Vertical distribution of fungal communities in tallgrass prairie soil

Abstract

We used 454 sequencing of the internal transcribed spacer region to characterize fungal communities in tallgrass prairie soils subdivided into strata 0–10, 10–20, 30–40 and 50–60 cm deep. The dataset included more than 14 000 fungal sequences distributed across Basidiomycota, Ascomycota, basal fungal lineages and Glomeromycota in order of decreasing frequency. As expected the community richness and diversity estimators tended to decrease with increasing depth. Although species richness was significantly reduced for samples from the deeper profiles, even the deepest stratum sampled contained richness of more than a third of that in the topmost stratum. More importantly, nonparametric multidimensional scaling (NMS) ordination analyses indicated that the fungal communities differed across vertical profiles, although only the topmost and deepest strata were significantly different when the NMS axis scores were compared by ANOVA. These results emphasize the importance of considering the fungal communities across the vertical strata because the deeper soil horizons might maintain a distinct community composition and thus contribute greatly to overall richness. The majority of operational taxonomic units (OTUs) declined in frequency with increasing depth, although a linear regression analysis indicated that some increased with increasing depth. The OTUs and BLAST-assigned taxa that showed increasing frequencies were mainly unculturable fungi, but some showed likely affinities to families Nectriaceae and Venturiaceae or to genus Pachnocybe. Although the ecological roles of the fungi in the deeper strata remain uncertain, we hypothesize that the fungi with preferences for deeper soil have adequate access to substrates and possess environmental tolerances that enable their persistence in those environments.

• 454 sequencing
• pyrosequencing
• soil depth
• soil fungi
• tallgrass prairie

This research was financially supported by Kansas State University, Division of Biology (BRIEF-program), Ecological Genomics Institute (SEED-program) and the U.S. Department of Energy’s Office of Science (BER) through the Midwestern Regional Center of the National Institute for Climatic Change Research at Michigan Technological University. Konza Prairie LTER provided access to the tallgrass prairie sites. We thank Patrick O’Neal, Jeff Taylor and Rose Philips for assistance with collection and processing of soil cores. Lorena Gomez assisted in the sample processing from DNA extraction to 454 sequencing. Regina Shaw, Interdisciplinary Center for Biotechnology Research at University of Florida, performed 454 sequencing at University of Florida Genomics Core Facility.