Contribution of leaf surface fungi to the air spora

Abstract

High concentrations of airborne fungal spores frequently occur from spring through fall in temperate areas of the world. Although it is generally assumed that fungi on leaf surfaces are contributors to the air spora, little data are available comparing the types of fungi found on leaf surfaces with those in the atmosphere. Air sampling was carried out with a Burkard Spore Trap located on the roof of a building on the University of Tulsa campus using standard methods. Leaf samples were aseptically collected from Ulmus americana and Quercus palustris trees on campus, placed in sterile plastic bags, and brought to the lab. For each leaf, 4 cm 2 areas of both upper and lower leaf surfaces were swabbed and plated on malt extract agar with streptomycin. Cultures were incubated at room temperature for 5-7 days and then examined microscopically. Results were expressed as colony forming units (CFU)/cm 2 . Twenty-one fungal taxa were identified from the air samples. The most abundant taxa were Cladosporium, ascospores, basidiospores, and Alternaria; together these four spore types comprised over 90% of the yearly total. Yeasts were the most abundant fungi isolated from both leaf types. Among the mycelial fungi were Phoma species, followed by Cladosporium and Alternaria. Overall twenty genera of filamentous fungi were identified. Yeasts and Phoma are normally splash dispersed and were not identified in the Burkard air samples. However, 10 taxa isolated from leaf surfaces were registered in air samples. Crude estimates of the leaf surface area of each tree suggest that the total fungal load was approximately 5.04Â10 8 CFU for Ulmus and 2.71Â10 8 CFU for Quercus. Of these levels, 19% were from fungi also detected in air samples. The data suggest that some leaf-surface fungi are major contributors to the air spora.

Global fungal spore emissions, review and synthesis of literature data

“…(Davies et al, 1963;Hamilton, 1959;Rodríguez-Rajo et al, 2005;Oliveira et al, 2009;Mallo et al, 2010;Levetin and Dorsey, 2006;Herrero et al, 2006;Wu et al, 2004;Stepalska and Wolek, 2009;Kasprzyk and Worek, 2006;Sakiyan and Inceoglu, 2003). Among these, mostly models from Lanzoni (VPPS 2000) (Lanzoni, 2010) or Burkard (Burkard Scientific, 2000) were used.…”

Microbiology and atmospheric processes: research challenges concerning the impact of airborne micro-organisms on the atmosphere and climate

“…High concentrations of air-borne bacteria and fungal spores frequently occur from spring to fall in temperate areas of the world, mainly due to the fact that leaf surfaces are a major source of fungi (Levetin and Dorsey, 2006;Mitakakis et al, 2001) and bacteria (Tong and Lighthart, 2000) in the air. The higher concentrations of bacteria observed in the summer (JulyAugust) over two agricultural sites in Oregon (USA) may reflect the flux from agricultural sources and activities and dry dusty soil conditions at this time of the year (Tong and Lighthart, 2000).…”

Cladosporiumairborne spore incidence in the environmental quality of the Iberian Peninsula

“…Since many Cladosporium species grow on the phylloplane of different plant species (Levetin & Dorsey, 2006), the wash-out effect of rain in this micro-environment may also prompt a drop in airborne spore concentrations. In general, lower spore concentrations can therefore be expected in locations with greater rainfall.…”