Root rot of pea: characterization and biocontrol of the soil-borne disease complex including Aphanomyces euteiches

Pea root rot is an increasing constraint in most of intensive pea cropping areas across the globe. The pathogenic complex responsible for the disease is composed of soil-borne fungal and oomycete pathogens such as Fusarium solani, F.oxysporum, F. avenaceum, F. culmorum, Rhizoctonia solani, Thielaviopsis basicola, Ascochyta pinodella, Pythium spp., Aphanomyces euteiches and probably others not yet identified. The diversity of their ecological and pathogenic properties can explain the worldwide dispersion of the disease and the absence of chemical, agricultural or genetic control tools. My research program aims at characterizing the parasitic consortium occurring in the North of France and at…

Mechanisms involved in spatial and temporal mobility of disease patches caused by Rhizoctonia solani in sugar beet field : Induction of antagonists within disease patch

National audience; Rhizoctonia solani AG 2-2 causes damping-off and root rot on sugar beet in patches that are highly mobile both on spatial and temporal scales. They never occur in the same place where they were in the previous season. The aim of the present study was to uncover the mechanisms underlying the dynamics of disease patches. It was observed that soil inoculum potential was higher within diseased patch than in healthy area. However, the dormant pathogen in healthy area was stimulated by addition of buckwheat meal more than that in diseased patch. In addition soil from diseased area was more suppressive towards the disease. We did not observe significant differences in bacterial …

Ecological role of mycotoxin and consequences of the presence of mycotoxins in crop residues on the survival and pathogenic activity of Fusarium graminearum

Recovery of mutants impaired in pathogenicity after transposition of Impala in Fusarium oxysporum f.sp. melonis

The ability of transposon impala to inactivate genes involved in pathogenicity was tested in Fusarium oxysporum f. sp. melonis. Somatic excision of an impala copy inserted in the nitrate reductase-encoding niaD gene was positively selected through a phenotypic assay based on the restoration of nitrate reductase activity. Independent excision events were analyzed molecularly and shown to carry reinsertedimpala in more than 70% of the cases. Mapping of reinserted impala elements on large NotI-restriction fragments showed that impala transposes randomly. By screening 746 revertants on plants, a high proportion (3.5%) of mutants impaired in their pathogenic potential was recovered. According t…

Identification of potential mycoherbicides using a metabarcoding approach

National audience

Characterization of Fusarium oxysporum populations by growth parameter evaluation in microtiter plates

Trophic competition for the C source is the main mechanism involved in the interaction between pathogenic and non-pathogenic populations of Fusarium oxysporum. Therefore, a phenotypical characterization based on the growth characteristics of these populations will provide classical genotypical characterizations with additionnal information of ecological significance.

Identification of the pathogens responsible for the surface deteriorations on the potato tubers

Nouveaux concepts de gestion des bioagresseurs du sol par approche conservatoire de leur biodiversité

Genetic Diversity of Pathogenic and Nonpathogenic Populations of Fusarium oxysporum Isolated from Carnation Fields in Argentina.

In order to elucidate the origin of Fusarium oxysporum f. sp. dianthi in Argentina, the genetic diversity among pathogenic isolates together with co-occurring nonpathogenic isolates on carnation was investigated. In all, 151 isolates of F. oxysporum were obtained from soils and carnation plants from several horticultural farms in Argentina. The isolates were characterized using vegetative compatibility group (VCG), intergenic spacer (IGS) typing, and pathogenicity tests on carnation. Seven reference strains of F. oxysporum f. sp. dianthi also were analyzed and assigned to six different IGS types and six VCGs. Twenty-two Argentinean isolates were pathogenic on carnation, had the same IGS typ…

Hydro-contamination fongique par Fusarium spp. en milieu hospitalier pendant une période de construction

Détermination des causes de l'apparition des altérations superficielles du tubercule de pomme de terre

Cause and duration of mustard incorporation effects on soil-borne plant pathogenic fungi

International audience; Two fungal plant pathogens, Rhizoctonia solani AG 2-2 and Fusarium oxysporum f.sp. lini, were studied in relation to general responses of soil fungi and bacteria following incorporation of Brassica juncea. Our aim was to understand to what extent the changes in the biological and physicochemical characteristics of the soil could explain the effects on the studied pathogens and diseases, and to determine the temporal nature of the responses. Short-term effects of mustard incorporation (up to 4 months) were investigated in a microcosm experiment, and compared with a treatment where composted plant material was incorporated. In a field experiment, the responses were fol…

Épidémiologie de populations de Fusarium oxysporum et F. dimerum en milieu hospitaliers à Dijon et Nancy

Fusarium oxysporum et F. dimerum sont des champignons d'origine tellurique présents dans de nombreux écosystèmes terrestres mais ils ont été récemment détectés dans les systèmes de distribution d'eau de bâtiments hospitaliers1. Une enquête épidémiologique incluant divers bâtiments hospitaliers sur différents sites, des complexes non-hospitaliers et des maisons individuelles a été menée pendant deux ans dans deux villes françaises, Dijon et Nancy. Les champignons ont été détectés seulement dans les canalisations de bâtiments hospitaliers et n'ont pas été détectés dans celles des autres immeubles ni dans l'eau du réseau urbain. Cette distribution surprenante s'explique par une combinaison de …

