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.

与丛枝菌根（AMF）和毛霉菌“细根内生植物”（MFRE）真菌相关的非维管植物，在大气[CO ₂ ]（a [CO ₂ ]）高于环境的条件下，从其真菌同伴中获得了更大的收益。然而，关于α[CO ₂ ]的变化如何影响维管植物中MFRE功能的信息尚不清楚。我们在环境和升高的环境下，使用³³ P-正磷酸盐，¹⁵  N-氯化铵和¹⁴ CO ₂同位素示踪剂测量了无节藻植物番茄无毛藻和毛霉菌细根内生真菌之间磷（P），氮（N）和碳（C）的运动。a [CO ₂浓度分别为440和800 ppm。转让³³ P和¹⁵ 至植物n在MFRE不受影响通过在[CO变化₂ ]。在升高的a [CO ₂ ]下，从植物向MFRE的碳转移略有增加。我们的结果表明，维管束植物和毛壁藻FRE之间的C-养分交换在很大程度上不受a [CO ₂ ]变化的影响。弄清MFRE在宿主植物营养中的作用以及在不同的非生物条件下共生体之间潜在的C-N贸易变化，对于进一步了解植物-真菌共生体在生态系统中的过去，现在和未来的作用势在必行。