Fungal community composition and diversity vary with soil depths and landscape position in a no-till wheat cropping system

Authors: Schlatter, Daniel; KAHL, KENDALL - University Of Idaho; Carlson, Bryan; Huggins, David; Paulitz, Timothy

Submitted to: FEMS Microbiology Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2018
Publication Date: 5/24/2018
Citation: Schlatter, D.C., Kahl, K., Carlson, B.R., Huggins, D.R., Paulitz, T.C. 2018. Fungal community composition and diversity vary with soil depths and landscape position in a no-till wheat cropping system. FEMS Microbiology Ecology. 94:1-15. https://doi.org/10.1093/femsec/fiy098.
DOI: https://doi.org/10.1093/femsec/fiy098

Interpretive Summary: Fungal communities in soil are critical to plant health and ecosystem processes in agricultural systems, especially in no-till systems. The soils of the Palouse are wind-derived loess and very deep (many feet deep). But little is known about fungal communities in these deeper depths. We looked at fungal communities with next-generations sequencing, and found very distinct differences with depth. Shallow depths had greater richness and diversity of saprotrophs, fungi involved in breaking down the residue. Fungi in deeper depth were less diverse and fewer number of groups, and many had a pathogenic lifestyle or were endophytes in roots.

Technical Abstract: Fungal communities in soil are critical to plant health and ecosystem processes in agricultural systems. Although the composition of fungal communities is often related to soil edaphic characteristic and host plant identity, there is a paucity of information on how communities vary with soil depth and landscape characteristics in no-till cropping systems. The Palouse region of eastern Washington and northern Idaho is dominated by dryland wheat systems and is characterized by a highly variable landscape with steep, rolling hills. As a result, no-till practices are increasingly used to combat soil erosion and conserve soil moisture. In this work, we use high-throughput sequencing of fungal ITS1 amplicons to characterize fungal communities across soil depth profiles (0, 10, 25, 50, 75, and 100 cm from the soil surface) among distinct landscape positions (north-facing, south-facing, bottom- and top-slopes) across a no-till wheat field. Fungal communities were highly stratified with soil depth, where deeper depths harbored distinct fungal taxa and more variable, less diverse fungal communities. Fungal communities from deep soils tended to harbor a greater portion of taxa inferred to have pathotrophic or symbiotrophic in addition to saprotrophic lifestyles. Moreover, co-occurrence networks of fungal taxa became smaller and more dense as soil depth increased. In contrast, differences between fungal communities from north-facing and south-facing slopes were relatively minor, though a small number of taxa tended to prefer a given aspect. Together, these results suggest that upper soil layers harbor highly diverse fungal communities that compete for abundant resources, whereas only a small number of taxa inhabit deeper soil layers where they may rely more on pathotrophic or symbiotrophic strategies to obtain resources, rather than saprotrophic competition. Further, the small differences in fungal communities among landscape positions suggests that management practices, such as wheat cropping or fertilization, overshadow environmental differences due to aspect in selecting for fungal communities.