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United States Department of Agriculture

Agricultural Research Service

Title: Biological Relations of Cercospora Beticola with Host Plants and Fungal Antagonists

Authors
item Lartey, Robert
item Ghoshroy, Soumitra - NEW MEXICO STATE UNIVERSI
item Caesar, Thecan
item Evans, Robert
item Lenssen, Andrew

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2006
Publication Date: July 15, 2006
Citation: Lartey, R.T., Ghoshroy, S., Caesar, T., Evans, R.G., Lenssen, A.W. 2006. Biological relations of cercospora beticola with host plants and fungal antagonists [abstract]. Joint Meeting of APS, CPS, and MSA. p. 140.

Interpretive Summary: Relations between Cercospora beticola and three host plants and potential antagonists were examined as a requisite for developing sustainable management systems. The hosts, sugar beet, safflower and the weed pitseed goosefoot developed spot lesions when manually infected with isolates C2 and Sid1of C. beticola. Scanning electron microscopic examination revealed hyphal penetration through stomatal openings. Stomatal apertures in host lesion areas and splits in sugar beet lesions revealed extensive internalized hyphae and reemergence of the pathogen after establishment of infection. Substantial hyphal mass developed eventually and covered the lesions of the host plants. In dual culture experiments, C. beticola was inhibited on agar plates by the fungal antagonists Laetisaria arvalis and three Trichoderma species, T. aureoviride, T. harzianum, and T. virens. Examination using confocal laser scanning microscopy with a two fluorescent dye staining technique showed antagonists induced death of C. beticola cells. In addition, the presence of T. virens resulted in swollen hyphal tips and disruption of their apical vesicle cluster (Spitzenkörper) of C. beticola. T. aureoviride induced release of cytoplasmic materials from burst hyphal tips, resulting to cell death. No conclusive changes were detected with T. harzianum. Additionally, L. arvalis detoxified the toxin cercosporin from C. beticola.

Technical Abstract: Relations between Cercospora beticola and three host plants and potential antagonists were examined as a requisite for developing sustainable management systems. The hosts, sugar beet, safflower and the weed pitseed goosefoot developed spot lesions when manually infected with isolates C2 and Sid1of C. beticola. Scanning electron microscopic examination revealed hyphal penetration through stomatal openings. Stomatal apertures in host lesion areas and splits in sugar beet lesions revealed extensive internalized hyphae and reemergence of the pathogen after establishment of infection. Substantial hyphal mass developed eventually and covered the lesions of the host plants. In dual culture experiments, C. beticola was inhibited on agar plates by the fungal antagonists Laetisaria arvalis and three Trichoderma species, T. aureoviride, T. harzianum, and T. virens. Examination using confocal laser scanning microscopy with a two fluorescent dye staining technique showed antagonists induced death of C. beticola cells. In addition, the presence of T. virens resulted in swollen hyphal tips and disruption of their apical vesicle cluster (Spitzenkörper) of C. beticola. T. aureoviride induced release of cytoplasmic materials from burst hyphal tips, resulting to cell death. No conclusive changes were detected with T. harzianum. Additionally, L. arvalis detoxified the toxin cercosporin from C. beticola.

Last Modified: 8/1/2014
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