Fungal and bacterial community responses to Suillus variegtus extraradical mycelia and soil profile in Scots pine microcosms
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To investigate the importance of ectomycorrhizal (ECM) extraradical mycelia and soil substrate in shaping specific mycorrhizosphere microbial communities.
Suillus variagtus inoculated Scots pine seedlings were grown for approximately 5 months in soil microcosms using five soil layer treatments. Fungal and bacterial community composition near roots, in hyphal fronts and ‘bulk soil’ was studied using T-RFLP, cloning and sequencing. Plant chemistry at harvest and initial chemical properties for the soil layers were analysed.
Both fungal and bacterial community compositions differed between different soil layers for S. variegatus inoculated seedlings. The mixed soil, corresponding to the interface between organic and mineral layers, supported the highest plant and fungal biomass and the most diverse fungal communities. Environmental variables explained ca. 50 % of the variation in data. In OE mixed layers the main driver shaping communities was plant chemistry, reflecting belowground C flow, and for O and E layers soil chemistry (nutrients and pH) was the main driver. Fungal communities included 56 identified taxa, and more taxa were found in soil associated with hyphal fronts compared to ‘bulk soil’ and roots. Bacterial communities changed over time and bacteria associated with hyphal fronts partly differentiated from other sampling sites.
The experimental microcosm setup allowed establishment of communities reflecting those naturally occurring at the field site. Given that belowground C flow is sufficient, extraradical mycelial expansion in the substrate has the potential to drive microbial community development.
KeywordsMicrobial communities T-RFLP Pinus sylvestris ITS and 16S rRNA Soil horizon Ectomycorrhizal
We would like to thank the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) and The Royal Swedish Academy of Agriculture and Forestry (KSLA) for financial support. We thank Katarina Ihrmark for reading and commenting on the manuscript, and greatly appreciate the work done by the referees in providing feedback on the manuscript.
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