Monotropa uniflora: morphological and molecular assessment of mycorrhizae retrieved from sites in the sub-boreal spruce biogeoclimatic zone in central British Columbia.

Plant species in the subfamily Monotropoideae are achlorophyllous and have developed a complex mode of nutrition, receiving photosynthates from neighboring trees via shared fungi. To explore the mycorrhizal associations of Monotropa uniflora in central British Columbia (B.C.), plants were sampled from three sites: a Betula-dominated site and two sites with a mixture of conifer and hardwood trees. Fifteen M. uniflora root-clusters were sampled (five per site) and the mycorrhizal diversity was assessed using morphological and molecular (PCR-RFLP analysis and DNA sequencing) methods. Both methods showed that root-clusters (often comprising several hundred mycorrhizal tips) belonging to the same plant appeared to involve fungus monocultures in the family Russulaceae. All mycorrhizae exhibited typical Russula morphology and had mantle cystidia. Two root-clusters, one each from sites 1 and 3, lacked one of the two types of cystidia present on all other root-clusters. PCR-RFLP analysis resulted in three fragment patterns for the 15 root clusters. One molecular fragment pattern included the two root-clusters displaying the single cystidium type plus an additional root-cluster with both cystidia types. DNA sequencing of a portion of the ITS2 region of the ribosomal DNA suggests that the three variants represent different species; two of the variants clustered with the hypogeous fungi Martellia and Gymnomyces. The study provides increased evidence of low diversity and high specificity in the Monotropa-fungus relationship and suggests that M. uniflora associates uniquely with fungi in the family Russulaceae in central B.C.

Molecular phylogeny and evolutionary divergence of North American biological species of Armillaria.

Armillaria is a genus of root infecting basidiomycetes, which includes nine North American biological species. Anonymous nucleotide sequences obtained from four different primer pairs were combined to produce a data set which was analyzed phylogenetically. The data indicated that randomly chosen sequences from the genome were capable of resolving the phylogenetic history of species of Armillaria and provided strong support for intraspecies clustering. NABS III and VII formed a significant monophyletic clade, with III being derived from the more broadly distributed NABS VII. Sequences of isolates of NABS V showed a high degree of variation. This variation may be an indication of recent sympatric speciation, with NABS IX and X diverging from a genetically diverse NABS V. NABS I formed a monophyletic clade despite the variation in geographic distance among the isolates. The position of NABS II as ancestral to NABS I was discussed. However, literature evidence favored divergence of NABS II from NABS I, while this study illustrated genetic similarity of NABS II with NABS VI. NABS VI was the most divergent of the North American species and represented the outgroup. A molecular clock of NABS Armillaria was proposed.

Diagnostic difficulties caused by a nonclamped Schizophyllum commune isolate in a case of fungus ball of the lung.

The presence of clamp connections on hyphae and the development of fruiting bodies in culture are primary characters which allow identification of the basidiomycete Schizophyllum commune in cases of human infection. The diagnostic problems presented by a nonclamped, nonfruiting isolate from a dense mass in the right upper lobe of the lung in a female with a past history of pulmonary tuberculosis and diabetes are described. Several features of the isolated fungus, including rapid growth rate and white, dense, cottony colonies, tolerance to the fungicide benomyl at a concentration of 10 micrograms/ml, and susceptibility to cycloheximide at 400 micrograms/ml, suggested that it might be a basidiomycete. Transmission electron microscopy showed the presence of a dolipore septum with perforate pore cap characteristic of fungi in the class Holobasidiomycetes. However, species identification remained elusive until compatibility tests with known single-basidiospore isolates confirmed the identification of the sterile lung isolate as S. commune. Sequence analysis of the 5' internal transcribed spacer region of ribosomal DNA further supported conspecificity.

Sequence and putative secondary structure of group I introns in the nuclear-encoded ribosomal RNA genes of the fungus Hymenoscyphus ericae.

Two putative group I introns in the nuclear ribosomal RNA genes of Hymenoscyphus ericae are described. One is in the small subunit gene about 30 nucleotides upstream of the 3' end of the gene at a site common to several other group I introns. The other is in the large subunit gene approx. 930 bp downstream of the 5' end of the gene. This is the only report of an intron at this location.