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Home • Stagonospora sp. SRC1lsM3a v1.0
Image of Stagonospora sp. SRC1lsM3a growing in agar media and oxidizing Mn(II) compounds to produce brown-colored Mn(III/IV) oxide minerals. Inset is a scanning electron microscopy (SEM) image showing hyphae with extracellular Mn oxide minerals (arrow).
Image of Stagonospora sp. SRC1lsM3a growing in agar media and oxidizing Mn(II) compounds to produce brown-colored Mn(III/IV) oxide minerals. Inset is a scanning electron microscopy (SEM) image showing hyphae with extracellular Mn oxide minerals (arrow).
Images by Cara Santelli.

Stagonospora is a genus of filamentous Ascomycete fungi that are widely known and studied because several species are plant pathogens, although these fungi have further relevance for biocontrol and biotreatment applications as well as for the biogeochemical cycling of carbon and metals in the environment.  The best-studied species is Stagonospora nodorum (syn. Septoria nodorum or Phaeosphaeria nodorum, teleomorph), which is a major pathogen of wheat and other related cereal crops.  This fungus is responsible for major wheat crop losses worldwide.  Additionally, Stagonospora convolvuli is a pathogen of field and hedge bindweeds.  Secondary metabolites produced by different strains of S. convolvuli are being investigated as a biocontrol agent against these noxious weeds. Further, application of Stagonospora gigaspora for biotreatment of pulp mill bleachery effluents was successul in both the reduction of aromatic compounds and degradation of lignin derivatives.  Species-level determinations of Stagonospora sp. SRC1lsM3a have not yet proven successful due to inconclusive results of 18S rRNA gene and Internal Transcribed Spacer (ITS) region phylogenetic analysis, and no spores or reproductive structure are produced in culture for morphological identification. Currently, however, Stagonospora sp. SRC1lsM3a is being investigated for its role in the remediation of metal polluted environments due to the oxidation of manganese (Mn) compounds.  In addition to Mn(III) compounds and Mn(III/IV) oxide minerals (highly reactive oxidants), the extracellular production of enzymes and reactive small molecules such as reactive oxygen species (ROS) and oxalate produced by this species further promotes the degradation of recalcitrant carbon compounds (including humics, lignin, cellulose, etc.).  Production of reactive metabolites and oxidants is linked in part to secreted proteins, cell differentiation, nutrient composition, and species interactions, although the molecular mechanisms are not fully resolved. Genome sequencing in concert with transcriptome and secretome analysis of this and related Ascomycete fungal species that promote lignocellulose degradation and Mn(II) oxidation will improve our understanding of the growth-specific production and total production potential of reactive metabolites and oxidants by Stagonospora.  Ultimately, these results will improve model predictions of carbon degradation and CO2 emissions in a changing biogeochemical landscape as well as provide plausible approaches to increase carbon sequestration, metal bioremediation, and pathogen resistance. 

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