Effects Of Endophytic Fungi And AMF On Rhizosphere Microbial Community Characteristics Of Festuca Rubra L. Under Different Nitrogen Conditions

Endophytic fungi and arbuscular mycorrhizal fungi(AMF)are two types of fungi,which are widely existing in natural ecosystems.Grass could be infected by both endophytic fungi and arbuscular mycorrhizal fungi at the same time,and formed plant-microbial symbiote.The relationship between plants and microorganisms was affected by a variety of biological and abiotic factors.Nitrogen plays an important role in promoting plant growth and increasing plant biomass as an essential element for plant growth and development.In recent years,a large number of studies focused on the promotion of nitrogen uptake and utilization by endophytic fungi and AMF,but the effects of endophytic fungi and AMF on rhizosphere microbial community under nitrogen regulation were relatively few.Based on this,this study explored the effects of endophytic fungi and AMF infection on ecophysiological characteristics of Festuca rubra L.under different nitrogen conditions through pot experiments.Metagenomic sequencing technology was used to identify the influence and driving factors of the rhizosphere soil microbial community structure and function of F.rubra.The main results were as follows:1.AMF significantly affected the total carbon and underground total sulfur contents of F.rubra under different nitrogen conditions.The double infections of AMF and endophytic fungi had significant effects on the underground total nitrogen content of plants.2.There were significant differences in rhizosphere soil microbial community structure and diversity between endophytic fungi and AMF infected in F.rubra under different nitrogen levels.The main enzyme activity driving factors of dominant bacteria,fungi and archaea communities were soil neutral phosphatase(NP),polyphenol oxidase(PPO)and soil leucine aminopeptidase(L-LAP)in rhizosphere soil of F.rubra,respectively.Actinomycetes were negatively correlated with p H in the rhizosphere soil bacteria community of F.rubra.Gemmatimonadetes,Verrucobacteria,Chlamydiae,Deinococcus and Elusimicrobia were marked positive correlated with soil L-LAP,as well as Euryarchaea,Woesearchaeota and Bathyarchaeota in the archaea community.Basidiomycetes were negatively correlated with soil p H,Mucoromycota and Microsporidia were positively correlated with soil Polyphenol oxidase(PPO)activity.3.Endophytic fungi and AMF infection had significant effects on rhizosphere soil microbial community function under different nitrogen levels.Both endophytic fungi and AMF affected community function by changing rhizosphere microbial community composition.The metabolic pathway function of the rhizosphere soil microbial community in the F.rubra infected by endophytic fungi and AMF was the highest under different nitrogen levels.KEGG function,COG function and CAZy(class level)function of the bacterial,fungal and archaea community in the rhizosphere soil of the F.rubra were significantly correlated with environmental factors.4.Aboveground and underground nutrient content,soil p H and soil enzyme activity of F.rubra were the key ecological factors affecting the function of soil bacteria,fungi and archaea communities.Soil β-GC activity had the greatest influence on COG function of the rhizosphere soil bacterial community,and soil L-LAP was the main influencing factor of COG function of soil fungal and archaea community,as well as KEGG function of soil bacterial community.The community diversity of bacteria,fungi and archaea was significantly correlated with the functional diversity of COG in the rhizosphere soil of F.rubra.Proteobacteria in the rhizosphere soil bacteria community were the major contributors to COG function,KEGG function and CAZy function.The major contributors to KEGG function were Chytridomycetes,Ascomycetes and Euryarchaea.5.Endophytic fungi and AMF had significant effects on microbial community metabolic pathways and nitrogen metabolism in rhizosphere soil of F.rubra under different nitrogen levels.AMF infection improved the metabolic pathways,biosynthesis of secondary metabolites,microbial metabolism,amino acid biosynthesis and carbon metabolism of the bacterial and archaea communities in the rhizosphere soil.Endophytic fungal infection significantly improved the metabolic pathways and biosynthesis of secondary metabolites of the fungal communities in the rhizosphere soil.In conclusion,endophytic fungi and AMF infection could significantly affect the ecophysiological characteristics and rhizosphere soil microbial community structure and composition of F.rubra under different nitrogen conditions.In addition,endophytic fungi and AMF had different functions in regulating rhizosphere microbial community.This study could provide scientific basis for understanding the mechanism of plant-microbial interaction,and provide theoretical support for exploring the mechanism of biological factors affecting the function and metabolic pathway of soil microbial community.