Effects of Endophytic Fungi and Arbuscular Mycorrhizal Fungi on Microbial Community Function and Metabolic Pathways in the Rhizosphere Soil of Festuca rubra.

Numerous studies have shown that there are many uncertainties associated with the interactions of nitrogen with plants and microorganisms. In particular, the effects of symbioses between plants and various microorganisms on soil microbial community function remain unclear. Metagenomic sequencing was used to explore the changes in microbial community composition, function and metabolic pathways in rhizosphere soil and the associated influencing factors under different nitrogen levels caused by arbuscular mycorrhizal fungi (AMF) inoculation of F. rubra infected with endophytic fungi and nonendophytic fungi. Plant nutrient allocation (aboveground/belowground), soil pH, and enzymatic activities significantly modulated the functional profiles of the bacterial, fungal, and archaeal communities within these rhizospheres. Soil β-glucosidase activity had the greatest effect on the cluster of orthologous groups of proteins (COG) function of the rhizosphere soil bacterial community, and soil L-leucine aminopeptidase had the greatest effect on the COG function of the rhizosphere soil fungal and archaeal communities. The contributions of AMF colonization to the kyoto encyclopedia of genes and genomes (KEGG) functions of bacteria and archaea in the rhizosphere soil were greater than those of F. rubra infection with endophytic fungi, and AMF colonization improved the metabolic pathways, secondary metabolite biosynthesis, microbial metabolism, amino acid biosynthesis and carbon metabolism of bacterial and archaeal communities in the rhizosphere soil of F. rubra. The effects of endophytic fungi and AMFs on the function and metabolic pathways of symbiotic rhizosphere soil microbial communities were heterogeneous. This study revealed that considering both biotic and abiotic factors is essential for predicting the maintenance of soil ecosystem function by plant-fungal symbionts.