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| Titel |
Microbiome change by symbiotic invasion in lichens |
| VerfasserIn |
Stefanie Maier, Mats Wedin, Samantha Fernandez-Brime, Bodil Cronholm, Martin Westberg, Bettina Weber, Martin Grube |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250134723
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| Publikation (Nr.) |
 EGU/EGU2016-15474.pdf |
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| Zusammenfassung |
| Biological soil crusts (BSC) seal the soil surface from erosive forces in many habitats
where plants cannot compete. Lichens symbioses of fungi and algae often form
significant fraction of these microbial assemblages. In addition to the fungal symbiont,
many species of other fungi can inhabit the lichenic structures and interact with
their hosts in different ways, ranging from commensalism to parasitism. More than
1800 species of lichenicolous (lichen-inhabiting) fungi are known to science. One
example is Diploschistes muscorum, a common species in lichen-dominated BSC that
infects lichens of the genus Cladonia. D. muscorum starts as a lichenicolous fungus,
invading the lichen Cladonia symphycarpa and gradually develops an independent
Diploschistes lichen thallus. Furthermore, bacterial groups, such as Alphaproteobacteria and
Acidobacteria, have been consistently recovered from lichen thalli and evidence is rapidly
accumulating that these microbes may generally play integral roles in the lichen
symbiosis.
Here we describe lichen microbiome dynamics as the parasitic lichen D. muscorum takes
over C. symphycarpa. We used high-throughput 16S rRNA gene and photobiont-specific ITS
rDNA sequencing to track bacterial and algal transitions during the infection process, and
employed fluorescence in situ hybridization to localize bacteria in the Cladonia and
Diploschistes lichen thalli. We sampled four transitional stages, at sites in Sweden and
Germany: A) Cladonia with no visible infection, B) early infection stage defined by the first
visible Diploschistes thallus, C) late-stage infection with parts of the Cladonia
thallus still identifiable, and D) final stage with a fully developed Diploschistes
thallus,
A gradual microbiome shift occurred during the transition, but fractions of Cladonia-associated
bacteria were retained during the process of symbiotic reorganization. Consistent
changes observed across sites included a notable decrease in the relative abundance of
Alphaproteobacteria with a concomitant increase in Betaproteobacteria. Armatimonadia,
Spartobacteria and Acidobacteria also decreased during the infection of Cladonia by
Diploschistes. The lichens differed in photobiont specificity. C. symphycarpa was associated
with the same algal species at all sites, but D. muscorum had a flexible strategy with different
photobiont combinations at each site. This symbiotic invasion system suggests that partners
can be reorganized in BSC and selected for maintaining potential roles rather than depending
on particular species. |
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