title: Spatial segregation and aggregation of ectomycorrhizal and root-endophytic fungi in the seedlings of two Quercus species.
abstract: Diverse clades of mycorrhizal and endophytic fungi are potentially involved in competitive or facilitative interactions within host-plant roots. We investigated the potential consequences of these ecological interactions on the assembly process of root-associated fungi by examining the co-occurrence of pairs of fungi in host-plant individuals. Based on massively-parallel pyrosequencing, we analyzed the root-associated fungal community composition for each of the 249 Quercus serrata and 188 Quercus glauca seedlings sampled in a warm-temperate secondary forest in Japan. Pairs of fungi that co-occurred more or less often than expected by chance were identified based on randomization tests. The pyrosequencing analysis revealed that not only ectomycorrhizal fungi but also endophytic fungi were common in the root-associated fungal community. Intriguingly, specific pairs of these ectomycorrhizal and endophytic fungi showed spatially aggregated patterns, suggesting the existence of facilitative interactions between fungi in different functional groups. Due to the large number of fungal pairs examined, many of the observed aggregated/segregated patterns with very low P values (e.g., < 0.005) turned non-significant after the application of a multiple comparison method. However, our overall results imply that the community structures of ectomycorrhizal and endophytic fungi could influence each other through interspecific competitive/facilitative interactions in root. To test the potential of host-plants' control of fungus-fungus ecological interactions in roots, we further examined whether the aggregated/segregated patterns could vary depending on the identity of host plant species. Potentially due to the physiological properties shared between the congeneric host plant species, the sign of hosts' control was not detected in the present study. The pyrosequencing-based randomization analyses shown in this study provide a platform of the high-throughput investigation of fungus-fungus interactions in plant root systems.
authors.affiliation: Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Sato
authors.affiliation: National Research Institute of Fisheries Science, Fisheries Research Agency, Yokohama, Japan.
authors.forename: Akifumi S
authors.initials: AS
authors.lastname: Tanabe
authors.affiliation: Network center of Forest and Grassland Survey in Monitoring Sites 1000 Project, Japan Wildlife Research Center, c/o Filed Science Center for Northern Biosphere, Hokkaido University, Tomakomai, Japan.
authors.forename: Amane
authors.initials: A
authors.lastname: Hidaka
authors.affiliation: Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
authors.forename: Kohmei
authors.initials: K
authors.lastname: Kadowaki
authors.affiliation: Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Toju
mesh_terms: D004463:Ecology; D060026:Endophytes / Q000502:physiology*; D065928:Forests; D005658:Fungi / Q000502:physiology*; D007564:Japan; D038821:Mycorrhizae / Q000502:physiology*; D018517:Plant Roots / Q000382:microbiology* / Q000502:physiology; D029963:Quercus / Q000382:microbiology* / Q000502:physiology; D036226:Seedlings / Q000382:microbiology