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Abstract: We assessed the pathogenicity of Leptographium longiclavatum sp. nov., a recently reported fungal associate of the mountain pine beetle, Dendroctonus ponderosae (Hopkins, 1902). In September 2003, 30 lodgepole pines [...]

The viability of using polymerase chain reaction (PCR) in detecting sapstain fungi in wood samples has been investigated. Ophiostoma piceae is used as the model organism because it is the most common sapstain fungi species isolated from stained lumber and logs. However, the fungi species has been divided between O. piceae for hardwoods and O. quercus for softwoods. Detecting both fungal species was achieved within four hours through a combination of microwave heating for DNA extraction and PCR with internal transcribed spacer-derived-specific primers.

Experimental studies on lodgepole pine sapwood chips, which are inoculated with four different fungal strains, indicate that fungal growth reduces up to 67% of the total resin acids level, which are primary sources of toxicity to fish. Use of wood-inhabiting fungi is an efficient and environmental friendly method for the biological degradation of resin acids in wood chips. This methodology facilitates the removal of toxicity of pulp mill effluents.

The production of monoclonal antibodies to isolated cell wall fragments of Gliocladium roseum, a potential biological control fungus of sap-staining fungi, was described. Two monoclonals, designated 6A5 and 3F12, were characterized and their specificity was assessed by ELISA, immunogold silver staining light microscopy, immunogold electron microscopy and immunoblotting. Since the antibodies also detected specific fungi in wood, they will be of value in analyzing wood colonization byG. roseum.

Abstract Background The highly aggressive pathogenic fungus Ophiostoma novo-ulmi continues to be a serious threat to the American elm (Ulmus americana) in North America. Extensive studies have been conducted in North America to understand the mechanisms of virulence of this introduced pathogen and its evolving population structure, with a view to identifying potential strategies for the control of Dutch elm disease. As part of a larger study to examine the genomes of economically important Ophiostoma spp. and the genetic basis of virulence, we have constructed an expressed sequence tag (EST) library using total RNA extracted from the yeast-like growth phase of O. novo-ulmi (isolate H327). Results A total of 4,386 readable EST sequences were annotated by determining their closest matches to known or theoretical sequences in public databases by BLASTX analysis. Searches matched 2,093 sequences to entries found in Genbank, including 1,761 matches with known proteins and 332 matches with unknown (hypothetical/predicted) proteins. Known proteins included a collection of 880 unique transcripts which were categorized to obtain a functional profile of the transcriptome and to evaluate physiological function. These assignments yielded 20 primary functional categories (FunCat), the largest including Metabolism (FunCat 01, 20.28% of total), Sub-cellular localization (70, 10.23%), Protein synthesis (12, 10.14%), Transcription (11, 8.27%), Biogenesis of cellular components (42, 8.15%), Cellular transport, facilitation and routes (20, 6.08%), Classification unresolved (98, 5.80%), Cell rescue, defence and virulence (32, 5.31%) and the unclassified category, or known sequences of unknown metabolic function (99, 7.5%). A list of specific transcripts of interest was compiled to initiate an evaluation of their impact upon strain virulence in subsequent studies. Conclusions This is the first large-scale study of the O. novo-ulmi transcriptome. The expression profile obtained from the yeast-like growth phase of this species will facilitate a multigenic approach to gene expression studies to assess their role in the determination of pathogenicity for this species. The identification and evaluation of gene targets in such studies will be a prerequisite to the development of biological control strategies for this pathogen.

Abstract Background Grosmannia clavigera is a bark beetle-vectored fungal pathogen of pines that causes wood discoloration and may kill trees by disrupting nutrient and water transport. Trees respond to attacks from beetles and associated fungi by releasing terpenoid and phenolic defense compounds. It is unclear which genes are important for G. clavigera's ability to overcome antifungal pine terpenoids and phenolics. Results We constructed seven cDNA libraries from eight G. clavigera isolates grown under various culture conditions, and Sanger sequenced the 5' and 3' ends of 25,000 cDNA clones, resulting in 44,288 high quality ESTs. The assembled dataset of unique transcripts (unigenes) consists of 6,265 contigs and 2,459 singletons that mapped to 6,467 locations on the G. clavigera reference genome, representing ~70% of the predicted G. clavigera genes. Although only 54% of the unigenes matched characterized proteins at the NCBI database, this dataset extensively covers major metabolic pathways, cellular processes, and genes necessary for response to environmental stimuli and genetic information processing. Furthermore, we identified genes expressed in spores prior to germination, and genes involved in response to treatment with lodgepole pine phloem extract (LPPE). Conclusions We provide a comprehensively annotated EST dataset for G. clavigera that represents a rich resource for gene characterization in this and other ophiostomatoid fungi. Genes expressed in response to LPPE treatment are indicative of fungal oxidative stress response. We identified two clusters of potentially functionally related genes responsive to LPPE treatment. Furthermore, we report a simple method for identifying contig misassemblies in de novo assembled EST collections caused by gene overlap on the genome.