title: Changes in the root-associated fungal communities along a primary succession gradient analysed by 454 pyrosequencing.
abstract: We investigated changes in the root-associated fungal communities associated with the ectomycorrhizal herb Bistorta vivipara along a primary succession gradient using 454 amplicon sequencing. Our main objective was to assess the degree of variation in fungal richness and community composition as vegetation cover increases along the chronosequence. Sixty root systems of B. vivipara were sampled in vegetation zones delimited by dated moraines in front of a retreating glacier in Norway. We extracted DNA from rinsed root systems, amplified the ITS1 region using fungal-specific primers and analysed the amplicons using 454 sequencing. Between 437 and 5063 sequences were obtained from each root system. Clustering analyses using a 98.5% sequence similarity cut-off yielded a total of 470 operational taxonomic units (OTUs), excluding singletons. Between eight and 41 fungal OTUs were detected within each root system. Already in the first stage of succession, a high fungal diversity was present in the B. vivipara root systems. Total number of OTUs increased significantly along the gradient towards climax vegetation, but the average number of OTUs per root system stayed unchanged. There was a high patchiness in distribution of fungal OTUs across root systems, indicating that stochastic processes to a large extent structure the fungal communities. However, time since deglaciation had impact on the fungal community structure, as a systematic shift in the community composition was observed along the chronosequence. Ectomycorrhizal basidiomycetes were the dominant fungi in the roots of B. vivipara, when it comes to both number of OTUs and number of sequences.
authors.affiliation: Department of Biology, University of Oslo, Oslo, Norway. rakel.blaalid@bio.uio.no
authors.forename: Rakel
authors.initials: R
authors.lastname: Blaalid
authors.forename: Tor
authors.initials: T
authors.lastname: Carlsen
authors.forename: Surendra
authors.initials: S
authors.lastname: Kumar
authors.forename: Rune
authors.initials: R
authors.lastname: Halvorsen
authors.forename: Karl Inne
authors.initials: KI
authors.lastname: Ugland
authors.forename: Giovanni
authors.initials: G
authors.lastname: Fontana
authors.forename: Håvard
authors.initials: H
authors.lastname: Kauserud
mesh_terms: D001487:Basidiomycota / Q000145:classification / Q000235:genetics*; D004271:DNA, Fungal / Q000032:analysis*; D021903:DNA, Ribosomal Spacer / Q000032:analysis; D017753:Ecosystem; D046448:Ice Cover; D038821:Mycorrhizae / Q000235:genetics; D009664:Norway; D018517:Plant Roots / Q000382:microbiology*; D019664:Polygonaceae / Q000382:microbiology*; D017422:Sequence Analysis, DNA / Q000379:methods*; D013045:Species Specificity
chemical_list: D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer