Taxonomic diversity of fungi deposited from the atmosphere

Abstract

Fungi release spores into the global atmosphere. The emitted spores are deposited to the surface of the Earth by sedimentation (dry deposition) and precipitation (wet deposition), and therefore contribute to the global cycling of substances. However, knowledge is scarce regarding the diversities of fungi deposited from the atmosphere. Here, an automatic dry and wet deposition sampler and high-throughput sequencing plus quantitative PCR were used to observe taxonomic diversities and flux densities of atmospheric fungal deposition. Taxon-specific fungal deposition velocities and aerodynamic diameters (da) were determined using a collocated cascade impactor for volumetric, particle-size-resolved air sampling. Large multicellular spore-producing dothideomycetes (da ≥ 10.0 μm) were predominant in dry deposition, with a mean velocity of 0.80 cm s–1 for all fungal taxa combined. Higher taxonomic richness was observed in fungal assemblages in wet deposition than in dry deposition, suggesting the presence of fungal taxa that are deposited only in wet form. In wet deposition, agaricomycetes, including mushroom-forming fungi, and sordariomycetes, including plant pathogenic species, were enriched, indicating that such fungal spores serve as nuclei in clouds, and/or are discharged preferentially during precipitation. Moreover, this study confirmed that fungal assemblage memberships and structures were significantly different between dry and wet deposition (P-test, p < 0.001). Overall, these findings suggest taxon-specific involvement of fungi in precipitation, and provide important insights into potential links between environmental changes that can disturb regional microbial communities (e.g., deforestation) and changes in precipitation patterns that might be mediated by changes in microbial communities in the atmosphere.

Microbial composition in seasonal time series of free tropospheric air and precipitation reveals community separation

“…High wind speed in February yielded the second highest number of genera occurring in one season (31.7%) and the communities were dominated by Agaricomycetes, which is ground and plant associated and known to form propagules being dispersed by the air and mainly connected to wet deposition (Hibbett et al 2014;Prasher 2015). Additionally, compared to the other phyla, they are characterized by a relative small aerodynamic diameter which enables the spores to avoid faster sedimentation by dry deposition (Woo et al 2018) and usually contribute a big share of airborne fungi (Pickersgill et al 2017;Fröhlich-Nowoisky et al 2012). However, it has to be taken in to account that the choosen molecular primer and amplification method can result in an over-or underrepresentation of certain fungal classes (e.g., here highly abundant Agaricomycetes) or phyla (Blaalid et al 2013).…”

“…This might be due to the high abundance of fungi in August, but further also the higher humidity during this time, as fungal species actively discharge spores via liquid jets into the air, preferentially under humid conditions (Pringle et al 2005;Elbert et al 2007) and fungal variability being associated with humidity and rain frequency (Bowers et al 2013). Fungal composition was shown to be significantly different in wet and dry deposition, suggesting taxon and size specific involvement in cloud condensation and precipitation (Woo et al 2018).…”

Plant assemblages in atmospheric deposition

“…Previously collected samples (Woo et al, 2018) were used for this study. Briefly, air and deposition samples were collected on the roof (approximately 20 m above ground level) of a building in a mountainous, forested area of Seoul in South Korea (37°27'55.0"N; 126°57'17.7"E).…”

“…DNA extraction was performed as described previously (Woo et al, 2018). The internal transcribed spacer 2 (ITS2) region was amplified using universal plant-specific primers ITS-p3 and ITS-u4 (Cheng et al, 2016) with adapter sequences for Illumina MiSeq.…”

“…Our previous research showed that fungal assemblages differed significantly between wet and dry deposits, indicating taxon-specific involvement of fungi in precipitation (Woo et al, 2018), and we wished to determine whether plant assemblages displayed similar specificities. In this study, molecular techniques were used to compare the taxonomic compositions and flux densities of plant particles in wet and dry atmospheric deposits.…”