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Abstract Detail


Ecological Section

Davis, Trevor [1], Beckstead, Julie [1].

Co-Infecting Soil Fungi Interfere with a Fungal Seed Pathogen.

Cheatgrass (Bromus tectorum) is an aggressive invasive weed that excludes native grasses, disrupts the shrub-steppe ecosystem, and threatens agricultural systems. Pyrenophora semeniperda is a naturally occurring fungal seed pathogen that can cause high mortality in cheatgrass seeds and shows promise as a biocontrol. However, seeds in the seedbanks are exposed to many pathogenic and commensal fungi, and multiple infections are common. Some of these competitors—both other species and different strains of P. semeniperda—could negatively impact its ability to kill seeds as it infects, while others might have a neutral or positive effect. To address this issue and to determine how P. semeniperda will respond to other co-infecting fungi we examined trends in multiple infections via agar plate bioassays of cheatgrass. Our results indicate that commensal co-infectors significantly reduce P. semeniperda’s ability to infect and kill seeds. The rate of infection, as indicated by the appearance P. semeniperda stromata, was lowered by up to 31%, while the reduction in seed mortality ranged between 5 and 30% depending on the co-infecting species and the ratios of inoculum loads. Pathogenic co-infectors have a smaller negative impact on P. semeniperda’s virulence. Overall, we do not anticipate an appreciable reduction in its success as a biocontrol, particularly if inoculum loads are high. These results also increase our knowledge of multiple infections and raise new questions regarding the complex interactions between co-infecting fungi.


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1 - Gonzaga University, Department of Biology, 502 East Boone Avenue, Spokane, Washington, 99258, USA

Keywords:
Bromus tectorum
Pyrenophora semeniperda
Multiple infection
Seed pathogen.

Presentation Type: Poster:Posters for BSA Sections
Session: P1
Location: Event Tent/Cliff Lodge
Date: Monday, July 27th, 2009
Time: 5:30 PM
Number: P1EC007
Abstract ID:204


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