Extremotolerant fungi from alpine rock lichens and their phylogenetic relationships

Abstract

Fungi other than the lichen mycobiont frequently co-occur within lichen thalli and on the same rock in harsh environments. In these situations dark-pigmented mycelial structures are commonly observed on lichen thalli, where they persist under the same stressful conditions as their hosts. Here we used a comprehensive sampling of lichen-associated fungi from an alpine habitat to assess their phylogenetic relationships with fungi previously known from other niches. The multilocus phylogenetic analyses suggest that most of the 248 isolates belong to the Chaetothyriomycetes and Dothideomycetes, while a minor fraction represents Sordariomycetes and Leotiomycetes. As many lichens also were infected by phenotypically distinct lichenicolous fungi of diverse lineages, it remains difficult to assess whether the culture isolates represent these fungi or are from additional cryptic, extremotolerant fungi within the thalli. Some of these strains represent yet undescribed lineages within Chaethothyriomycetes and Dothideomycetes, whereas other strains belong to genera of fungi, that are known as lichen colonizers, plant and human pathogens, rock-inhabiting fungi, parasites and saprotrophs. The symbiotic structures of the lichen thalli appear to be a shared habitat of phylogenetically diverse stress-tolerant fungi, which potentially benefit from the lichen niche in otherwise hostile habitats.Electronic supplementary materialThe online version of this article (doi:10.1007/s13225-015-0343-8) contains supplementary material, which is available to authorized users.

Endolichenic fungi: the lesser known fungal associates of lichens

“…Although the mycobiont in most lichens is an ascomycete, a recent study shows that a basidiomycete yeast is invariably involved in this mutualism as a third partner (Spribille et al 2016). Additionally, lichens are associated with fungi lichenicolous fungi, endolichenic fungi and culturable and non-culturable non-photosynthetic bacteria (Biosca et al 2016; Muggia et al 2016). The lichens along with their associates represent a successful mode of symbiosis as they have existed for over 600 million years (Yuan et al 2005) and currently dominate nearly 10% of the Earth’s terrestrial ecosystems (Papazi et al 2015).…”

“…The species diversity of endolichenic fungi is hardly known although a pyrosequencing study showed that numerous fungi are present in lichen thalli (Bates et al 2012). A multilocus phylogenetic analysis of the fungi of alpine rock lichens revealed the presence of fungal strains of new lineages within Chaethothyriomycetes and Dothideomycetes (Muggia et al 2016). Recently, the use of molecular method has revealed the occurrence of 11 new species of lichen-forming fungi (Leavitt et al 2016).…”

“…Endolichenic fungal association could have evolved along with the lichens as has been construed for bacterial association with lichens (Grube and Berg 2009). With very few lichen species studied endolichenic fungi, it is reasonable to expect many hitherto undescribed fungal species to be present in this ecological group of fungi (Muggia et al 2016). It is also possible that the endolichenic fungi house many novel genes whose products could be exploited technologically.…”

Interface between fungi and green algae in lichen associations

“…Other non-lichenizing fungi (Harutyunyan et al 2008;Werth et al 2013;Muggia et al 2016) and bacteria (Cardinale et al 2008; were reported from cultures of lichen thalli. Some studies have suggested that the bacteria contribute to metabolic activity of the lichen symbionts (Liba et al 2006;Grube et al , 2014.…”

“…A better understanding of the role of organisms that occur on and within the lichen thallus is a direction of future study (Cernava et al 2015;Muggia et al 2016). Improved knowledge of the range and responses of these symbionts may shed light on the lichen symbiont communication process as well as the evolutionary history of the lichen association with black fungi and algal interactions.…”