On 10 December at 9:15 Petr Kohout will defend his doctoral thesis „Ecology of ericoid mycorrhizal fungi“.
Prof. Leho Tedersoo, University of Tartu, Estonia,
Prof. Urmas Kõljalg, University of Tartu, Estonia
Prof. Björn Lindahl, Swedish University of Agricultural Sciences
Vast majority of plants live in mutually beneficial partnership with soil fungi. This partnership is called mycorrhizal symbiosis, which plays a crucial role in plant nutrient uptake. Plants feed symbiotic fungi with energy-rich compounds, such as sugars. Mycorrhizal symbiosis is one of the oldest and the most widespread symbioses on the Earth. Several types of mycorrhizal symbiosis have evolved during almost 500 million years. One of the youngest mycorrhizal type is ericoid mycorrhizal (ErM) symbiosis, a mutualistic relationship formed between plants from the Ericaceae family (so-called ericoid mycorrhizal plants; e.g. blueberry, rhododendron, heather) and diverse group of soil fungi (so-called ericoid mycorrhizal fungi). Ericoid mycorrhizal plants often occur in very harsh environments on extremely poor soils, where most of the nutrients are not directly available for plants, because these are locked up in complex forms of soil organic matter. The ErM symbiosis represents a key evolutionary adaptation of ErM plants to take up the nutrients from such substrates and survive in unfavorable conditions. In spite of the importance of ErM for the plants and fungi as well as for functioning of the ecosystems, ErM remains largely overlooked compared to the more common mycorrhizal types, such as arbuscular mycorrhiza and ectomycorrhizal; and a broader general understanding of the ErM symbiosis is therefore lacking. In this thesis, I focus on Ericaceae-associated fungi from various aspects of the partnership. Firstly, this thesis aims to determine the occurrence of ericoid mycorrhizal life-style among fungi. Furthermore, the thesis also focused on determination of environmental factors which significantly affect composition of fungal communities associated with roots of ErM plants. I found a novel lineage of fungi from the Basidiomycota phylum, which formed characteristic sheathed ErM symbiosis and enhanced growth of blueberry in vitro. This mycobiont showed even better ability to degrade a highly recalcitrant substrate compare to previsouly determined ErM fungi. In addition, I found that the communities of Ericaceae root-associated fungi were affected by environmental factors such as elevation and host plant species on a local spatial scale. On the global scale I found that some ErM fungal species have a very broad distribution range, while other species have much narrower distribution range restricted to a single hemisphere or continent.