Molecular identification of wood-decaying fungi of <i>Armillaria</i> genus widespread in Eastern Siberia and the Far East of Russia using ITS, IGS-1-1 and <i>Tef-1α</i> genetic markers

The genus Armillaria is an essential component of forest ecosystems playing very important ecological role in dead wood decomposition, but it often becomes a serious pathogen causing white root rot in trees. It is also known that Armillaria species significantly differ in the level of pathogenicity. Thus, accurate identification of Armillaria is critical for assessing the risk of tree disease. In this study we analyzed 28 Armillaria isolates from Siberia and the Far East using nucleotide sequences of ITS, IGS-1-1 and TEF-1α gene regions and generated phylogenetic trees based on maximum likelihood method. In total, four Armillaria species were identified: A borealis, A. cepistipes, A. ostoyae and A. gallica. A. borealis was the most frequent among collected isolates (18 out of 28 isolates). A. gallica, A. cepistipes and A. ostoyae were much less frequent with two, five and three isolates out of 28, respectively. Thedistribution of Armillaria species in Siberia and the Far East was described for the first time. It is concluded that further studies are necessary to determine the role of Armillaria in trees pathological dieback, and A. borealis should be a key focus.