rare fungal taxa was found to be soil pH, followed by water content. The rich fungal taxon Mortierella had a significantly positive correlation with total phosphorus and organic carbon (P < 0.05). The function prediction revealed 72 significantly different MetaCyc pathways in the two plots, and the rare taxa accounted for 80.56% of the total microbial community. The sulfate reduction pathway I was significantly different at P < 0.001, the octane oxidation pathway and the adenine and adenosine pathway were significantly different at 0.001 ≤ P < 0.01, and the remaining pathways were significantly different at 0.01 ≤ P < 0.05. In summary, the rare fungal taxa are of great significance to maintaining functional diversity and microbial structure of soil.