Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2019

Erindi/veggspjald / Talk/poster V55

Extended phylogeny of the lichenized algal genus Trebouxia (Trebouxiophyceae, Chlorophyta): insights from chemosystematics and symbiotic pattern of Icelandic cetrarioid lichens

Höfundar / Authors: Maonian Xu (1), Starri Heidmarsson (2), Elin S. Olafsdottir (1)

Starfsvettvangur / Affiliations: 1. Háskóli Íslands, 2. Náttúrufræðistofnun Íslands

Kynnir / Presenter: Maonian Xu

Lichen symbiont interactions (e.g., myco- and photobionts) play a crucial role in the high environmental tolerance of li- chens, in which neither symbiont can hardly survive independently. The characterization of fungal-algal association patterns is essential to understand their interactions and to elucidate the symbiotic mechanisms. Lichens are prolific producers of structurally unique secondary metabolites, which are of ecological and taxonomic importance. This study investigated fungal-algal association patterns in Icelandic cetrarioid lichens (168 specimens of 13 cetrarioid taxa) using a multi-locus phylogenetic framework, including fungal nrITS, MCM7, mtSSU, and RPB1 and algal nrITS, nrLSU, rbcL, and mtCOXII data. Lichen metabolite profiles were assessed using ultrahigh-performance liquid chromatography-mass spectrometry. Our chemical results revealed that Cetrariella delisei is the only Icelandic cetrarioid lichen producing depsides, but not aliphatic lactones, dibenzofurans, or depsidones. Most Icelandic cetrarioid lichenized fungi were found to be specifically associated to the known Trebouxia clade S (T. simplex/ suecica group), while the lichen-forming fungus C. delisei forms symbiosis with a previously unrecognized Trebouxia lineage here provisionally named as the D clade. This new Trebouxia lineage is supported by Maximum Likelihood and Bayesian phylogenetic analyses using all four included algal loci. We suggest a preliminary number of six operational taxonomic units (OTUs) in this new clade using different species delimitation methods (i.e., ABGD and bPTP). The phylogeny of the lichenized algal genus Trebouxia is re-constructed and updated. Our symbiotic association pattern results also demonstrate the importance of algal partners in shaping lichen symbiosis with the example of Icelandic C. delisei, which challenges a previous hypothesis suggesting a determining role of fungal partners.