Preferential assimilation, metabolism, and transfer of organic nitrogen to host plants by Mucoromycotina 'fine root endophytes'

Howard, N. O. A.; Williams, A.; Durant, E.; Pressel, S.; Daniell, T. J.; Field, K. J.

doi:10.1101/2024.07.31.606011

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bioRxiv · 10.1101/2024.07.31.606011

Preferential assimilation, metabolism, and transfer of organic nitrogen to host plants by Mucoromycotina 'fine root endophytes'

Howard, N. O. A.·Williams, A.·Durant, E.·Pressel, S.·Daniell, T. J.·Field, K. J.

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Abstract

O_LIMucoromycotina fine root endophytes (MFRE) are an understudied group of plant fungal symbionts that usually co-occur with arbuscular mycorrhizal fungi. The functional significance of MFRE in plant nutrition remains under-explored, particularly their role in plant N assimilation from the variety of sources typically found in soils. C_LIO_LIUsing four 15N-labelled N sources to track N transfer between MFRE and Plantago lanceolata, applied singly and in tandem, we investigated N source discrimination, preference, and transfer to host plants by MFRE. We traced movement of 14C from plants to MFRE to determine the impact of N source type on plant C allocation to MFRE. C_LIO_LIWe found MFRE preferentially transferred N derived from glycine and ammonium to plant hosts over that derived from nitrate and urea, regardless of other N sources present. MFRE mycelium supplied with glycine and ammonium contained more plant-derived carbon than those supplied with other N sources. C_LIO_LIWe show that MFRE directly assimilates and metabolises organic compounds, retaining C to meet its own metabolic requirements and transferring N to plant hosts. Our findings highlight diversity in function of endomycorrhizal associations with potentially profound implications for our understanding of the physiology and ecology of plant-fungal symbioses. C_LI

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Howard, N. O. A., Williams, A., Durant, E., Pressel, S., Daniell, T. J., Field, K. J.. 2024-08-01. Preferential assimilation, metabolism, and transfer of organic nitrogen to host plants by Mucoromycotina 'fine root endophytes'. https://doi.org/10.1101/2024.07.31.606011

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