Sebacinales community structure in roots and soils along land use gradients of the German Biodiversity Exploratories

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Understanding the effects of plant-soil fungal interactions in natural and managed plant communities is of special importance given the increasing awareness that soil biota play a crucial role in plant community assembly and ecosystem functioning. The fungal order of the Sebacinales (Basidiomycota) was recently shown to be present as symptomless endophytes in roots of a vast number of land plants globally by DNA based methods. Despite this wide distribution, very little is know about the ecology of these endophytic Sebacinales, their community structure, and how it is affected by plant community composition and components of land use. This is potentially due to their low abundance in plant roots, which make the application of recently published specific PCR primers necessary.Published data and our preliminary work suggests that Sebacinales communities within one root fragment are very species poor. However, this finding might also be a methodological artifact of the Sanger sequencing applied. We will therefore apply massive parallel sequencing (454 sequencing) on a small set of samples to test whether we can verify these findings.Published systematic diversity assessments of endophytic Sebacinales are still extremely scarce and links between their community composition, environmental factors and host plant characteristics are largely unknown. Due to the large amount of organismic diversity and soil data collected on plot basis, the Biodiversity Exploratories would be ideal to unravel these links. We propose to analyze Sebacinales communities in representative root samples from each grassland EP. Community data will be analyzed for relationships with land use, soil and plant community characteristics. We expect strong effects of soil parameters like pH, negative effects on richness by increasing land use intensity and weak effects of host plant community composition due to low host specificity. Due to the lack of information on the soil phase of Sebacinales, its richness, diversity and factors potentially shaping those attributes, we propose to study Sebacinales communities from soil samples from all grassland EP taken in parallel to the root samples. We will test the hypothesis that Sebacinales fungi found in the soil are in fact the "biological reservoir" for Sebacinales found in the root, indicating the soil phase as the major dispersal pathway. We will also test for effects of land use, soil properties and plant community composition on the Sebacinales communities found in the soil. Knowledge on the soil phase of Sebacinales will have huge implications for the understanding of Sebacinales ecology and soil fungal ecology in general. Due to their seemingly low host specificity, Sebacinales could be important in forming common fungal networks between plant species which can have profound consequences for plant communities, e.g. in terms of plant-plant communication.