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Ultrastructural studies of the mode of penetration byPhoma macdonaldiiin sunflower seedlings

Roustaee, Ali Mohammad and Dechamp-Guillaume, Grégory and Gelie, Brigitte and Savy, C. and Dargent, Robert and Barrault, Gérard Ultrastructural studies of the mode of penetration byPhoma macdonaldiiin sunflower seedlings. (2000) Phytopathology, 90 (8). 915-920. ISSN 0031-949X

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Official URL: https://doi.org/10.1094/PHYTO.2000.90.8.915

Abstract

An ultrastructural investigation of the artificial inoculation of sunflower with Phoma macdonaldii conidia was undertaken using light, scanning, and transmission electron microscopy to elucidate the host-parasite relationship. The behavior of the conidia deposited on the cotyledon petiole was investigated at various time intervals after inoculation. Conidia adhesion and germination were observed first. The cotyledon petiole was invaded by the fungus directly through the cuticle and via stomata. Externally, the spore and germ tube were covered with a mucilaginous polysaccharide sheath of a cotton-like appearance and of variable thickness. At the time of penetration, the host cuticle was perforated mechanically. The cuticle was slightly depressed and no enzymatic alteration could be observed. The fungus did not form appressoria on the surface of the host tissues but developed an infection peg. As soon as the cuticle barrier was crossed, the fungus rapidly colonized the host parietal layer. In a first step, the plasmalemma of the host cell appeared to be stuck against the cell wall. As soon as the fungus passed through the epidermal cell wall to reach the host cytoplasm, the plasmalemma was disrupted, and the subsequent rapid breakdown of cell integrity favored the colonization of the tissues by the pathogen.

Item Type:Article
Additional Information:Thanks to The American Phytopathological Society (APS). This is an open access article available at : https://apsjournals.apsnet.org/doi/10.1094/PHYTO.2000.90.8.915
HAL Id:hal-02878787
Audience (journal):International peer-reviewed journal
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Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
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Deposited On:15 Jun 2020 09:52

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