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Citation for Study 25906

About Citation title: "Phylogenetic diversity of 200+ isolates of the ectomycorrhizal fungus Cenococcum geophilum associated with Populus trichocarpa soils in the Pacific Northwest, USA and comparison to globally distributed representatives.".
About Study name: "Phylogenetic diversity of 200+ isolates of the ectomycorrhizal fungus Cenococcum geophilum associated with Populus trichocarpa soils in the Pacific Northwest, USA and comparison to globally distributed representatives.".
About This study is part of submission 25906 (Status: Published).

Citation

Velez J., Morris R.M., Vilgalys R., Labbe J., & Schadt C. 2020. Phylogenetic diversity of 200+ isolates of the ectomycorrhizal fungus Cenococcum geophilum associated with Populus trichocarpa soils in the Pacific Northwest, USA and comparison to globally distributed representatives. Fungal Diversity, .

Authors

  • Velez J. (submitter) Phone 8655665578
  • Morris R.M.
  • Vilgalys R.
  • Labbe J.
  • Schadt C.

Abstract

The ubiquitous ectomycorrhizal fungus Cenococcum geophilum has been proposed as a model organism for fungal genetic and ecological studies due to its wide-spread association with both gymnosperm and angiosperm plant species, straightforward in vitro cultivation, and species hardiness in response to a number of soil stressors. A sexual stage (teleomorph) is unknown for C. geophilum, which is widely considered to be a complex of several cryptic species since extreme phylogenetic divergence is frequently observed within populations of otherwise morphologically identical strains. An alternative view is that C. geophilum represents a highly outcrossed species which would suggest cryptic sexual states and frequent recombination. Here we describe a new isolate collection of 229 C. geophilum isolates collected from soils under Populus trichocarpa from 123 collection sites spanning a ~283 mile north-south transect in Washington and Oregon, USA (PNW). The identity of each isolate was confirmed by sequencing of the internal transcribed spacer (ITS) rRNA gene region and the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. To further understand the phylogenetic relationships within C. geophilum, we performed maximum likelihood phylogenetic analysis to assess divergence within the PNW isolate collection, as well as a global GAPDH phylogenetic analysis of 789 isolates with publicly available data from the United States, Europe, Japan, and other countries. Phylogenetic analyses of the PNW isolates revealed three distinct phylogenetic groups, with 15 clades that strongly resolved at >80% bootstrap support based on a GAPDH phylogeny and one clade segregating strongly in two principle components analyses. The clades of PNW isolates varied greatly in their abundance and representation across the North-South range, from smaller groups collected in only one location to a monophyletic group of isolates that spanned nearly the entire gradient at ~250 miles. A direct comparison between the GAPDH and ITS phylogenies showed evidence of intra-species recombination within the PNW isolate collection. Additional analyses revealed stark incongruence between the ITS and GAPDH regions, further supporting probable recombination between the PNW isolates. In the global isolate collection phylogeny, 34 clades were strongly resolved at >80% bootstrap support, with some clades representing intra- and intercontinental distributions. These data are highly suggestive of divergence within multiple cryptic species, however additional analyses such as higher resolution genotype-by-sequencing approaches are needed to distinguish potential species boundaries and/or recombination patterns.

Keywords

Cenococcum geophilum; phylogeny; GAPDH; recombination; Populus trichocarpa

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  • Canonical resource URI: http://purl.org/phylo/treebase/phylows/study/TB2:S25906
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