Teses / dissertações sobre o tema "Blé – Maladies – Lutte biologique contre"
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Leroy, Valentin. "Décontamination des grains de blé et d'orge par traitements aux ultrasons". Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27917.
Platel, Rémi. "Criblage, efficacité et modes d’action de composés de biocontrôle microbiens sur le pathosystème blé-Zymoseptoria tritici". Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2021/2021LILUR025.pdf.
Septoria Tritici Blotch, caused by the hemibiotrophic fungus Zymoseptoria tritici, is one of the most severe diseases on wheat, responsible for yield losses up to 50%. Currently, strategies used to control this disease rely mainly on the use of chemical fungicides, and to a lower extent, on the use of partially resistant cultivars. Nevertheless, because of the pathogen resistances and an increasing social demand to reduce conventional pesticides in agriculture, new agroecological alternative crop protection methods, like biocontrol, must be developed. The main purpose of this thesis project was, therefore, to identify new effective biocontrol compounds on the wheat-Z. tritici pathosystem and to decipher their modes of action. An in vitro screening of a panel of 181 microbial compounds (fungal and bacterial extracts, rhamnolipids, lipopeptides…) was performed to assess their antifungal activity towards the pathogenic agent. The most active compounds were selected for further experiments, such as verifying their protection activity in planta. The ability of 19 rhamnolipids (RLs) to control the pathogen was explored and a structure-activity relationship study revealed that bioinspired RLs with ether or ester links and a 12 carbon hydrophobic fatty acid tail were the most effective for all tested biological activities (biocide activity, wheat defense elicitation and protection efficacy). Among them, Rh-Est-C12 was the most promising compound, with a protection efficacy of 78.9%. The potential of Rh-Est-C12 as well as mycosubtilin, a lipopeptide also effective to protect wheat against Z. tritici, to induce host defenses was investigated using a combined transcriptomic and metabolomic approach. The RL did not trigger any major disorganization of the wheat leaf physiology, hence it would protect the host mainly through its direct activity towards Z. tritici while mycosubtilin would display a dual mode of action, antifungal effect and wheat priming. Mycosubtilin could prime wheat by interacting with its plasma membranes leading to flavonoids accumulation and other abscisic acid dependent responses. New insights in wheat defense mechanisms towards Z. tritici were reported. Finally, two Bacillus velezensis strains, isolated from wheat phyllosphere, displayed promising antifungal effect towards the pathogenic agent. Characterization of their metabolites was performed and the putative role of bacillomycin D molecule family as a potent Z. tritici antifungal lipopeptide was highlighted
Dutilloy, Emma. "Biocontrôle des maladies du blé et de l'orge à l'aide de bactéries bénéfiques". Electronic Thesis or Diss., Reims, 2023. http://www.theses.fr/2023REIMS070.
Wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) are among the main cereals cultivated worldwide due to their economic and social significance. However, their yield can drop by more than 40% when infected by the ascospore Zymoseptoria tritici, causing wheat septoria, and by Pyrenophora teres, which causes net blotch. Therefore, to reduce the use of pesticides, this project aimed to identify a strain that can significantly reduce the symptoms caused by these two pathogens. The strain Bacillus velezensis BE2 DSM115797 was chosen for its antifungal properties, both in vitro and in planta. An in-depth study of the mechanisms of action revealed that, when applied to the roots of wheat and barley, the bacterium significantly reduced leaf symptoms, inducing systemic resistance in the plant. Transcriptomic and metabolomic studies confirmed that the bacteria, once applied, did not trigger an immediate response in the plant. However, after a pathogenic infection, plants inoculated with the BE2 strain showed a more pronounced activation of their defense mechanisms, leading to a potentiating effect in the plant. At the bacterial level, a direct antagonism was also demonstrated with the identification of secondary metabolites that have antifungal effects on both fungi. Moreover, the production of these metabolites varied based on the presence of the pathogens
Alaphilippe, Aude. "Effets secondaires de l'utilisation d'un agent de lutte biologique : rôle des metabolites primaires de surfaces des feuilles dans l'interaction entre l'agent de lutte biologique et Cydia pomonella L". Paris, AgroParisTech, 2008. http://www.theses.fr/2008AGPT0039.
Masih, Emmanuel Isaac. "Lutte biologique contre Botrytis cinerea, agent de la pourriture grise de la vigne". Dijon, 2005. http://www.theses.fr/2005DIJOS049.
