Canadian Forest Service Publications
Structural changes of spores of tree fungal pathogens after treatment with the designed antimicrobial peptide D2A21. 2000. Rioux, D.; Jacobi, V.; Simard, M.; Hamelin, R.C. Canadian Journal of Botany 78(4): 462-471.
Issued by: Laurentian Forestry Centre
Catalog ID: 20497
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In vitro effects of the antimicrobial synthetic D2A21 peptide on the structure of spores of four fungal pathogens causing important tree diseases were examined by microscopy in parallel with tests to measure inhibition of spore germination. With light microscopy, the use of SYTOX® green stain indicated that the peptide rapidly altered the plasma membrane of conidia of three Ascomycetes: Gremmeniella abietina (Lagerberg) Morelet var. abietina Petrini et al., Ophiostoma ulmi (Buism.) Nannf., and Nectria galligena Bres. With basidiospores of Cronartium ribicola J.C. Fisch., a difference between control and treated spores was also found, but it was less pronounced than with conidia of the Ascomycetes. In transmission electron microscopy, untreated conidia showed typical cytoplasmic contents with the regular presence of mitochondira, ribosomes, and nuclei, at times accompanied by vacuoles of various sizes. At concentrations of the peptide inhibitory to spore germination, plasma membranes, as well as nuclear and mitochondrial envelopes, were either generally difficult to discern or were distorted and swollen. At more advanced stages, the cytoplasm of treated spores contained numerous vesicles and was iin places more electron-dense than in controls. Cytoplasm leakage was also regularly observed. Present observations strongly suggest that the primary site of action of this peptide is located at the plasma membrane level.