Genomic insights into the reproductive biology of Icmadophilaceae species (lichenized ascomycetes)
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Sexual reproduction or its absence has significant consequences for the evolutionary potential of a species, but little is known of the molecular basis of mating systems in non-model organisms. In Fungi, an extremely diverse and ecologically important group of Eukaryotes, sexual identity is regulated by mating type (MAT) genes with specific protein domains. The MAT genes determine if a species is capable of selfing (homothallism) or not (heterothallism). Among Fungi, almost one fifth of the species establish symbiotic associations with algae or cyanobacteria, that is, they form lichens. Yet, very few studies have explored the reproductive genetics of lichenized species. In this work, I extended current research to a poorly known family of lichen-forming fungi: the Icmadophilaceae. I used Next Generation Sequencing (NGS) genomic and transcriptomic data to produce gene models of the MAT genes and its flanking regions of four representative species. I found that the putative asexual Thamnolia vermicularis and Siphula ceratites, as well as the sexual Dibaeis baeomyces have a gene configuration concordant with heterothallism, while the sexual Icmadophila ericetorum is most likely homothallic. Additionally, I applied a number of methods to detect recombination as a proxy for cryptic sex in T. vermiculars populations from the Northern Hemisphere. Like previous studies, I found no evidence of recombination and very little genetic variation, which is at odds with the recovered structure of the MAT locus. On the other hand, a preliminary exploration of the GC content of the metagenome (including all the genomes within the lichen thallus) of S. ceratites revealed that the symbiotic association involves Alphaproteobacteria, as has been described before for taxonomically unrelated lichens but never before for this species. Overall, my results offer a wealth of information for new and more advance research into the reproductive and evolutionary biology of Icmadophilaceae species, an unexplored portion of fungal biodiversity.
Place, publisher, year, edition, pages
2014. , 51 p.
Fungi, Mating type genes, Lichens, Icmadophilaceae, Genomics, Transcriptomics, Gene annotation, bioinformatics
IdentifiersURN: urn:nbn:se:uu:diva-233523OAI: oai:DiVA.org:uu-233523DiVA: diva2:753426
Master Programme in Biology
Johannesson, Hanna, Professor
Brunberg, Anna-Kristina, Associate Professor