title: Network analysis reveals ecological links between N-fixing bacteria and wood-decaying fungi.
abstract: Nitrogen availability in dead wood is highly restricted and associations with N-fixing bacteria are thought to enable wood-decaying fungi to meet their nitrogen requirements for vegetative and generative growth. We assessed the diversity of nifH (dinitrogenase reductase) genes in dead wood of the common temperate tree species Fagus sylvatica and Picea abies from differently managed forest plots in Germany using molecular tools. By incorporating these genes into a large compilation of published nifH sequences and subsequent phylogenetic analyses of deduced proteins we verified the presence of diverse pools corresponding to functional nifH, almost all of which are new to science. The distribution of nifH genes strongly correlated with tree species and decay class, but not with forest management, while higher fungal fructification was correlated with decreasing nitrogen content of the dead wood and positively correlated with nifH diversity, especially during the intermediate stage of wood decay. Network analyses based on non-random species co-occurrence patterns revealed interactions among fungi and N-fixing bacteria in the dead wood and strongly indicate the occurrence of at least commensal relationships between these taxa.
authors: Department of Soil Ecology, UFZ - Helmholtz Centre for Environmental Research, Halle (Saale), Germany ; Institute of Silviculture, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg i. Brsg., Germany.
authors: Björn
authors: B
authors: Hoppe
authors: Institute of Silviculture, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg i. Brsg., Germany.
authors: Tiemo
authors: T
authors: Kahl
authors: Pilzteam Bayern, Hohenau, Germany.
authors: Peter
authors: P
authors: Karasch
authors: Department of Soil Ecology, UFZ - Helmholtz Centre for Environmental Research, Halle (Saale), Germany ; The German Centre for Integrative Biodiversity Research (iDiv), University Leipzig, Leipzig, Germany.
authors: Tesfaye
authors: T
authors: Wubet
authors: Institute of Silviculture, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg i. Brsg., Germany.
authors: Jürgen
authors: J
authors: Bauhus
authors: Department of Soil Ecology, UFZ - Helmholtz Centre for Environmental Research, Halle (Saale), Germany ; Institute of Biology I, University of Leipzig, Leipzig, Germany ; The German Centre for Integrative Biodiversity Research (iDiv), University Leipzig, Leipzig, Germany.
authors: François
authors: F
authors: Buscot
authors: Department of Soil Ecology, UFZ - Helmholtz Centre for Environmental Research, Halle (Saale), Germany.
authors: Dirk
authors: D
authors: Krüger
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000737:chemistry / Q000201:enzymology / Q000302:isolation & purification; D018407:Bacterial Physiological Phenomena; D017037:Dinitrogenase Reductase / Q000737:chemistry / Q000235:genetics; D004463:Ecology; D029964:Fagus / Q000382:microbiology*; D005658:Fungi / Q000302:isolation & purification / Q000502:physiology*; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010802:Phylogeny; D028222:Picea / Q000382:microbiology*; D014934:Wood / Q000382:microbiology*
chemical_list: D017037:Dinitrogenase Reductase