Investigation of biological species concept in some Armillaria species in Iran

During September to November 2010-2012, 17 fruiting body specimens of Armillaria were collected from diverse forest sites in Guilan, Mazandaran and Golestan Provinces (Iran) and 24 basidiocarp derived isolates were obtained. Mating tests were performed using 10 Iranian representative isolates and 12 European tester strains of European species including A. mellea, A. gallica and A. cepistipes. Crossing tests were also used for identification of interspecific and intraspecific separation criteria. In the mating test of a total number of 360 interspecific crosses, Iranian isolates were divided into two A. mellea and A. gallica groups. Hemi-compatible and compatible reactions were found in 126 interspecific crosses. Analysis of crosses demonstrated clear separation for both MFF (mycelial fusion frequency) and BLF (black line frequency) and also change in culture morphology. Mating data clearly distinguished three species including A. mellea, A. gallica and A. cepistipes and defined sexual compatibility of Iranian species with their European counterparts. In spite of close phylogenetic relationship between Iranian A. gallica and A. cepistipes, it also represented a significant clear cut based on the sexual fertility. The results suggest that biological species concept in these fungi consist of using both somatic and sexual compatibilities that still can be used in case of selection of a proper pattern of isolates.