The Nuclear Protein Sge1 of Fusarium oxysporum Is Required for Parasitic Growth

Dimorphism or morphogenic conversion is exploited by several pathogenic fungi and is required for tissue invasion and/or survival in the host. We have identified a homolog of a master regulator of this morphological switch in the plant pathogenic fungus Fusarium oxysporum f. sp. lycopersici. This non-dimorphic fungus causes vascular wilt disease in tomato by penetrating the plant roots and colonizing the vascular tissue. Gene knock-out and complementation studies established that the gene for this putative regulator, SGE1 (SIX Gene Expression 1), is essential for pathogenicity. In addition, microscopic analysis using fluorescent proteins revealed that Sge1 is localized in the nucleus, is not required for root colonization and penetration, but is required for parasitic growth. Furthermore, Sge1 is required for expression of genes encoding effectors that are secreted during infection. We propose that Sge1 is required in F. oxysporum and other non-dimorphic (plant) pathogenic fungi for parasitic growth

Génération d'harmoniques dans un système double faisceau en la présence d'un champ magnétique

The h. f. oscillations generated by a symmetric system of two counter-streaming beams in the présence of a magnetic field, have been studied. They consist of a spectrum of harmonies of half the electron gyromagnetic frequency and a spectrum related to the electron transit time.Les oscillations HF engendrées dans un système symétrique de deux faisceaux opposés en présence d'un champ magnétique ont été étudiées. Le spectre se compose de raies harmoniques de la demi-fréquence gyromagnétique électronique et de raies liées au temps de transit des électrons

Méthodes alternatives de lutte contre les maladies des plantes

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The Endophytic Strain Fusarium oxysporum Fo47: A Good Candidate for Priming the Defense Responses in Tomato Roots

International audienceThe protective Fusarium oxysporum strain Fo47 is effective in controlling Fusarium wilt in tomato. Previous studies have demonstrated the role of direct antagonism and involvement of induced resistance. The aim of the present study was to investigate whether priming of plant defense responses is a mechanism by which Fo47 controls Fusarium wilt. An in vitro design enabled inoculation of the tap root with Fo47 and the pathogenic strain (FoI8) at different locations and different times. The expression levels of six genes known to be involved in tomato defense responses were quantified using reverse-transcription quantitative polymerase chain reaction (qPCR). Three genes-CHI3, GLUA, and PR-1a-were overexpressed in the root preinoculated with Fo47, and then challenged with FoI8. The genes GLUA and PR-la were upregulated in cotyledons after inoculation of Fo47. Fungal growth in the root was assessed by qPCR, using specific markers for Fo47 and FoI8. Results showed a reduction of the pathogen growth in the root of the tomato plant preinoculated with Fo47. This study demonstrated that priming of tomato defense responses is one of the mechanisms of action of Fo47, which induces a reduced colonization of the root by the pathogen

Diversity and interactions among strains of Fusarium oxysporum: application to biological control.

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Enhancing biological control by combining microorganisms

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Enhancing biological control by combining microorganisms

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