Increases Root Fungal Endophyte Richness and Alters Root Fungal Endophyte Composition in a Changing World.

Plants harbor a variety of fungal symbionts both above- and belowground, yet little is known about how these fungi interact within hosts, especially in a world where resource availability is changing due to human activities. Systemic vertically transmitted endophytes such as spp. may have particularly strong effects on the diversity and composition of later-colonizing symbionts such as root fungal endophytes, especially in primary successional systems. We made use of a long-term field experiment in Great Lakes sand dunes to test whether colonization of the dune-building grass, , could alter fungal root endophyte species richness or community composition in host plants. We also tested whether nitrogen addition intensified the effects of on the root endophyte community. We found that increased richness of root endophytes in by 17% overall, but only shifted community composition of root endophytes under nitrogen-enriched conditions. These results indicate that acts as a key species within , changing richness and composition of the root mycobiome and integrating above- and belowground mycobiome interactions. Further, effects of on root endophyte communities were enhanced by N addition, indicating that this fungal species may become even more important in future environments.