On April 16 at 10:15 John Yangyuoru Kupagme will defend his doctoral thesis "Biodiversity of African soil fungi" for obtaining the degree of Doctor of Philosophy (in Botany and Mycology).
Supervisors:
Professor Leho Tedersoo, University of Tartu
Dr. Sergei Põlme, University of Tartu
Opponent:
Dr. Tesfaye Wubet, Helmholtz Center for Environmental Research - UFZ (Germany)
Summary:
Fungi are ecologically key eukaryotes that ensure nutrient cycling by breaking down organic matter and improving soil structure. Mycorrhizal relationships with plant roots enhance water and nutrient uptake, especially phosphorus, and support plant resilience to drought and other stresses. Despite their important role in agriculture, pharmaceuticals, and ecosystem functioning, fungal diversity remains poorly characterized: an estimated 2.2–3.8 million species exist, but fewer than 95% have been scientifically described, especially in tropical regions.
In my doctoral thesis, I used eDNA metabarcoding to study soil and root fungal communities across Africa. A continental survey covering 32 countries revealed clear differences between humid and dry tropical forests. The highest species richness was observed in Central and East Africa, with the lowest in North Africa. Saprotrophic fungi dominated tropical forests, ectomycorrhizal species were more common in savannas and moist forests, while arbuscular mycorrhizal fungi were more common in dry forests and the West African forest-savanna ecotones. Parasitic and pathogenic species were more abundant in savanna areas.
The structure of fungal communities was mainly shaped by mean annual temperature, rainfall and soil pH. The collaboratively created high-resolution map highlighted low-diversity desert areas and high-diversity hotspots across the savannah zones of West and East Africa and Central and Southern Africa. Studies of cocoa agroforestry in West Africa showed that climate and soil factors influenced fungal diversity more than farm age.
In addition, 93% of the ectomycorrhizal fungi associated with the tree species Alnus glutinosa were unique to Algeria, and the influence of the sampling area was stronger than that of soil factors. Overall, the work highlights the interplay among biotic, abiotic, and spatial factors, and the need to protect African soils to maintain biodiversity and ecosystem resilience amid climate and land-use change.
