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Home • Alternaria alternata SRC1lrK2f v1.0
Scanning Electron Microscopy (SEM) image showing club-like conidia of Alternaria alternata strain SRC1lrK2f.
Scanning Electron Microscopy (SEM) image showing club-like conidia of Alternaria alternata strain SRC1lrK2f.
Image by Cara Santelli.

The genus Alternaria is a cosmopolitan group of Ascomycete fungi that are saprotrophs, plant pathogens, or occasionally human pathogens. Alternaria are critically important in ecosystem functioning where they are primary degraders of carbon, control CO2 fluxes from soils, and form both synergistic and antagonistic (pathogenic) relationships with microbes, plants, and animals.    Alternaria alternata is one of the most common species and is ubiquitous in nature.  This species has been recovered from a range of environments including soil, freshwater, seawater, plants, indoor air, and humans.  Some Alternaria alternata strains also have a demonstrated ability to produce a wide range of mycotoxins (e.g., altenuene, alternariol, and tentoxin) that play an important role in the pathogenicity of this organism.  Indeed, Alternaria alternata has been implicated as a plant pathogen in a variety of food crops, such as brown rot of tangerines, leaf spot of lemons and limes, and black rot of a variety of fruits and vegetables. In humans, this species is an opportuntistic pathogen and has been linked directly to allergenic and asthmatic reactions.  Numerous A. alternaria strains live a saprotrophic lifestyle, living off of dead and decaying organic matter.  The degradation of recalcitrant carbon compounds (including humics, lignin, cellulose) is accomplished largely by the extracellular production of enzymes and reactive small molecules such as reactive oxygen species (ROS) and oxalate. Additionally, Mn(III) compounds and Mn(III/IV) oxide minerals (highly reactive oxidants) produced by this species further promotes carbon degradation as well as the biogeochemical cycling of metals in the environment. 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 Alternaria alternata.  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.

Genome Reference(s)