Canadian Journal of Botany - Revue Canadienne de Botanique (2000) 78, 462-471
D. Rioux, V. Jacobi, M. Simard and R.C. Hamelin (2000)
Structural changes of spores of tree fungal pathogens after treatment with the designed antimicrobial peptide D2A21
Canadian Journal of Botany - Revue Canadienne de Botanique 78 (4), 462-471
Abstract: 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 mitochondria, 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 in 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.
Les effets in vitro du peptide antimicrobien synthétique D2A21, sur la structure de spores de quatre champignons pathogènes responsables de maladies importantes des arbres, ont été examinés en microscopie conjointement avec des tests de germination. En microscopie photonique, l'emploi du réactif SYTOX® green a révélé que le peptide altère rapidement le plasmalemme des conidies des trois Ascomycètes : Gremmeniella abietina (Lagerberg) Morelet var. abietina Petrini et al., Ophiostoma ulmi (Buism.) Nannf., et Nectria galligena Bres. Une différence entre les basid-iospores traitées et témoins des Cronartium ribicola J.C. Fisch. a aussi été notée bien que celle-ci ait été moins prononcée que chez les conidies des Ascomycètes. En microscopie électronique à transmission, les conidies témoins avaient un cytoplasme typique avec la présence régulière de mitochondries, de ribosomes et de noyaux, accompagnée parfois de vacuoles de différentes tailles. Aux concentrations du peptide inhibant la germination des spores, le plasmalemme ainsi que les enveloppes nucléaire et mitochondriale étaient soit difficiles à discerner, soit gonflées et difformes. À un stade plus avancé, le cytoplasme des spores traitées montrait plusieurs vésicules ainsi que des parties de cytoplasme plus opaques aux électrons. Des fuites de cytoplasme étaient également observées. Les observations de cette étude suggèrent fortement que le site d'action primaire de ce peptide se situe dans le plasmalemme.
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Link to article at publishers website
Database assignments for author(s): Richard C. Hamelin
Research topic(s) for pests/diseases/weeds:
control - general
Pest and/or beneficial records:
| Beneficial | Pest/Disease/Weed | Crop/Product | Country | Quarant.
|
|---|---|---|---|---|
| Neonectria ditissima | ||||
| Cronartium ribicola | ||||
| Ophiostoma ulmi | ||||
| Gremmeniella abietina |
