Inhibition de champignons phytopathogènes par des bactéries isolées du sol et de la rhizosphère de légumineuses (original) (raw)
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2017
L'objectif de cette these est d'evaluer les modifications du metabolisme secondaire des plantes contaminees aux elements trace metalliques (ETM) et leurs consequences sur les communautes bacteriennes rhizospheriques associees incluant des bacteries presentant des phenotypes de MultiDrug Resistance (MDR). Nous nous sommes focalises sur deux contextes de sols exposes aux metaux : la phytoremediation de sites miniers au Vietnam et la reconversion de sols agricoles contamines par la re-deposition atmospherique d'activites metallurgiques en France. Nos resultats ont mis en evidence que la contamination par differents types de metaux (dont Cu et Pb principalement) a conduit a une alteration de la production des metabolites secondaires des racines, tiges et feuilles de la plante hyperaccumulatrice Pteris vittata et que concernant les racines des tendances similaires dans les changements metaboliques ont pu etre observes dans un autre type de contexte de pollution (Zn et Pb plus...
2014
« C'est le chemin du cactus qui mène à la gloire et non le chemin de jasmin » Fayza et Salima Dédicaces Mes très chers parents : Puisse ce modeste travail constituer une légère compensation pour tous les nobles sacrifices pour assurer mon bien être et mon éducation, vous m'avez toujours encouragé et soutenu, merci pour votre confiance et votre amour. A Mes très chers frères Avec qui j'ai passé les meilleurs moments de mon existence : Mokrane, Hakim et Nadir A Ma très chère soeur Nadjet que j'adore Mes dédicaces sont également adressées à tous mes cousins et cousines A Mes chères copines : Hadjila,
Agrosystèmes légumiers : les plantes de service contre les bioagresseurs
Infos CTIFL, 2020
Filière légumière et transition agroécologique Action directe des plantes de service sur les bioagresseurs Action indirecte des plantes de service via les auxiliaires Multiservices, combinaison de services, disservices Pratiques culturales associées aux plantes de service Plantes de service : méthode innovante et alternative Bibliographie HORS-SÉRIE NOVEMBRE 2020
2014
Un champignon phytopathogène du genre Fusarium F-02 est isolé de la tomate pourrie. L'isolat de ce champignon se révèle virulent pour les plantes de tomate, de concombre et de haricot. Testé in vitro, cet isolat inhibe significativement la germination et la croissance racinaire de ces trois plantes, et in vivo, le taux de mortalité des plantes contaminées par cet isolat est plus élevé par rapport à celui des plantes non contaminées. Parmi les 87 isolats d'actinomycètes provenant des sols rhizosphériques de plantes d'haricot, de tomate et de concombre, 24 sont antagonistes de F-02 et les pouvoirs inhibiteurs de ces isolats varient entre 14% et 60%. L'isolat d'actinomycète Ac66, isolé du sol rhizosphérique de la plante d' haricot a montré une inhibition élevée de 60,52%. Le traitement des graines de plantes à germer avec la solution de l'isolat Ac66 attenue significativement la virulence de F-02 in vivo. Mots-clés : lutte biologique, actinomycètes, antagoni...
Http Www Theses Fr, 2013
Biocontrol research based on the use of microorganisms is expanding very rapidly. However, the use of such bioncontrol agents is still too inconsistent to effectively protect plants in field applications. This phenomenon is often attributed to the non-persistence of biocontrol agents in the rhizosphere or on the plants. In order to reduce the risk of this happening, one solution consists in using microorganisms that are isolated from the plants needing protection. In this thesis, an oomycete called Pythium oligandrum, which colonizes the rhizosphere of many plants, including grapevine, was assessed for the control of esca, a grapevine trunk disease for which no control method is currently available. P. oligandrum strains have been isolated from the rhizosphere of vines cultivated in 3 winegrowing regions (12 grapevines) of Bordeaux with different types of soil: stony-sandy, silty and stony. Analyses of fungal and bacterial communities using a molecular fingerprinting method (Single Strand Conformation Polymorphism) showed that, unlike bacteria, the fungal species varied according to the sampling region. Roots of all the vines sampled were colonized by echinulated-oospore Pythium spp., with P. oligandrum strains predominating. Phylogenetic analyses based on the genes encoding the cytochrome oxidase I and one tubulin allowed these strains to be clustered into three groups. The sequencing of the elicitin-like genes, whose proteins are key components in inducing systemic resistance in plants, showed that each strain held at least one gene encoding for each of the two kinds of P. oligandrum elicitors (i.e. oligandrin and Cell Wall Proteins). Sequencing and molecular fingerprinting analyses showed thus that the type of soil and the rhizosphere microbiota did not shape the population structure of P. oligandrum. However, other factors such as the different kinds of rootstock and weeding management can also have an influence on the root colonization by P. oligandrum. The relationship between P. oligandrum and grapevine was studied using a transcriptomic approach (microarray Vitis vinifera, 29 549 genes). The results highlighted the modifications induced by young vines in response to P. oligandrum root colonization, in the genetic expression of several genes belonging to different metabolic pathways. Two aspects, that are usually opposed, were observed: P. oligandrum was perceived by the plant either (i) as a pathogen because certain defence reactions were triggered (e.g. calcium signalling, resistance genes, abscissic acid metabolism) or as (ii) a symbiotic microorganism since several transcriptional changes were similar to those reported in symbiotic interactions (e.g. induction of subtilase genes). An assay aimed at protecting grapevine against a pathogenic fungus involved in esca, and known to be responsible for wood necrosis, i.e. Phaeomoniella chlamydospora, was carried out. The root colonization by P. oligandrum was associated with a reduction in the length of necroses. In line with this result, transcriptomic analyses by microarrays and RT-qPCR showed overexpression of several genes, particularly those of the ethylene pathway. Some of these induced genes could be thus used as resistance markers, but this needs to be validated in further experiments.
Des champignons pour réhabiliter les sols pollués
Biofutur, 1997
Desmpignons ' pour rkhabiliter ' * Inra, laboratoire biotechnologie des champignons filamenteux. ESIL-CESB, CP 925,163 av de Luminy. 13288 Marseille cedex 99. ** Inra. unite phytopharmacie et mediateurs chimiques, rte de Saint-Cyr, 78026 Versailles cedex.
Lutte biologique contre les acariens phytophages
2011
Dans un triple souci d'efficacite de la protection phytosanitaire, d'economie et d'une gestion phytosanitaire plus respectueuse de la sante et de l'environnement, l'utilisation massive de produits phytosanitaires a peu a peu ete raisonnee et limitee (premieres lignes)
Les Méthodes Moléculaires Pour La Caractérisation Des Champignons Phytopathogènes
European Scientific Journal, 2016
Development of new disease-resistant varieties and the development of epidemic control strategies, require knowledge of the molecular structure and genetic relationships among the pathogen populations. Molecular methods are used to explore the diversity at the DNA level. In fact, they highlight molecular markers which are independent of the host selection, allowing study of biodiversity on the genome. These markers are most effective than a virulence markers, consequently they has become widely used in the plant pathology laboratories. This mini-review summarized the main molecular methods used; the paper describe for each one, the principle, the sequenced steps, then the advantages or inconveniences.