Sambýliskólfsveppir í litskófarætt – eru þeir áður óþekktir framleiðendur mikilvægra náttúruuefna? (KÓLFSVEPPA-FLÉTTUR) - verkefni lokið

Fréttatilkynning verkefnisstjóra

15.8.2022

Fjölbreytni örvera (bakteríur og sveppir) hjá íslenskum fléttum af litskófarætt (Parmeliaceae) var könnuð ásamt staðsetningu lífvirkra efna innan fléttuþalsins. Sérstaklega var leitað eftir kólfsveppum sem sambýlingum og hvort þeir mynduðu lífvirk efni í fléttusambýlinu. Greining á sveppa DNA-röðum leiddu í ljós að einungis 0,26% af heildarmagni kirnisraða tilheyrðu kólfsveppum sem flestir voru af ættkvíslinni Tremella (skjálfi). Fléttumyndandi sveppir af ættkvíslinni Vulpicida (gullinvarp og skyldar tegundir) eru marktækt tengdari kólfsveppum af ættkvíslinni Cyphobasidium en aðrar fléttumyndandi ættkvíslir. Staðsetning andlífis (antibiotic) fléttuefna, þ.e. úsnínsýru (UA) og prótolichesterinsýru (PA) var kortlögð með myndrænni massalitrófsgreiningu. Mest finnst af UA utarlega í fléttuþalinu og vegur 0,5-5 % af þurrvikt fléttunnar og er líka staðsett umhverfis sambýlisþörungana. Þrátt fyrir að PA sé einkum til staðar yst í fléttuþalinu þá er efnið greinilega myndað innan þess. Fléttur sem mynda UA og PA hafa lítið magn af Cyphobasidium sambýlingum sem bendir til að ólíklegt sé að Cyphobasidium framleiði umræddar fléttusýrur. Hluti af genamengi fléttumyndandi sveppa hefur verið sett saman byggt á kirnisröðum sem fengust með “shotgun metagenomic” raðgreiningargögnum sem gera þá kleift að bæta þróunarsögugreiningar fléttumyndandi sveppategunda.

English:

The project explored the microbial diversity of Icelandic lichens in the family Parmeliaceae and spatial distribution of bioactive metabolites in lichens. Particularly, we are interested in the presumable basidiomycetous fungal symbionts – whether they are producing the bioactive metabolites or not. Our fungal metabarcoding results showed that the basidiomycetous fungi account for less than 0.26% of total fungal reads, mostly composed of fungi of the genus Tremella. The lichen-forming fungal genus Vulpicida associates with significantly more Cyphobasidium fungi than other genera. Spatial distribution of antibiotic lichen metabolites, i.e. usnic acid (UA) and protolichesterinic acid (PA), were investigated using imaging mass spectrometry. UA is produced mostly around the outer region on lichen thalli, accounting for 0.5 to 5% lichen and it is also located around the algal symbionts. PA is however produced inside lichen thalli, and tend to be concentrated on the edges of thalli. UA- and PA-producing lichens have few Cyphobasidium fungal symbionts, and therefore they are unlikely produced by Cyphobasidium. Partial lichen-forming fungal genomes have been assembled from shotgun metagenomic sequencing data, which could be used for a more reliable estimation of fungal phylogeny.

Information on how the results will be applied

The results of imaging mass spectrometry and quantitative phytochemical analyses facilitate the selection of lichen taxa and purification of bioactive compounds. High-throughput DNA sequencing sheds light on the complexity of lichen symbiosis and improves our understanding of lichen taxonomy.

A list of the project's outputs

The project has resulted in three published papers in peer-reviewed journals, one Master's degree thesis and three manuscripts in preparation.

Published papers include:

· Xu M, Oppong-Danquah E, Wang X, Oddsson S, Abdelrahman A, Pedersen SV, Szomek M, Gylfason AE, Snorradottir BS, Christensen EA, Tasdemir D, Jameson CJ, Murad S, Andersson OS, Magnusson KP, de Boer H, Thorsteinsdottir M, Omarsdottir S, Heidmarsson S, Olafsdottir ES. 2022. Novel methods to characterise spatial distribution and enantiomeric composition of usnic acids in four Icelandic lichens. Phytochemistry 200: 113210.
DOI: 10.1016/j.phytochem.2022.113210

· Xu M, de Boer H, Olafsdottir ES, Omarsdottir S, Heidmarsson S. 2020. Phylogenetic diversity of the lichenized algal genus Trebouxia (Trebouxiophyceae, Chlorophyta): a new lineage and novel insights from fungal-algal association patterns of Icelandic cetrarioid lichens (Parmeliaceae, Ascomycota). Botanical Journal of the Linnean Society 194: 460-468.
(DOI: 10.1093/botlinnean/boaa050)

· Johannsson F, Cherek P, Xu M, Rolfsson O, Ogmundsdottir H. 2022. The Anti-Proliferative Lichen-Compound Protolichesterinic Acid Inhibits Oxidative Phosphorylation and Is Processed via the Mercapturic Pathway in Cancer Cells. In press.
(DOI: 10.1055/a-1579-6454)

Master's degree thesis is:

Gylfason AE. 2019. Content and distribution of usnic acid enantiomers in three Icelandic lichen taxa.

Three manuscripts under preparation include:

· Phylogenetic exploration of metabolite profiles and symbiotic interaction of the lichen-forming fungal genus Nephromopsis (Parmeliaceae, Ascomycota) in Iceland

· Improving the barcoding of herbarium specimens: effective mycobiont-specific PCR primers in the lichen-forming fungal family Parmeliaceae

· New microalgae associated with the lichen-forming ascomycete Cetrariella delisei in Iceland: description of the Trebouxia delisei microalga and its intrathalline diversity

Results from the project have been presented as six oral or two poster presentations in both domestic and international conferences:

Heiti verkefnis: Sambýliskólfsveppir í litskófarætt – eru þeir áður óþekktir framleiðendur
mikilvægra náttúruuefna? (KÓLFSVEPPA-FLÉTTUR) / Basidiomycete yeasts in Icelandic cetrarioid lichens: are they hidden natural product reservoirs? (BASIDIO LICHENS)
Verkefnisstjóri: Maonian Xu, Háskóla Íslands
Tegund styrks: Nýdoktorsstyrkur
Styrktímabil: 2018-2020
Fjárhæð styrks: 29,874 millj. kr. alls
Tilvísunarnúmer Rannís: 185442