What's in a name? The case for standardized nomenclature for mutualistic Mucoromycotina ‘fine root endophytes’

Arbuscular mycorrhizal (AM) fungi are a near-ubiquitous group of plant symbiotic fungi and have been the focus of much mycorrhizal research over the last 60 years (Koide and Mosse, 2004). However, a lesser known group of mycorrhizal fungi, the Mucoromycotina ‘fine root endophytes’ (MFRE), have garnered increasing research interest in recent years. This early branching lineage of fungi (Bidartondo et al., 2011; Field et al., 2015) was recently reclassified as belonging to the subphylum Mucoromycotina (Orchard et al., 2017a) rather than the Glomeromycotina which encompasses the AM fungi (or ‘coarse root endophytes’). Considering the rapidly growing interest in fine root endophytes, the use of a consistent nomenclature is becoming an important issue for the research community. Here, we summarize the background literature and recent discussion from the 12th International Conference on Mycorrhiza (ICOM12; 4–9 August 2024, Manchester, UK), proposing a standardized and cohesive terminology for this group of enigmatic, though widespread, endomycorrhizal fungi.