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Home • Armillaria ostoyae C18/9
Photo credit: Brigitta Kiss & Laszlo Nagy
Photo credit: Brigitta Kiss & Laszlo Nagy

The genome sequence and gene models of Armillaria ostoyae C18/9 were not determined by the Joint Genome Institute (JGI), but as a collaborative led by György Sipos (now at the University of Sopron). In order to allow comparative analyses with other fungal genomes sequenced by the JGI, a copy of this genome is incorporated into Mycocosm. JGI tools were used to automatically annotate predicted proteins. Please contact László Nagy for permission to use these data in publications.


Armillaria ostoyae

The genus Armillaria comprises mushroom-forming fungi in the Agaricales. Armillaria species have an unusual biology – they include devastating pathogens, have a mutation rate three orders of magnitudes lower than that of most filamentous fungi, reach immense colony sizes and produce rhizomorphs – multicellular structures that act as underground corridors for clonal dispersal. Members of the genus show diverse lifestyles, ranging from saprotrophs to devastating tree pathogens. They cause Armillaria root rot, or shoestring rot, named after the macroscopic appearance of rhizomorphs. The disease can cause significant losses in forest areas or woody plants, including forests, parks, or vineyards, among others, mostly in the temperate zone. They produce macroscopic fruiting bodies that are edible and known as honey mushrooms. In the saprotrophic phase of their life cycle, Armillaria species cause white rot to wood.

Armillaria ostoyae, is a conifer specific pathogen widespread in the European/Eurasian temperate forests. It includes one of the largest terrestrial organisms on Earth, known as the humongous fungus, that was discovered in Malheur National Forest (Oregon). Its continuous colony covers 3.4 square miles. Recent phylogenetic analyses have revealed the existence of two allopatric species within the A. ostoyae complex. A. ostoyae is restricted to European/Eurasian forests, whereas in North America the species should be named A. solidipes. The genome of both species have been sequenced and show substantial differences, undepinning their separation. The diploid individuals of A. ostoyae, spreading very effciently by shoestring like mycelial structures, rhizomorphs, often form large colonies in the soil and have access to the roots of potential hosts in extended areas. A. ostoyae is a facultative necrotroph with isolates exhibiting a significant diversity in virulence. After the infection through root contacts, they often cause unseen root and stem rot or they may advance under the bark by invading and killing the cambium of the host.

Sequencing the genomes of Armillaria species will help understanding the biology of these species, in particular their pathogenic interactions with trees and will hopefully open the door for developing efficient strategies for containing their spread and damage to forest ecosystems.

Genome Reference(s)