Inferences on the phylogeography of the fungal pathogen Heterobasidion annosum, including evidence of interspecific horizontal genetic transfer and of human-mediated, long-range dispersal

Multiple cryptic species with divergent substrate affinities in the Serpula himantioides species complex

“…The lack of a distinct phylogeographical structure within PS5 presumably indicates recent long-distance dispersal events. It is well-known that many basidiomycetes have been spread by man on infected timber or plants (Coetzee et al 2001;Gonthier et al 2004;Linzer et al 2008;Pringle et al 2009) and this could also be the case with S. himantioides. Within PS5, a high level of genetic variation is found among the isolates from East Asia and North America.…”

Impacts of exotic forest pathogens on Mediterranean ecosystems: four case studies

“…crates or latrines brought by the American troops). As a result, two phylogenetically distinct fungi, which evolved separately in North America and in Eurasia, are now in contact (Linzer et al 2008;Otrosina and Garbelotto 2010). This sudden co-occurrence is leading to genetic exchanges between the two taxa, although the European H. annosum is only sporadically present in the habitat colonized by the more assertive American species (Gonthier and Garbelotto 2011).…”

Comparing the influences of ecological and evolutionary factors on the successful invasion of a fungal forest pathogen

“…Using the same methodology described above, a total of 27 fungal isolates, including 8 North American, 10 Eurasian and 9 invasive North American genotypes (Table 1) were each inoculated on 6 cuttings of this single tree. All genotypes of North American provenance were isolated from the most likely source population for the Italian invasion (Linzer et al 2008). Six cuttings were mock-inoculated as previously described.…”

“…The North American H. annosum P intersterility group (ISG) was introduced in coastal forests of Italy presumably during World War II, where its sister taxon, H. annosum sensu stricto (s.s.), is present (Gonthier et al 2004. Phylogenetic analysis has shown that the North American H. annosum P ISG and Eurasian H. annosum s.s. operational taxonomic units (OTUs) are sister taxa in a monophyletic clade and that the invasive genotypes likely originated in eastern North America (Linzer et al 2008). Heterobasidion annosum P ISG has subsequently become invasive in Italy: both trappings of airborne meiospores and sampling fungal fruitbodies have shown the invasive pathogen is abundant along approximately 100 km in the Latium region around Rome, while the presence of the native Heterobasidion on the coast is limited (D'Amico et al 2007;Gonthier et al 2007).…”