Characterisation of the genes behind the interaction of Armillaria ostoyae with its hosts

Species of the basidiomycete genus Armillaria are significant components of the mycoflora of numerous forest ecosystems worldwide. As saprotrophic white rot fungi they are efficient decomposer of dead wood and as aggressive pathogens they cause root and butt rot on a wide variety of woody plants. Among the European Armillaria species Armillaria ostoyae is known as an aggressive parasite on conifers.

In infected forest stands Armillaria spreads in the soil by the formation of rhizomorphs, root-like fungal structures, or by mycelium growing from infected to uninfected roots. After penetration of the roots, Armillaria invades the cambium of its host with specialised fungal structures, so called mycelial fans, eventually killing the host.

The aim of the project is to reveal the genetic basis behind the parasitic interaction of A. ostoyae with Norway spruce. Potential candidate genes for virulence will be identified based on the genome sequence of A. ostoyae and gene expression patterns observed during saprotrophic and parasitic growth of Armillaria on Norway spruce seedlings, and then studied in several Armillaria strains showing different degrees of virulence towards Norway spruce. 

Knowing the genes making A.ostoyae an aggressive parasite on conifers will improve the understanding of necrotrophic tree-pathogen interactions and could eventually lead to the development of new control strategies for Armillaria root disease in forest stands and fruit tree plantations.