Abstract
This review considers current knowledge surrounding species boundaries of the Armillaria root-rot pathogens and their distribution. In addition, a phylogenetic tree using translation elongation factor subunit 1-alpha (tef-1α) from isolates across the globe are used to present a global phylogenetic framework for the genus. Defining species boundaries based on DNA sequence-inferred phylogenies has been a central focus of contemporary mycology. The results of such studies have in many cases resolved the biogeographic history of species, mechanisms involved in dispersal, the taxonomy of species and how certain phenotypic characteristics have evolved throughout lineage diversification. Such advances have also occurred in the case of Armillaria spp. that include important causal agents of tree root rots. This commenced with the first phylogeny for Armillaria that was based on IGS-1 (intergenic spacer region one) DNA sequence data, published in 1992. Since then phylogenies were produced using alternative loci, either as single gene phylogenies or based on concatenated data. Collectively these phylogenies revealed species clusters in Armillaria linked to their geographic distributions and importantly species complexes that warrant further research.
Highlights
Armillaria spp. (Basidiomycota, Agaricales, Physalacriaceae) are amongst the best known and most important pathogens of forest trees but are beneficial to horticulture and growth of edible fungi
Phylogenetic studies based on ITS, intergenic spacer 1 region (IGS-1) or a combination of these regions together with tef -1α sequences have shown that isolates of A. sinapina and A. cepistipes are closely related to Armillaria species in the A. gallica lineage [25,63,64]
Phylogenetic studies based on ITS, IGS-1 and tef -1α sequence data have revealed geographic clades within the lineage, distinguished by their origins
Summary
Armillaria spp. (Basidiomycota, Agaricales, Physalacriaceae) are amongst the best known and most important pathogens of forest trees but are beneficial to horticulture and growth of edible fungi. Matheny et al [35] showed that rpb sequences can be used to resolve the phylogeny between closely related species in the Basidiomycota This led to the research of Brazee et al [39] to evaluate partial tef -1α, rpb, and nLSU sequences for the identification of isolates representing A. calvescens and A. gallica from north-eastern North America and the application of this gene in a phylogeny of six Armillaria species from that geographic region. Showed that sequences from the rpb gene cannot discriminate between A. calvescens and A. gallica They found that these species and the four other species included in their study (A. gemina, A. mellea, A. sinapina, and A. solidipes) could be separated based on tef -1α gene sequences. Guo et al [6] utilised β–tubulin, in addition to ITS and tef -1α, sequence to study the phylogenetic relationships of Chinese biological species of Armillaria. This method, has not been employed in subsequent phylogenetic studies of Armillaria
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
