Carbon for nutrient exchange between Lycopodiella inundata and Mucoromycotina fine root endophytes is unresponsive to high atmospheric CO2

Abstract

Non-vascular plants associating with arbuscular mycorrhizal (AMF) and Mucoromycotina ‘fine root endophyte’ (MFRE) fungi derive greater benefits from their fungal associates under higher atmospheric [CO2] (a[CO2]) than ambient; however, nothing is known about how changes in a[CO2] affect MFRE function in vascular plants. We measured movement of phosphorus (P), nitrogen (N) and carbon (C) between the lycophyte Lycopodiella inundata and Mucoromycotina fine root endophyte fungi using 33P-orthophosphate, 15 N-ammonium chloride and 14CO2 isotope tracers under ambient and elevated a[CO2] concentrations of 440 and 800 ppm, respectively. Transfers of 33P and 15 N from MFRE to plants were unaffected by changes in a[CO2]. There was a slight increase in C transfer from plants to MFRE under elevated a[CO2]. Our results demonstrate that the exchange of C-for-nutrients between a vascular plant and Mucoromycotina FRE is largely unaffected by changes in a[CO2]. Unravelling the role of MFRE in host plant nutrition and potential C-for-N trade changes between symbionts under different abiotic conditions is imperative to further our understanding of the past, present and future roles of plant-fungal symbioses in ecosystems.

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

“…Mucoromycotina is a large subphylum, sister to Glomeromycotina (Schüßler and Walker, 2011), and consists mainly of saprotrophic and pathogenic species (Hoffmann et al, 2013). Mycorrhizal fungi within this subphylum appear to be restricted to the order Endogonales (Hoysted et al, 2023, Hoysted et al, 2019, Hoysted et al, 2021b and are referred to as Mucoromycotina 'fine root endophytes' (MFRE). Like AM fungi, MFRE form associations with a wide range of host plants (Kowal et al, 2020;Albornoz et al, 2021) across diverse habitats, from western Europe (Field et al, 2015) to Australasia (Albornoz et al, 2022), each with varying edaphic factors including moisture (Deng et al, 2020), organic matter (Stockmann et al, 2015) and nutrient status (Zhang et al, 2019).…”

Niche differentiation of Mucoromycotinian and Glomeromycotinian arbuscular mycorrhizal fungi along a 2-million-year soil chronosequence

“…Mucoromycotinian AMF have an ancient relationship with bryophytes (Rimington et al 2018 , 2019 ), which features a traditional mycorrhizal carbon (C)-for-nutrient exchange (Field et al 2015 ; Hoysted et al 2019 , 2021 ). Furthermore, M-AMF can co-occur with G-AMF, suggesting complementary roles in bryophyte hosts (Field et al 2016 , 2019 ).…”

Endorrhizal fungal symbiosis in aroids of the Western Ghats, southern India

“…Fine root endophytes are globally distributed and play vital role in both agricultural and semi-natural habitats, across a wide range of host plants (Field et al, 2015;Orchard et al, 2017). Although the benefit of FRE symbiosis to plants is not well resolved like that for AM association, available evidence indicate that FRE fungi like AM fungi can aid plants in their nutrient acquisition (Hoysted et al, 2021;Howard et al, 2022). Nevertheless, the FRE symbiosis in aroids is not well reported as those for AM fungi (Muthukumar and Karthik, 2021).…”