Virulence of Armillaria pathogens

Department of Biochemistry, Faculty of Science, Masaryk University, Brno, CZ The genus Armillaria belongs to basidiomycetes and has been known to induce root rot disease and to cause extensive economic losses to a forest crop. The main function of this fungus in the ecological system is the decomposition of wood waste, but it can very often turn to the necrotrofic parasitism and attack a wide range of woody species. Recently, the seven species of Armillaria have been identified in Europe: A. borealis, A. cepistipes, A. ectypa, A. gallica, A. mellea, A. ostoyae and A. tabescens. These species have different pathogenic behaviour and thus the forest management necessitates confirming the presence of virulent Armillaria species in the forest. The current identification of Armillaria species have included observation of cultural characteristics, pairing tests based on both sexual and somatic incompatibility, isozyme analysis and immunological techniques. Recently, molecular-biological technique has been used to identify Armillaria species. New specific primers AR1 and AR2 were successfully used for the amplification of a specific part of internal transcribed spacer (ITS) of rDNA of Armillaria isolated from soil samples. DNA was isolated from 0.5 g of forest soil and ITS region was amplified by nested PCR reaction with external primers ITS1, ITS4 and internal primers AR1 and AR2. The presence of amplificate proved the presence of Armillaria in the soil. The individual species were distinguished by restriction fragment length polymorphisms (RFLP) analysis with restriction endonucleases HinfI. The fragments were analysed by ion-exchange HPLC. For the first time, a method is described enabling the identification of Armillaria species within one day directly from soil samples without the need for previous isolation and cultivation of mycelium of Armillaria. Cooperation projects with: Institute of forest protection and hunting, Mendel University of Agronomy and Forestry , Brno (Dr. Ing. Libor Jankovský) Moravian Museum, Brno (Dr. Vladimir Antonin) "Source":[ http://www.sci.muni.cz/~mikes/fungi.html#Laboratory%20of%20plant-pathogen%20interactions]

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