Doctoral defence: Daniyal Gohar “Diversity, genomics, and potential functions of fungus-inhabiting bacteria”

On 20 June at 14:15 Daniyal Gohar will defend his doctoral thesis “Diversity, genomics, and potential functions of fungus-inhabiting bacteria” for obtaining the degree of Doctor of Philosophy (in Botany and Mycology).

Supervisors:
Associate Professor Mohammad Bahram, University of Tartu; Senior Lecturer, Swedish University of Agricultural Sciences (Sweden)
Associate Professor Kadri Põldmaa, University of Tartu

Opponent:
Associate Professor/Lecturer Olga Lastovetsky, University College Dublin (Ireland)

Summary
Bacteria are ubiquitous in various habitats either as free-living organisms or as symbionts and pathogens of eukaryotic hosts. In case of mutually beneficial interactions, bacteria obtain carbon and shelter from the host while providing various benefits for the host. Research on such interactions, has contributed to improving human health as well as to enhancing plant growth, stress tolerance and resistance to pathogens. While fungi represent one of the three major kingdoms of eukaryotes performing crucial ecological functions as decomposers and symbionts, their microbiomes have been much less studied. Although fungi draw the attention of humans mainly as pathogenic microorganisms, many also produce conspicuous fruiting bodies that humans consume. Recent studies have revealed that fungal fruiting bodies harbor diverse bacterial communities that perform various functions including host growth promotion, spore dissemination, and germination. However, our understanding of these communities and their functioning remains limited. The aim of the current PhD thesis was to study the diversity and assembly mechanisms of bacterial communities during fruiting body growth, as well as the distribution patterns of fungus-inhabiting bacteria across host taxa and geographical regions. In addition, genomic features important for bacterial adaptation to fungal habitats were analyzed. The results indicate that bacteria potentially promoting fruiting body growth remain abundant throughout the growth cycle but are replaced by pathogenic and saprotrophic bacteria in mature fruiting bodies. It was also found that the diversity and composition of bacterial communities varies depending on the phylogenetic relationships of host fungi, while climate and soil properties are not significant in this respect. Furthermore, results presented in this thesis point to the complementary role of bacteria for the functioning of the fungal holobiont, as has been shown for plants and animals. By elucidating the functions and community structure of fungus-inhabiting bacteria, this thesis offers novel insights into the intricate dynamics and distribution patterns of bacterial-fungal interactions across diverse ecosystems.