Defense Responses of Fusarium oxysporum to 2,4-Diacetylphloroglucinol, a Broad-Spectrum Antibiotic Produced by Pseudomonas fluorescens

A collection of 76 plant-pathogenic and 41 saprophytic Fusarium oxysporum strains was screened for sensitivity to 2,4-diacetylphloroglucinol (2,4-DAPG), a broad-spectrum antibiotic produced by multiple strains of antagonistic Pseudomonas fluorescens. Approximately 17% of the F. oxysporum strains were relatively tolerant to high 2,4-DAPG concentrations. Tolerance to 2,4-DAPG did not correlate with the geographic origin of the strains, formae speciales, intergenic spacer (IGS) group, or fusaric acid production levels. Biochemical analysis showed that 18 of 20 tolerant F. oxysporum strains were capable of metabolizing 2,4-DAPG. For two tolerant strains, analysis by mass spectrometry indicated…

Adaptation inattendue de populations de Fusarium oxysporum et F. Dimerum au milieu aquatique urbain des conduites d'eau de bâtiments hospitaliers à Dijon et Nancyξ

National audience; Fusarium oxysporum et F. dimerum sont des champignons d'origine tellurique présents dans de nombreux écosystèmes terrestres mais ils ont été récemment détectés dans les systèmes de distribution d'eau de bâtiments hospitaliers. Une enquête épidémiologique incluant divers bâtiments hospitaliers sur différents sites, des complexes non-hospitaliers et des maisons individuelles a été menée pendant 2 ans dans deux villes françaises Dijon et Nancy. Les champignons ont été détectés seulement dans les canalisations de bâtiments hospitaliers et n'ont pas été détectés dans celles des autres immeubles ni dans l'eau du réseau urbain. Cette distribution surprenante s'explique par une c…

Ecological fitness of the biocontrol agent Fusarium oxysporum Fo47 in soil and its impact on the soil microbial communities

Some nonpathogenic strains of Fusarium oxysporum can control Fusarium diseases responsible for severe damages in many crops. Success of biological control provided by protective strains requires their establishment in the soil. The strain Fo47 has proved its efficacy under experimental conditions, but its ecological fitness has not been carefully studied. In a series of microcosm studies, the ability of a benomyl-resistant mutant Fo47b10 to establish in two different soils was demonstrated. One year after its introduction at two concentrations in the disinfected soils, the biocontrol agent (BCA) established at similar high population densities, whereas in the nondisinfected soils it survive…

Genetic diversity of Rhizoctonia solani associated with potato tubers in France.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; The soilborne fungus Rhizoctonia solani is a pathogen of many plants and causes severe damage in crops around the world. Strains of R. solani from the anastomosis group (AG) 3 attack potatoes, leading to great yield losses and to the downgrading of production. The study of the genetic diversity of the strains of R. solani in France allows the structure of the populations to be determined and adapted control strategies against this pathogen to be established. …

Involvement of various anastomosis groups of Rhizoctonia solani in the superficial blemishes on potato tubers

Ecological role of mycotoxins in wheat crop residues and consequences on the multitrophic interactions in the soil and further development of Fusarium graminearum

Format du poster : 21 X 29,7; absent

Time dependent response of Rhizoctonia solani to mustard incorporation

SPE;EA communication orale, résumé; International audience

Identification des agents pathogènes du sol associés aux altérations superficielles du tubercule de pomme de terre

Identification des agents pathogènes du sol associés responsables des altérations superficielles du tubercule de pomme de terre

Pathogenic variability and genetic characterization of Rhizoctonia solani AG-2-2 causing crown and root rot on sugar beet in France

Genetic diversity of Fusarium oxysporum and related species pathogenic on tomato in Algeria and other Mediterranean countries

In order to characterize the pathogen(s) responsible for the outbreak of fusarium diseases in Algeria, 48 Fusarium spp. isolates were collected from diseased tomato in Algeria and compared with 58 isolates of Fusarium oxysporum originating from seven other Mediterranean countries and 24 reference strains. Partial sequences of the translation elongation factor EF-1α gene enabled identification of 27 isolates as F. oxysporum, 18 as F. commune and three as F. redolens among the Algerian isolates. Pathogenicity tests confirmed that all isolates were pathogenic on tomato, with disease incidence greater at 28°C than at 24°C. All isolates were characterized using intergenic spacer (IGS) DNA typing…

Root rot of pea : characterization and biocontrol of the soil-borne disease complex including Aphanomyces euteiches

Pea root rot is an increasing constraint in most of intensive pea cropping areas across the globe. The pathogenic complex responsible for the disease is composed of soil-borne fungal and oomycete pathogens such as Fusarium solani, F.oxysporum, F. avenaceum, F. culmorum, Rhizoctonia solani, Thielaviopsis basicola, Ascochyta pinodella, Pythium spp., Aphanomyces euteiches and probably others not yet identified. The diversity of their ecological and pathogenic properties can explain the worldwide dispersion of the disease and the absence of chemical, agricultural or genetic control tools. My research program aims at characterizing the parasitic consortium occurring in the North of France and at…