Grey mould disease caused by Botrytis cinerea is one of the most important diseases of the grapevine. The intensive use of the chemical products to irradicate the grey mould disease resulted in environmental pollution, and appearence of the resistant varieties of the pathogen. This study of research showed the antagonism between the B. Cinerea and the bacteria and yeast, and the different isolates of the genus Pythium. The selected antagonistic microbes to Botrytis cinerea, were identified using morphological as well as genetical tools and the study of their mode of action was initiated. The enzymatic activities and the elicitation capability were also studied. These activities have a direct relationship with the trigerring of the natural defence mechanisms of the grapevine. In the following context, the use of the selected micorobes as biocontrol agents can be undertaken for the effective control of Botrytis cinerea
Sy, Abdoul Aziz. "Lutte biologique contre la pyriculariose du riz (Pyricularia oryzae cav. ) : stratégie et applications". Toulouse, INPT, 1987. http://www.theses.fr/1987INPT025A.
Pelat, Thibaut. "Obtention et ingénierie d'anticorps recombinants thérapeutiques et/ou prophylactiques dirigés contre les agents du risque biologique provoqué". Montpellier 2, 2009. http://www.theses.fr/2009MON20093.
Recombinant antibodies isolated from non-human primates represent very promising medical countermeasures against bioweapons. The advantages and methodological aspects of this approach have been described. An scFv, neutralizing the lethal toxin of Bacillus anthracis (2LF: KD= 1. 02 nM) and directed against the “lethal factor” subunit was isolated from a phage-displayed immune library, and characterised. Another scFv, 43RCA, neutralizing ricin, was obtained with the same methodology and tested (in particular: KD= 40 pM). This approach may also be used beyond bioweapons, as an scFv directed toward Aspergillus fumigatus was also isolated (MS130i-IIIC3: KD= 0,96 nM). On-line sequence analysis with IMGT tools allowed to show the high degree of similarity between these scFvs and their human counterparts. Antibody fragments were engineered, including an in vitro affinity maturation (KD initial = 3. 4 nM; KD final = 0. 18 nM). Utilizing IMGT standardisation and on-line tools, a “germline humanization” - utilizing FR derived from IgM, encountered by every Human, as opposed to IgG FR - was realized in order to ensure an optimal tolerance for one of our scFvs. A primatized IgG was tested in vivo and showed therapeutic and prophylactic capacities
Tachapattaworakul, Thunwadee. "Optimisation de la culture et de la traçabilité de la culture de Trichoderma atroviride destiné à la lutte biologique". Montpellier 2, 2006. http://www.theses.fr/2006MON20076.
Demeule, Elizabeth. "Effet répressif de Bacillus subtilis et de Bacillus pumilus envers Rhizoctonia solani sur tomate et concombre de serre". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/66758.
Besset-Manzoni, Yoann. "Améliorer les principes de sélection de nouveaux agents bactériens de biocontrôle contre la fusariose du blé". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1124/document.
To combat pests of crops (herbivores and pathogens) new pathways have been explored, in particular biological control. Used the nature and its organisms to regulate the populations of pathogens, that is the goal of the biological fight also called biocontrol. Among the organisms commonly found in biocontrol are micro-organisms, be they fungi or bacteria. These microorganisms have very interesting capabilities for farmers and agronomists. Indeed, studies have shown that they are able to interact with plants to allow a better growth and health of it.Then, in this thesis, we were interested in bacteria to find alternative methods of struggle with Fusarium graminearum, a pathogen of cereals responsible for high yield losses, especially thanks to the production of mycotoxins that will make the seeds unfit for human and animal consumption.Through an original approach of keeping noninhibitory strains in vitro for in planta tests, we have been able to show the limitations of in vitro selection. Thanks to the metabolic exploration of a particularly efficient strain, we have also been able to highlight potential new antifungal molecules. Through a model strain, we explored the mechanisms of the establishment of systemic resistance in wheat induced by bacteria. And finally, we have explored the potential of bacterial combinations in wheat protection that seems to represent a real future in the world of biocontrol.The work done is in line with the needs of new resources to limit the use of pesticides, but also in a need to better understand the tripartite interactions between wheat, pathogen and beneficial bacteria
Samain, Erika. "Étude des interactions PGPRs/génotypes de blé tendre dans la lutte contre la septoriose". Thesis, Amiens, 2019. http://www.theses.fr/2019AMIE0027.
