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Research Project: Discovery of Plant Genetic Mechanisms Controlling Microbial Recruitment to the Root Microbiome

Location: Plant Gene Expression Center

Title: Keep your friends close: Host compartmentalisation of microbial communities facilitates decoupling from effects of habitat fragmentation

item WILLING, CLAIRE - University Of California
item PIERROZ, GRADY - University Of California
item GUZMAN, AIDEE - University Of California
item ANDEREGG, LEANDER - University Of California
item GAO, CHENG - University Of California
item Coleman-Derr, Devin
item TAYLOR, JOHN - University Of California
item BRUNS, TOM - University Of California
item DAWSON, TODD - University Of California

Submitted to: Ecology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2021
Publication Date: 9/14/2021
Citation: Willing, C., Pierroz, G., Guzman, A., Anderegg, L., Gao, C., Coleman-Derr, D.A., Taylor, J., Bruns, T., Dawson, T. 2021. Keep your friends close: Host compartmentalisation of microbial communities facilitates decoupling from effects of habitat fragmentation. Ecology Letters. 24(12):2674–2686.

Interpretive Summary: Root-associated fungal communities modify the climatic niches and even competitive ability of their hosts, yet how the different components of the root microbiome are modified by habitat loss remains a key knowledge gap. Using principles of island biogeography, we tested how free- living versus host-associated microbes might differ in their response to landscape heterogeneity. Further, we explore how compartmentalization of microbes into specialized root structures might filter for key fungal symbionts. Our study demonstrates that free-living fungal community structure correlates with landscape heterogeneity, but that host-associated fungal communities depart from the principles of island biogeography. Specifically, biotic filtering in roots, especially via compartmentalization within specialized root structures, decouples the biogeographic patterns of host-associated fungal communities from the soil community. In this way, even as habitat loss and fragmentation threaten fungal diversity in the rhizosphere, plant hosts exert biotic controls to ensure associations with critical mutualists, helping to preserve the root mycobiome.

Technical Abstract: The present study tests how changes in the coast redwood habitat structures fungal community composition in these forests. In addition, we report for the first time that swollen, nodule-like structures (herein “rhizonodes”) are present on redwood roots, raising questions about their role in compartmentalization of fungal mutualists in the face of habitat loss and fragmentation. Specifically, we address three hypotheses: (H1) that the extent of redwood habitat cover and fragmentation will drive community structure and richness of soil fungal communities; (H2) that fungal community structure associated with redwood roots will be decoupled from biogeographic patterns found for soil fungi as a result of strong biotic filtering; and (H3) that compartmentalization will further facilitate the biotic filtering of the fungal community by enriching for symbiotrophic taxa in specialized root structures (rhizonodes). Additionally, we test if rhizonodes explicitly compartmentalize AMF, akin to a mycorrhizal version of a N-fixing nodule.