Download (PDF 725 KB): https://research.fs.usda.gov/download/treesearch/56263.pdf
Abstract
Phellinus sensu lato (s.l.) is a complex of segregate genera that act as aggressive pathogens of woody plants. Nearly all of the genera in this complex have unresolved taxonomies, including
Porodaedalea, which is one of the most important trunk rot pathogens of coniferous trees throughout the northern hemisphere. In an attempt to elucidate the species within
Porodaedalea, a multilocus phylogenetic analysis was performed with partial sequences from four loci (internal transcribed spacer, nuclear large subunit,
tef1 and
rpb2) using 41 isolates that originated from North America and Europe. For reference, we analysed the neotype isolates of
Porodaedalea pini and
P. chrysoloma. Our results confirmed that
Porodaedalea pini s.s. and
P. chrysoloma s.s. are unique phylogenetic species that do not occur in North America. We detected two discrete clades of
Porodaedalea originating from the southwestern and southeastern United States. Isolates from these regions grouped with significant statistical support and represent undescribed taxa. With the exception of
P. cancriformans, our analyses revealed monophyly among 28 isolates originating from the northern United States, Canada and Fennoscandia, a group we have labelled the 'Holarctic group'. Holarctic group isolates were collected from
Larix, Picea, Pinus, Pseudotsuga and
Tsuga and were presumed to represent at least four morphological species (
P. gilbertsonii, P. laricis, P. pini s.l. and
P. piceina). Tests of gene flow and genetic differentiation detected significant differences among Holarctic group isolates by region of origin, and three subgroups were designated: (i) Atlantic-Boreal; (ii) Interior; and (iii) Pacific. Neutrality tests using the Holarctic group demonstrated significant departures from the standard neutral model of evolution and could indicate that a diversifying selection has maintained rare phenotypes in the population, which has fostered taxonomic confusion in
Porodaedalea.
Citation
Brazee, N.J.; Lindner, D.L. 2013. Unravelling the
Phellinus pini s.l. complex in North America: a multilocus phylogeny and differentiation analysis of
Porodaedalea. Forest Pathology. 43(2): 132-143. https://doi.org/10.1111/efp.12008.