Production and characterization of pathogenicy-deficient mutants of Fusarium oxysporum f. sp. melonis

Impact d'amendements organiques sur la structure des communautés microbienne des sols : Choix des méthodes, validation et résultats

Molecular tools to monitor a biocontrol agent and to assess its environmental impacts

The use of non pathogenic strains of Fusarium oxysporum has been proposed to control Fusarium diseases responsible for severe damages in many crops of economical importance. In order to monitor the biocontrol strain Fo47 after application in greenhouse and field, we have developed a specific molecular tool based on a sequence characterized amplified region (SCAR). Primers targeting a 210-bp fragment were designed to set up a real time PCR assay allowing the identification of the biocontrol strain and its quantification in environmental samples. The assay enabled specific detection of the strain in soils without cross detection of autochthonous populations of F. oxysporum. After its introduc…

Diversité des populations pathogènes de Fusarium oxysporum associés à la tomate en Algérie et sur le pourtour Méditerranéen

La santé des plantes passe par la santé des sols

Diversité génétique au sein de la forme spéciale cyclaminis de Fusarium oxysporum et recherche d’un marqueur spécifique

Le cyclamen est la 3e plante fleurie la plus vendue en France. Une des maladies dommageables de cette culture est la fusariose, causée par Fusarium oxysporum f. sp. cyclaminis (FoCy). Cette forme spéciale, inféodée au cyclamen n’est pas différenciable des autres formes spéciales et souches saprophytes. En se développant dans le xylème, FoCy entraîne la mort de la plante. Quand les symptômes externes apparaissent, la plante est condamnée. La lutte chimique est inefficace, la lutte variétale est inexistante, et les mesures prophylactiques sont difficilement applicables. Pour détecter le pathogène précocement et améliorer la lutte, nous nous sommes intéressés à sa diversité génétique. Pour cel…

Verticillium chez l'aubergine à travers le projet Vasculeg. Bioagresseurs présents et caractérisation (1ère partie)

Vascular wilt diseases of vegetable crops remain a major problem for eggplant growers in particular. After having used genetic resistance to Verticillium for several years, they are again confronted with the same problems. The VASCUleg project has led to a precise evaluation of the current situation on farms. Apart from the fungus that causes vascular disease, other pathogens are also present creating a whole range of bioagressors in different zones of production. The characterisation of isolated strains is quite complicated due to the complexity of Verticllium: new classification of Verticillium species, difficult identification of races and low aggressiveness of strains. V. dahliae is onl…

Orobanche rameuse du tabac (Phelipanche ramosa L.) : Identifier de nouvelles solutions conventionnelles et de biocontrôle

The branching broomrape, Phelipanche ramosa L. is an obligate parasitic plant, which in a few years became a major agronomic problem for tobacco crops in France. Two approaches, aiming at controlling broomrape were tested within the framework of the ELIOT project grouping Arvalis, the CT2F cooperative and the INRA center of Dijon. The first relates to sulfonylurea herbicides, including rimsulfuron and sulfosulfuron and a systemic herbicide of the cyclohexanediones family, clethodim. The results, although instructive, do not reflect an effective control of broomrape. The second approach deals with the search for soil-borne fungi that are pathogenic to broomrape. A large number of fungal stra…

A Clonal Lineage of Fusarium oxysporum Circulates in the Tap Water of Different French Hospitals.

ABSTRACT Fusarium oxysporum is typically a soilborne fungus but can also be found in aquatic environments. In hospitals, water distribution systems may be reservoirs for the fungi responsible for nosocomial infections. F. oxysporum was previously detected in the water distribution systems of five French hospitals. Sixty-eight isolates from water representative of all hospital units that were previously sampled and characterized by translation elongation factor 1α sequence typing were subjected to microsatellite analysis and full-length ribosomal intergenic spacer (IGS) sequence typing. All but three isolates shared common microsatellite loci and a common two-locus sequence type (ST). This S…

Can Rhizoctonia solani disease be naturally controlled in a sugar beet field ?

International audience

Impact of deoxynivalenol on soil microflora and fauna

F. graminearum is an important pathogen that causes head blight of cereal crops as wheat and maize. It also produces the mycotoxins (as Deoxynivalenol=DON) which are toxic to the human and animals. During the off season the pathogen survives in the soil, on weeds and in crop residues. A 24 weeks study was conducted in controlled conditions (microcosms of natural soil, 17 °C, 80% WHC) to test whether the presence of DON in the wheat crop residues gives competitive advantage to F. graminearum over the other soil microflora and fauna to survive and develop a primary inoculum during the decomposition process. This study was carried out in the presence of the whole soil biota (i.e. fungi, bacter…

Évaluation de bioindicateurs d'impact du recyclage de produits résiduaires organiques en sols cultivés: lien avec les modifications des caractéristiques physico-chimiques du sol

Communication orale, résumé étendu; absent