Global richness of arbuscular mycorrhizal fungi

Arbuscular mycorrhizal (AM) fungi form mutualistic associations with most land plants and are of pivotal importance for plant growth and nutrition. AM fungi include both the well-known phylum Glomeromycota (G-AMF) and the recently established clade of Endogonomycete fine root endophytes within the phylum Mucoromycota, often viewed as putative AMF (E-AMF). Yet, the global richness of these fungal groups, in particular of E-AMF, is poorly understood. To provide comprehensive global species of G-AMF and E-AMF, we analysed long-read sequencing data of the full-length ITS marker from 4,733 sampling sites across all continents and biomes. Our study provides the first combined estimate of global G-AMF and putative E-AMF richness, far exceeding the numbers and taxa reported so far. Specifically, we detected 8,517 OTUs of G-AMF, surpassing previous AMF richness estimates by a factor of five to fifteen. In addition, we identified 600 OTUs for putative E-AMF, providing the first global estimate for this group.