Endophyte infection influences arbuscular mycorrhizal fungi communities in rhizosphere soils of host as opposed to non-host grass

Endophytes live asymptomatically within many cool-season grasses for at least a portion of their life cycle. Although the leaf endophyte effects on the growth and stress resistance of host grasses have been relatively well studied, less attention has been focused on how this relationship may impact soil microbial communities, especially arbuscular mycorrhizal fungi (AMF). We defined endophyte-infected and endophyte-freeLeymus chinensisas the host grass and neighbouringStipa krylovii, which was not infected by endophytes, as the non-host grass. Our objective was to examine the effect of endophyte infection on the colonization rate and composition of AMF communities in both the rhizosphere and bulk soils of their host (L. chinensis) and a neighbouring non-host (S. krylovii) by a consecutive 2-year survey. We described AMF communities using high-throughput DNA sequencing, quantified the proportion of root length colonized by AMF using microscopy, and estimated AMF biomass using a lipid biomarker. Structural equation modelling (SEM) was applied to disentangle the direct and indirect effects (mediated by multiple environmental factors) of an endophyte on AMF. We found that endophyte infection significantly increased colonization rates and rhizosphere soil biomass of AMF but had no significant effect on the bulk soil around the host grass. The endophyte increased the diversity of the rhizosphere soil AMF community by decreasing the abundance of the dominant speciesGlomuswhile increasing the abundance of some unidentified AMF. SEM showed that the endophyte effects on AMF biomass in rhizosphere soil were primarily mediated by soil total carbon, total nitrogen and pH. With respect to the non-host grass, the endophyte infection of host grass did not change the colonization rates or AMF biomass in either the rhizosphere or bulk soil but did cause a shift in the rhizosphere soil AMF community composition, resulting in a decrease in the relative abundance ofSeptoglomusand an increase in the relative abundance of some unidentified AMF. Highlights center dot Effects of endophyte infection on AMF communities in both the rhizosphere and bulk soils were studied. center dot Endophyte effect was studied not only on the host but also on the non-host grass. center dot Endophyte infection significantly increased colonization rates and rhizosphere soil biomass of AMF. center dot Endophyte effect on AMF biomass in rhizosphere soil was primarily mediated by soil physicochemical properties.