Integrating novel culturing and culture-independent methods to unveil soil fungal dark matter, functional guilds and environmental drivers across Robinson Ridge, East Antarctica.

Global fungal diversity is estimated to range in the millions, yet it remains severely underexplored, especially in extreme environments. Fewer than 5% of species have been officially identified and characterised. Estimates suggest that 70%-90% of soil fungi remain uncultivable, often referred to as 'fungal dark taxa'. This study shows a comprehensive assessment of the fungal diversity in Robinson Ridge, East Antarctica using both culturing and non-culture dependent methods. The soil community was assessed by ITS gene sequencing of 93 subsoil and 93 surface soils collected along 3 × 300 m long transects. Strains were isolated from soil following enrichment cultivation under oligotrophic conditions supplemented with excess hydrogen gas. Landscape heterogeneity significantly influenced the composition, diversity, and functionality of the communities. A high relative abundance of lichen-associated fungi was recorded in areas with low levels of nutrients and moisture. One hundred and thirty fungal strains were isolated, mainly comprising the classes Eurotiomycetes and Dothideomycetes. A large proportion of fungal ASVs were not shared between techniques, with an overlap of only 1.9% of the total produced sequences. Our study underscores the value of integrating culture-dependent and independent approaches to gain a more comprehensive understanding of fungal distribution, diversity, and functional potential.