Arbuscular mycorrhiza convey significant plant carbon to a diverse hyphosphere microbial food web and mineral-associated organic matter

Kakouridis, A.; Yuan, M.; Nuccio, E. E.; Hagen, J. A.; Fossum, C. A.; Moore, M. L.; Estera-Molina, K.; Nico, P. S.; Weber, P. K.; Pett-Ridge, J.; Firestone, M. K.

doi:10.1101/2023.07.11.548626

bioRxiv · 10.1101/2023.07.11.548626

Arbuscular mycorrhiza convey significant plant carbon to a diverse hyphosphere microbial food web and mineral-associated organic matter

Kakouridis, A.·Yuan, M.·Nuccio, E. E.·Hagen, J. A.·Fossum, C. A.·Moore, M. L.·Estera-Molina, K.·Nico, P. S.·Weber, P. K.·Pett-Ridge, J.·Firestone, M. K.

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Abstract

O_LIArbuscular mycorrhizal fungi (AMF) transport substantial plant carbon (C) that serves as a substrate for other soil organisms, a precursor of soil organic matter (SOM), and a driver of soil microbial dynamics. Using two-chamber microcosms where an air gap isolated AMF from roots, we 13CO2-labeled Avena barbata for six weeks and measured. the C Rhizophagus intraradices transferred to SOM and hyphosphere microorganisms. C_LIO_LINanoSIMS imaging, IRMS, 13C NMR, and SOM density fractionation showed hyphae and roots had similar 13C enrichment. AMF transferred 0.77 mg C per g of soil (increasing total C by 2%); 33% was found in occluded or mineral-associated pools, primarily as carbohydrates. C_LIO_LIIn the AMF hyphosphere, there was no overall change in community diversity but 36 bacterial ASVs significantly changed in relative abundance. With stable isotope probing (SIP)-enabled shotgun sequencing, we found taxa from the Solibacterales, Sphingobacteriales, Myxococcales and Nitrososphaerales (ammonium oxidizing archaea) were highly enriched in AMF-imported 13C (>20 atom%). Mapping 13C-enriched metagenome-assembled genomes to total ASVs showed at least 92 bacteria and archaea were significantly 13C-enriched. C_LIO_LIOur results illustrate the quantitative impact of hyphal C transport on the formation of potentially protective SOM pools and indicate microbial roles in the AMF hyphosphere soil food web. C_LI

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Kakouridis, A., Yuan, M., Nuccio, E. E., Hagen, J. A., Fossum, C. A., Moore, M. L., Estera-Molina, K., Nico, P. S., Weber, P. K., Pett-Ridge, J., Firestone, M. K.. 2023-07-11. Arbuscular mycorrhiza convey significant plant carbon to a diverse hyphosphere microbial food web and mineral-associated organic matter. https://doi.org/10.1101/2023.07.11.548626

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