Mycorrhizal C/N ratio determines plant-derived carbon and nitrogen allocation to symbiosis

Pena, R. ORCID: https://orcid.org/0000-0002-7985-6906, Bluhm, S. L., Ammerschubert, S., Agüi-Gonzalez, P. ORCID: https://orcid.org/0000-0002-2313-1439, Rizzoli, S. O. ORCID: https://orcid.org/0000-0002-1667-7839, Scheu, S. and Polle, A. ORCID: https://orcid.org/0000-0001-8697-6394 (2023) Mycorrhizal C/N ratio determines plant-derived carbon and nitrogen allocation to symbiosis. Communications Biology, 6. 1230. ISSN 2399-3642 doi: 10.1038/s42003-023-05591-7

Abstract/Summary

Carbon allocation of trees to ectomycorrhizas is thought to shape forest nutrient cycling, but the sink activities of different fungal taxa for host resources are unknown. Here, we investigate fungal taxon-specific differences in naturally composed ectomycorrhizal (EM) communities for plant-derived carbon and nitrogen. After aboveground dual labeling of young beech with 15N and 13C, ectomycorrhizas formed with different fungal taxa exhibit strong differences in label enrichment. Secondary Ion Mass Spectrometry (SIMS) imaging of nitrogen in cross sections of ectomycorrhizas demonstrates plant-derived 15N in both root and fungal structures. Isotope enrichment in ectomycorrhizas correlates with that in the corresponding ectomycorrhiza-attached lateral root, supporting fungal taxon-specific N and C fluxes in ectomycorrhizas. The enrichments with 13C and 15N in the symbiosis decrease with increasing C/N ratio of ectomycorrhizas, converging to zero at high C/N. The relative abundances of EM fungal species on roots are positively correlated with 13C enrichment, demonstrating higher fitness of stronger than of less C-demanding symbioses. Overall, our results support that differences among the C/N ratios in ectomycorrhizas formed with different fungal species regulate the supply of the symbioses with host-derived carbon and provide insights on functional traits of ectomycorrhizas, which are important for major ecosystem processes.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/114373
Identification Number/DOI	10.1038/s42003-023-05591-7
Refereed	Yes
Divisions	Life Sciences > School of Agriculture, Policy and Development > Department of Sustainable Land Management > Centre for Agri-environmental Research (CAER)
Uncontrolled Keywords	Mycorrhizae, Plants, Carbon, Nitrogen, Ecosystem, Symbiosis
Publisher	Nature Research
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