Detection of arbuscular mycorrhizal fungal spores in the air across different biomes and ecoregions

• The role of wind dispersal of spores for arbuscular mycorrhizal (AM) fungi is largely unknown.
• Here, the frequency of AM fungal spores in the soil and air was determined in 18 North American ecoregions.
• AM fungal spores were found in high abundance in the soil, however they were rarely found in the air.
• Only Glomus was found in the air, whereas spores in the soil were taxomomically more diverse.
• Spores were more frequent in the air of arid systems. However, the air is not likely a major mode of dispersal for AM fungi.

Aerial dispersal of fungal spores is common, but the role of wind and air movement in dispersal of spores of arbuscular mycorrhizal (AM) fungi is largely unknown. Several studies have examined the possibility of AM fungal spores being moved by wind vectors without observing spores taken from the air environment. For the first time this study observed the presence of AM fungal spores in the air. The frequency of AM fungal spores in the air was determined in six North American biomes composed of 18 ecoregions. Multiple samples were taken from both the air and the soil at each location. AM fungal spores were found in high abundance in the soil (hundreds of spores per gram of soil), however, they were rarely found in the air (most samples contained no AM fungal spores). Furthermore, only the Glomus morphotype was found in the air, whereas spores in the soil were taxomomically more diverse (Glomus, Acaulospora, Gigaspora, Scutellospora morphotypes were observed). The proportion of Glomus spores in the air relative to Glomus spores in the soil was highest in more arid systems, indicating that AM fungi may be more likely to be dispersed in the air in such systems. Nonetheless, the results indicate that the air is not likely a dominant mode of dispersal for AM fungi.