Microbiology of alpine cushion plants: influence of biotic and abiotic drivers on microbial communities

Microorganisms are key component of Earth biodiversity and ecosystem processes, especially in soils where they interact with plants. The objectives of the PhD was to caracterize the plant and abiotic respective influence on microbial spatial distribution. The work was based on a simplified soil biol...

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Bibliographic Details
Main Author: Roy, Julien
Other Authors: Laboratoire d'Ecologie Alpine (LECA), Université Joseph Fourier - Grenoble 1 (UJF)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), Université de Grenoble, Roberto Geremia
Format: Doctoral or Postdoctoral Thesis
Language:French
Published: HAL CCSD 2014
Subjects:
Online Access:https://theses.hal.science/tel-01141406
https://theses.hal.science/tel-01141406/document
https://theses.hal.science/tel-01141406/file/manuscrit_these_JulienRoy_final.pdf
Description
Summary:Microorganisms are key component of Earth biodiversity and ecosystem processes, especially in soils where they interact with plants. The objectives of the PhD was to caracterize the plant and abiotic respective influence on microbial spatial distribution. The work was based on a simplified soil biology model, the alpine cushion plants. We choose one species composed of variable morphotype, Silene acaulis, an ecosystem engineer species that creates de novo soilthrough growth. Sampling design includes soil within cushions and outside, spanning altitudinal and geological gradients. Molecular approachs were used to describe diversity and to genotype cushions. Cushions structures bacterial and fungal regional beta diversity through a micro-local buffering of the influence of abiotic context, homogeneizing soil pH and by nutrient supply. This engineering effect increased in stressful conditions and varied according to plantgenotype. Betadiversity differed between bacteria and fungi. Bacterial communities are mainly influenced by pH and converge within cushions while fungal communities correlate to cushion genetic, especially plant-associated biotrophs fungal clades. This work shows that plants act as a major biotic filter on microbial biogeography. Les microorganismes occupent une place centrale dans la diversité du vivant et les processus écosystémiques, notamment dans le sol où ils sont en interaction avec les plantes. Cette thèse vise à caractériser l’influence respective des plantes et du contexte abiotique dans la distribution spatiale des microorganismes. Le travail s’appuie sur un modèle simplifié de la biologie des sols, les plantes en coussins des falaises de haute montagne. Nous avons suivi une seule espèce aux morphotypes variés, Silene acaulis, une espèce ingénieure de l’écosystème dont la croissance mène à la création d’un sol de novo. L’échantillonnage comprend le prélèvement de sol de plante et de sol extérieur comme témoin, pour des coussins distribués le long de gradients altitudinaux et ...