Phylogeographic patterns of Armillariaostoyae in the western United States

Abstract

Nuclear ribosomal DNA regions (i.e. large subunit, internal transcribed spacer, 5.8S and intergenic spacer) were sequenced using a direct-polymerase chain reaction method from Armillaria ostoyae genets collected from the western USA. Many of the A. ostoyae genets contained heterogeneity among rDNA repeats, indicating intragenomic variation and likely intraspecific hybridization. Intragenomic variation was verified by visually editing base-sequence offsets in regions with insertions/deletions, and using sequence-specific internal primers to resequence heterogeneous regions. Phylogenetic analyses with Bayesian Inference methods were used to define groups within A. ostoyae. Analysis of A. ostoyae from outside the western USA indicated the presence of a Circumboreal group of A. ostoyae that also occurs in Utah; two other phylogeographic groups were associated with the Rocky Mountain and Pacific Northwest regions of the USA. Mixed sequence types, an indication of intraspecific hybrids, were common in some geographic regions. Hybridization events may have influenced species evolution, contributing to variation in pathogenicity and virulence. The occurrence of these groups and intraspecific hybrids also indicates that paleogeography and paleoclimate may have influenced the phylogeography of A. ostoyae. In addition, other Armillaria species were examined for evolutionary relationships with the groups of A. ostoyae. These findings will provide a basis for future research relating ecological function to genetic diversity within A. ostoyae.

Advances toward DNA-based identification and phylogeny of North American Armillaria species using elongation factor-1 alpha gene

“…Although isolate M70 has been previously identified as A. gallica by pairing tests (Morrison et al 1985) and nuclear DNA content (Kim et al 2000), AFLP data also showed this isolate as genetically distinct from the other two A. gallica isolates (ST22 and ST23) (Kim et al 2006). These data, as well as other DNA sequence data (Kim et al 2006;Hanna et al 2007), suggest that A. gallica is a diverse species that comprises multiple, genetically distinct groups which may include cryptic species (Hawksworth 2010). Confirmation of cryptic species within A. gallica will require sequence analysis of more genetic regions within multiple isolates from diverse sources.…”

“…Armillaria isolates used in this study More detailed information on the Armillaria isolates used in this study is available inKim et al 2006 NABS, North American biological species a JF313133 (ST11A), JF313134 (ST11B); for isolate ST11, the method ofHanna et al (2007) was used to decipher and edit a ''frame-shift'' caused by length variation between two gene copies, from which two separate sequences (ST11A and ST11B) were generated…”

“…Sequences were edited and aligned manually with BioEdit software (Hall 1999). For isolate ST11, the method of Hanna et al (2007) was used to decipher and edit a ''frame-shift'' because of length variation between two gene copies, from which two separate sequences (ST11A and ST11B) were generated. These edited EF-1a gene sequences of the Armillaria isolates have been deposited in GenBank (see Table 1).…”

Identification protocol for sixArmillariaspecies from northeastern North America

“…focussing on the ITS, IGS1, and LSU regions of rDNA, Hanna et al (2007) reported that heterogeneous rDNA products were common in all of these regions. rDNA heterozygosity has also been reported in diploid European A. gallica isolates (Pérez-Sierra et al 1999), A. sinapina (White et al 1998), and Armillaria nabsnona .…”

Sesquiterpene aryl ester natural products in North American Armillaria species

“…A. ostoyae represents a circumboreal parasite on conifers, while A. gemina prefers hardwood hosts and is geographically restricted to the northeastern US, Ontario, and Québec (Burdsall and Volk 1993). Although geographic subgroups of A. ostoyae have been identified (Hanna et al 2007), the low metabolic diversity was also found with our European reference strain (A. ostoyae FVA 600), whereas high metabolic diversity was typical of A. mellea. In the past, various studies utilized the structural variation of a natural product class within a fungal genus or a species to establish chemotypes of the respective organisms.…”