Sebacinales distribution patterns in plant communities
Zusammenfassung der Projektergebnisse
The Sebacinales is a widely distributed and phylogenetically diverse lineage within the Basidiomycota with a unique diversity of nutritional modes. At the beginning of our project, it was clear that the patterns of geographic distribution of Sebacinales are not linked to co-evolutionary processes or host specificity, therefore, new additional data was needed to better understand the factors influencing their current patterns of geographic distribution and the phylogenetic relationships. To address these questions, we analysed a dataset comprising 264 ITS+5.8S+D1/D2 rDNA sequences from 456 samples of plant thalli or roots collected from eight vegetation communities along an altitudinal gradient in the Bavarian Alps. To enhance our original proposal, we assembled an additional dataset of 128 ITS+5.8S+D1/D2 rDNA sequences from roots/thalli of European plant specimens, and all available D1/D2 rDNA sequences available from GenBank to show that members of the Sebacinales are not extremely versatile in their mycorrhizal associations, but that they are widely present as symptomless endophytes. A dataset of 156 new rDNA sequences spanning the ITS+5.8S+D1D2 regions was generated frorn herbaceous plants collected in grassland and agricultural habitats to address three questions: i) What is the diversity of endophytic Sebacinales in the roots of herbaceous plants in agricultural and grassland ecosystems; ii) Is the diversity and composition of endophytic sebacinoid communities influenced by land use/plant community, and iii) Does the newly isolated Serendipita herbamans has phenotypical effects on selected herbaceous plants. A dataset of 340 DNA haplotype sequences from nuclear (ITS+5.8S+D1/D2 and RPB2) and mitochondrial (ATP6) gene regions was generated for 98 population samples of the morphospecies S. epigaea and S. incrustans collected over a regional geographic range. This data was used to explore intraspecific genetic variation, to determine if the intraspecific nuclear and mitochondrial genealogies are concordant, and if significant genetic diversity is linked to morphological, geographic and/or ecological characteristics? In addition, we used 120 D1/D2 rDNA sequences generated in our project and all available D1/D2 rDNA sequences from GenBank, to conduct a taxonomic reordenation within the Sebacinales. Finally, we used nuclear (18S, 28S, RPBl) and mitochondrial (ATP6) sequences from 97 Basidiomycota species and three Ascomycota species, and 2661 ITS sequences and a subset of 693 ITS sequences from the Sebacinales to infer diversity patterns, phylogenetic structure and divergence times of Sebacinales with respect to their nutritional lifestyles by integrating data from fossil- and secondary-calibrated phylogenetic analyses. Analyses from these datasets indicate that Sebacinales is a widely distributed and relatively old lineage within Basidiomycota evolution, however, major diversifications within the order are most likely not the result of vicariance events. Some major diversifications in the Sebacinales coincide with the diversifications of their host plants, whereas other are rather younger than their hosts. The high genetic diversity detected in the Sebacinales reinforces observations from previous studies and also underscores a high degree cryptic diversification. At local scales, we found that some sebacinoid communities are structured by extreme soil conditions and land use. The following taxonomic novelties were introduced: three new genera, nine new combinations and three new species were described. The high intraspecific genetic diversity within the morphospecies Sebacina epigaea and S. incrustans was mainly linked to natural recombination events and synonymous mutations. There are no general patterns explaining the current distribution and composition of Sebacinales. The ITS + 5.8S + D1/D2 regions of the rDNA contain significant genetic variation that resolve lower and higher relationships across the Sebacinales, whereas the ITS region was useful for discriminating among populations. We propose the ITS region as a potentially useful DNA segment for barcoding in the Sebacinales. All our studies also indicate that Sebacinales is a highly diverse and widely spread lineage, but of the low abundance in terrestrial ecosystems. A combination of appropriate molecular genetic markers, accurate ecological documentation and morphological examinations provide a better understanding of the diversity, geographic distribution and ecological role of Sebacinales. Finally, the taxonomic ordination conducted in this project should allow for better identification of environmental samples and description of new species. Future studies at different spatial scales are needed to investigate why Sebacinales were more frequently detected in some plant families than others, and why they were detected only by PCR and not by transmission electron microscopy.
Projektbezogene Publikationen (Auswahl)
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(2011). A clustering optimization strategy to estimate species richness of Sebacinales in the tropical Andes based on molecular sequences from distinct DNA regions. Biodiversity and Conservation 21 : 2269-2285
Setaro S, Garnica S, Herrera PI, Suarez JP, Göker M
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(2011). Sebacinales everywhere; previously overlooked ubiquitous fungal endophytes. PLoS ONE 6(2):e16793
Weiß M, Sykorova Z, Garnica S, Riess K, Martos F, Krause C, Oberwinkler F, Bauer R, Redecker D
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(2013). Enigmatic Sebacinales. Mycological Progress 12:1-27
Oberwinkler F, Riess K, Bauer R, Weiß M, Selosse J, Garnica S, Zuccaro A
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(2013). High genetic diversification at the regional scale and possible speciation in Sebacina epigaea and S. incrustans. BMC Evolutionary Biology 13:102
Riess K, Bauer R, Oberwinkler F, Garnica S
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(2013). Phylogenetic diversity and structure of sebacinoid fungi associated with plant communities along an altitudinal gradient. FEMS Microbiology Ecology 82:265-278
Garnica S, Riess K, Bauer R, Oberwinkler F, Weiß M
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(2014). Communities of endophytic Sebacinales associated with roots of herbaceous plants in agricultural and grassland ecosystems are dominated by Serendipita herbamans sp. nov. PLoS ONE 9(4): e94675
Riess K, Oberwinkler F, Bauer R, Garnica S
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(2014). Morphology and molecules: the Sebacinales, a case study. Mycologicat Progress 13: 445-470
Oberwinkler F, Riess K, Bauer R, Garnica S
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Divergence times and phylogenetic patterns of Sebacinales, a highly diverse and widespread fungal lineage. PLoS ONE 11(3): e0149531
Garnica S, Riess K, Schön M-E, Oberwinkler F, Setaro S
