Biogeographical diversity of plant associated microbes in arcto-alpine plants

• Main Author: Kumar, Manoj Gopala Krishnan
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Rijksuniversiteit Groningen 2016
• Subjects: Arctic; Kilpisjärvi; Ny-Ålesund; Ny Ålesund; Oxyria digyna; Saxifraga oppositifolia
• Online Access: http://hdl.handle.net/11370/f50b2750-96d1-4201-8603-4a7bc2441e14; https://research.rug.nl/en/publications/biogeographical-diversity-of-plant-associated-microbes-in-arctoalpine-plants(f50b2750-96d1-4201-8603-4a7bc2441e14).html; https://pure.rug.nl/ws/files/37363432/Title_and_contents_.pdf; https://pure.rug.nl/ws/files/37363434/Chapter_1.pdf; https://pure.rug.nl/ws/files/37363436/Chapter_2.pdf; https://pure.rug.nl/ws/files/37363438/Chapter_3.pdf; https://pure.rug.nl/ws/files/37363440/Chapter_4.pdf; https://pure.rug.nl/ws/files/37363442/Chapter_5.pdf; https://pure.rug.nl/ws/files/37363444/Chapter_6.pdf; https://pure.rug.nl/ws/files/37363446/Summary_Uittreksel.pdf; https://pure.rug.nl/ws/files/37363448/Acknowledgements.pdf; https://pure.rug.nl/ws/files/37363450/Author_Affiliations.pdf

Terrestrial plants and microbes have co-evolved since the emergence of the former on Earth. Associations with microorganisms can be either beneficial or detrimental for plants. Microbes can be found in the soil surrounding the plant roots, but also in all plant tissues, including seeds. In arcto-alpine regions, plants face extraordinary challenges, and, although we know a lot about their growth and survival strategies, less is known about their microbiomes. Here, I investigated the diversity of microbes associated with two pioneer arcto-alpine plants, Oxyria digyna and Saxifraga oppositifolia, from three geographical regions: Mayrhofen, Austria (alpine climate), Kilpisjärvi, Finland (low-arctic climate) and Ny-Ålesund (high-arctic climate). Compartment (bulk soil, rhizosphere soil, endosphere) influenced the diversity and community structures of both fungi and bacteria. The endophytic communities had the lowest diversity and their community structures were different from those of the bulk and rhizosphere soils. Geographic region significantly influenced the bacterial and diazotrophic communities in the bulk soils, but had weaker impact on bulk soil fungal communities, which were primarily shaped by soil pH. The fungal and diazotrophic endosphere communities were also influenced by region, whereas the total endosphere bacterial communities responded to a lesser extent. The bacterial community structures in the endosphere were influenced by plant species. The plant species act as effective ‘filters’, selecting a restricted set of microbes as endophytes from the highly diverse soil communities across three geographic regions. Most of these key taxa in the endosphere bacteriomes may play a role in nitrogen acquisition in these low-nitrogen environments.