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Generation and annotation of lodgepole pine and oleoresin-induced expressed sequences from the blue-stain fungus Ophiostoma clavigerum, a Mountain Pine Beetle-associated pathogen

DiGuistini, Scott, Ralph, Steven G., Lim, Young W., Holt, Robert, Jones, Steven, Bohlmann, Jörg, Breuil, Colette
FEMS microbiology letters 2007 v.267 no.2 pp. 151-158
Ophiostoma, Pinus contorta var. latifolia, amino acid sequences, bark beetles, biosynthesis, blue-stain fungi, cDNA libraries, clones, complementary DNA, conifers, cytochrome P-450, databases, expressed sequence tags, gene expression, genes, genomics, oleoresins, pathogenesis, pathogens, sawdust, screening, transcriptome, transporters
Ophiostoma clavigerum is a destructive pathogen of lodgepole pine (Pinus contorta) forests in western North America. It is therefore a relevant system for a genomics analysis of fungi vectored by bark beetles. To begin characterizing molecular interactions between the pathogen and its conifer host, we created an expressed sequence tag (EST) collection for O. clavigerum. Lodgepole pine sawdust and oleoresin media were selected to stimulate gene expression that would be specific to this host interaction. Over 6500 cDNA clones, derived from four normalized cDNA libraries, were single-pass sequenced from the 3' end. After quality screening, we identified 5975 high-quality reads with an average [smallcapital phred] 20 of greater than 750 bp. Clustering and assembly of this high-quality EST set resulted in the identification of 2620 unique putative transcripts. [smallcapital blastx] analysis revealed that only 67% of these unique transcripts could be matched to known or predicted protein sequences in public databases. Functional classification of these sequences provided initial insights into the transcriptome of O. clavigerum. Of particular interest, our ESTs represent an extensive collection of cytochrome P450 s, ATP-binding-cassette-type transporters and genes involved in 1,8-dihydroxynaphthalene-melanin biosynthesis. These results are discussed in the context of detoxification of conifer oleoresins and fungal pathogenesis.