Microcosm-based analyses of Scots pine seedling growth, ectomycorrhizal fungal community structure and bacterial carbon utilization profiles in boreal forest humus and underlying illuvial mineral horizons

• Published in: FEMS microbiology ecology 2001-06, Vol.36 (1), p.73-84
• Main Authors: Heinonsalo, J, Jorgensen, K.S, Sen, R
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; B horizons; Bacteria; Bacterial carbon utilization; bacterial communities; Biochemistry and biology; Biological and medical sciences; Boreal forests; Carbon; Carbon sources; Carboxylic acids; Cenococcum geophilum; Chemical, physicochemical, biochemical and biological properties; Cluster analysis; Colonization; Community structure; Decomposing organic matter; Ecology; ectomycorrhizae; Ectomycorrhizas; Evergreen trees; Forests; Fundamental and applied biological sciences. Psychology; fungal communities; Fungi; Horizon; Humus; internal transcribed spacers; ITS‐RFLP; Microbial ecology; Microbiology; multivariate analysis; mycelium; Mycorrhizal fungus; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Pine trees; Pinus sylvestris; Podzol; restriction fragment length polymorphism; Rhizosphere; rhizosphere fungi; ribosomal DNA; Roots; Russula; Scots pine; seedling growth; Seedlings; Soil; soil bacteria; Soil science; Soil types; Species; Suillus; Suillus bovinus; Suillus variegatus; Taiga; Thelephora terrestris; Utilization
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2001.tb00827.x

We report on the identity of indigenous mycorrhiza forming fungi and rhizosphere/mycorrhizosphere bacterial community carbon source utilization profiles of Scots pine (Pines sylvestris L.) seedlings grown in boreal forest humus (O) or illuvial (B) mineral horizon containing microcosm growth systems. Based on rDNA (ITS)-RFLP analyses, a total of 10 fungal RFLP taxa were identified from pre-morphotyped mycorrhizas on 7-month-old seedling roots. Hierarchical cluster analysis, including corresponding RFLPs of known fungal species, confirmed root colonization by eight mycorrhizal species. In the O horizon, roots were colonized by e.g. Suillus bovinus, Suillus variegatus, Cenococcum geophilum, Piloderma croceum, Thelephora terrestris and Russula vinicolor. Mycobiont diversity in the mineral B horizon was lower but included Piceirhiza bicolorata and both Suillus species which produced extensive extramatrical mycelium. In comparison to non-colonized soils, rhizosphere and mycorrhizosphere compartments supported significantly higher numbers of bacteria (mean range 10(8)-10(11) cells g(-1) fresh weight (fw)). Specific rhizosphere/mycorrhizosphere 'niche'-linked bacterial communities were detected following multivariate analyses (PCA and CA) of bacterial carbon utilization profiles (Biolog GN microplate). Distinct preferences for amino and carboxylic acids were identified in mineral B horizon rhizospheres whereas a wider range of carbon sources were utilized in the fungal-dominated mycorrhizospheres irrespective of soil types.