A Comparative Study On Compositions And Diversities Of Soil Fungal Communities In Rhizosphere Of Common Plants In The Songnen Grassland

The interaction between plants and their rhizosphere soil fungi has an important impact on the structure,function,and stability of the ecosystem.Arbuscular mycorrhizal fungi(AM fungi)are fungal groups that can form a symbiotic relationship with most higher plants and play many key roles in grassland ecosystem functions.However,it is still poorly understood whether there is a specific relationship between grassland plants and their rhizosphere soil fungal communities(including AM fungi)and how their mechanisms are.In this study,common plants in the Songnen grassland were used as research objects.The composition and diversity of soil fungal communities and AM fungal communities in the rhizosphere of each plant were measured,and the effects of physical and chemical properties of rhizosphere soil on the composition and diversity of soil fungi and AM fungi were analyzed.The main conclusions were as follows:(1)Using high-throughput sequencing,10 phyla,23 classes,51 orders,104 families,179 genera,and 153 species of fungi were identified from rhizosphere soils of Carex duriuscula,Calamagrostis rigidula,Leymus chinensis,Lespedeza daurica,Lespedeza hedysaroides,and Vicia amoena.Among them,the relative abundance of Ascomycota,Glomeromycota,Mortierellomycota,Chytridiomycota,and Cercozoa was significantly different(P<0.05)or extremely significant difference(P<0.01)among rhizospheres of different plant species.Each plant had its own fungal OTUs.NMDS analysis showed that there were significant differences in the composition of the fungal OTUs in the rhizosphere soil of each plant.The Ace index(P=0.000),Chao1 index(P=0.000),and Shannon-Wiener index(P=0.044)of soil fungi were significantly different among the rhizosphere of the different plants.(2)Using wet sieving and spore morphology identification,24 species of AM fungi belonging to six genera were identified in the rhizosphere soil of Leymus chinensis,Calamarostis rigidula,Lespedeza hedysaroides,Vicia amoena,Carex duriuscula,and Artemisia lavandulaefolia.The dominant genera were Acaulospora and Glomus.The dominant species were Glomus claroideum and Glomus melanosporum.The subdominant species and companion species of AM fungal communities in the rhizosphere of different plants differed greatly.In general,the species richness(P=0.001),Shannon-Wiener index(P=0.004),spore density(P<0.001),and infection rate(P=0.001)of AM fungi were significantly different among the rhizosphere of the different plants.The similarity coefficients of the AM fungal composition of different plants varied greatly.(3)The Soil water content(SWC),pH,electrical conductivity(EC),available nitrogen(AN),available phosphorus(AP),and microbial biomass carbon(MBC)in the rhizospheresoil of different plants were significantly different(P<0.05),which indicates that the microenvironment of rhizosphere soil of different plants is significantly different.The soil parameters that had a significant impact on the composition of the soil fungal community were SWC,pH,EC,and AN.The soil parameters that had a significant impact on the soil fungal diversity indexes were SWC and AN.The soil parameters that had a significant impact on AM fungal diversity indexes and spore densities were total organic carbon(TOC)and MBC.In summary,several common plants in the Songnen grassland had certain specific selection relationships to their rhizosphere fungal communities and AM fungal communities.Plant species properties determined the composition and diversity of soil fungal communities to a certain extent.This conclusion supported the "Singular hypothesis" in the relationship between plant diversity and soil microbial diversity.We found that changes in the rhizosphere soil microenvironment played a key role in forming the specific relationship between plant species and their rhizosphere fungi.This study provided direct evidence of the specific relationship between grassland plants and their rhizosphere fungal communities.This is of great significance to reveal the role and mechanism of plant-soil interactions in maintaining species diversity and functional stability of grassland ecosystems.