Preferential nitrogen and carbon exchange dynamics in Mucoromycotina "fine root endophyte"-plant symbiosis.

Mucoromycotina "fine root endophyte" (MFRE) fungi are an understudied group of plant symbionts that regularly co-occur with arbuscular mycorrhizal fungi. The functional significance of MFRE in plant nutrition remains underexplored, particularly their role in plant nitrogen (N) assimilation from the variety of sources typically found in soils. Using four N-labeled 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.