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Home • Grosmannia clavigera kw1407
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Life cycle and infection process of MPB and associated microorganisms. (A) MPBs disperse during early summer; both sexes of MPB carry blue stain fungi. (B) Representative phenotypes of Gc. Light micrographs of a-sexual stage characterized with mononematous (i) and synnematous (ii) conidiophores reproducing conidia. (iii) Light micrograph of sexual structure characterized by a spherical ascocarp oozing ascospores. (iv) Stereomicrograph of conidiophores that grow inside the MPB gallery and ascocarps (Inset) on the inner bark of lodgepole pine. Photo credit: Scott DiGuistini et al.

The genome sequence and gene predictions of Grosmannia clavigera were not determined by the JGI, but were downloaded from NCBI and have been published, transcriptome analyses (2011), de novo genome sequence assembly (2009). Please note that this copy of the genome is not maintained by the author and is therefore not automatically updated.

Bark beetles and their fungal associates have inhabited conifer hosts since the Mesozoic era, and are the most economically and ecologically significant forest pests in the northern hemisphere. The current outbreak of the mountain pine beetle (MPB, Dendroctonus ponderosae) in western North America is the largest since the early 1900s.

Among the MPB-associated microbiota, the ascomycete Grosmannia clavigera is a critical component of this large-scale epidemic. This pathogenic fungus can kill lodgepole pine without the beetle when inoculated at a high density; however, the mechanisms by which the fungus kills trees are not fully characterized. The association between bark beetles and vectored fungi is symbiotic. The fungi benefit because beetles carry them through the tree bark into a new host's nutrient-rich tissues. When G. clavigera is manually inoculated below the bark of seedlings or mature trees, as a single fungal inoculum point, it induces the formation of a phloem lesion (i.e., a dark necrotic zone of tissue) that contains high concentrations of tree oleoresins and phenolics, suggesting that the host prevents further fungal colonization. At higher inoculation densities, with inocula in multiple locations, the fungus will also invade the sapwood adjacent to the lesions and block water transport to the crown of the tree.

 

Genome Reference(s)