A Study Of Arbuscular Mycorrhizal Fungal Diversity And Community Composition Along Temperate Gradient In Grassland Ecosystem

Arbuscular mycorrhizal (AM) fungal are widely considered as important linkages between aboveground vegetation and belowground soil in terrestrial ecosystems. The changes in mycorrhizal fungal community structures can not only affect the composition of plant communities, but also influence soil properties and nutrient cycling, and therefore play important roles in ecosystem stability and productivity. Understanding the variation of mycorrhizal fungal diversity in the Eurasian temperate grasslands have far-reaching scientific and practical significance, especially because temperate grasslands are among the most sensitive and vulnerable ecosystems under global climate change.In this study, we selected three field sites in Inner Mongolia along the East Eurasian Steppe Transect which goes south to north representing an increasing temperature gradient in typical grasslands, and targeted three dominant plant species (Stipa grandis, Cleistogenes squarrosa and Leymus chinensis) in all three sites. A total of 45 root samples (nine plants X three species X three sites) were collected. A subset of Leymus chinensis roots were stained with trypan blue and scored for AM colonization using the magnified gridline intersect method. The remaining roots were used for molecular analysis on the composition of AM fungal. After DNA extraction, PCR (nested AML1-AML2 within NS1-NS4), cloning and sequencing, we determined the operational taxonomic units (OTUs) of all AM fungal dequences at the level of 97% similarity through a standard OTU analysis. Each OTU was then identified to genus level based on the phylogenetic tree we established with representatice sequences. In total,24 OTUs were identified from our samples, belonging to 3 orders,4 families, and 5 genera (Glomus, Paraglomus, Rhizophagus, Redeckera and Claroideoglomus). Two-factor analysis of variance revelaed that sites, host plant species, and the interactions of site and plant species did not affect the richness of AM fungal,Shannon Wiener index or Simpson index. Nonmetric multidimensional scaling ordination (NMDS) results showed site had significantly influence on the AM fungal community composition, but host plant species had not significant effect on AM fungal diversity and community composition. We found that AM fungal colonization in L.chinensis roots did not vary among sites.