Septoria tritici leaf blotch (STB) caused by Mycosphaerella graminicola is regarding as the most important disease in wheat. The present work aims to study the durability and efficiency of the plant-growth-promoting rhizobacteria (PGPR)-induced resistance (IR) against STB. Many of PGPR were screened, in single and co-inoculations, for their root colonization, plant growth promotion (PGP) and IR, using different wheat genotypes. However, two effective PGPR-mixtures were identified, Mix2; Paenibacillus sp. strain B2 (PB2) with an effective approval strain AA and Mix3; PB2 with Microbacterium SSM001 and Arthrobacter SSM004, in equal portions. PGPR in Mix2 and Mix3 showed ecto- and endophytic root colonization until the flag-leaf growth stage (FL), with a helper impact on root colonization by PB2. Only, with Mix2 and 3, PGP was observed. Under drought stress, the IR by Mix2 and 3 was more efficient compared to PB2. However, all of them showed high and durable IR against STB until FL, which seems to be more correlated to PB2 and depends on plant-genotype, growth-stage and M. graminicola strain. Interestingly, the high PGPR-IR against STB was confirmed under field conditions. Using the non-sterile field soil, they didn’t show significant impact on the soil microbial communities (SMC), using the 16S rDNA and ITS MEGA sequencing. But, a significant reduction in the PGPR’ efficiency was recorded, only, for PB2 and Mix3, and in some tested cultivars. Gene expression analysis of the PB2-, Mix2- and Mix3-IR showed upregulations of gene markers involved in the basal defenses, JA, phenylpropanoids & phytoalexins and ROS pathways, with stable priming inductions of Pr1, glucanase, and flavonoide, suggesting them as protection markers. We identified an effective PGPR-mixture induces high and durable and stable resistance against STB and drought stresses, promotes plant growth, and without disturbance on the SMC. The global results may help to reduce gap between laboratory and field results
Bouchard-Rochette, Mathieu, e Mathieu Bouchard-Rochette. "Bacillus pumilus et Bacillus subtilis pour lutter contre la pourriture grise chez la tomate et le concombre de serre". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38128.
Cette étude s’inscrit dans le cadre d’un programme de recherche destiné à évaluer le potentiel d’utilisation en horticulture des bactéries Bacillus pumilus souche PTB180 et Bacillus subtilis souche PTB185. Elle avait pour objectifs (1) d’évaluer in vitro l’activité antagoniste contre Botrytis cinerea des souches PTB180 et PTB185, (2) d’estimer leur capacité à survivre sur la phyllosphère de la tomate et du concombre et 3) d’évaluer leur effet sur le développement de la pourriture grise (B. cinerea) sur des plants de tomate et de concombre cultivés en serre. L'activité antagoniste de PTB180 et PTB185 a été évaluée en boîtes de Pétri sur géloses, sur tissus foliaires de tomate et de concombre et sur fruits de tomate. Les deux souches ont inhibé très fortement la croissance mycélienne et la germination des spores de B. cinerea sur géloses. Sur feuilles de tomate et sur disques foliaires de concombre, PTB185 et le mélange (1:1) des deux souches ont réduit significativement (p ≤ 0,01) la croissance mycélienne de B. cinerea comparativement aux témoins. PTB180 a réprimé significativement la croissance mycélienne de B. cinerea sur les fruits de tomate. Afin d'estimer la survie de PTB180 et PTB185 sur la phyllosphère, des plants de tomate et de concombre ont été pulvérisés jusqu'à ruissellement avec une suspension (1×107 unités formatrices de colonies [UFC]/mL) de PTB180, PTB185 ou d'un mélange (1:1) des deux souches. Les populations de chaque souche ont ensuite été suivies au cours du temps sur les feuilles. Les résultats obtenus montrent que les souches survivent au moins 21 jours sur les plants de tomate et de concombre avec un taux de survie variant de 43% à 100%. De plus, pratiquement aucune variation dans les proportions de chaque souche n'a été observée au fil du temps lorsque PTB180 et PTB185 étaient appliquées en mélange. Enfin, l’application foliaire de PTB180, PTB185 et du mélange (1:1) des deux souches a permis une réduction significative de l’incidence et de la sévérité de la pourriture grise chez des plants de tomate et de concombre inoculés avec B. cinerea et cultivés en serre. Les souches PTB180 et PTB185 ont montré au cours de cette étude une forte activité antagoniste envers B. cinerea, la capacité de survivre sur la phyllosphère de plants de tomate et de concombre et de réprimer le développement de la pourriture grise chez ces derniers. Ces souches pourraient éventuellement être utilisées comme agents de lutte biologique contre la pourriture grise du concombre et de la tomate de serre.
Bourgouin, Catherine. "Les Toxines de Bacillus thuringiensis israelensis et de Bacillus sphaericus leur utilisation en lutte biologique contre les vecteurs de maladies tropicales /". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376121877.
Ali-Haimoud, Djamel-Eddine. "Contribution à l'étude de la lutte biologique contre Drechslera teres (Sacc. ) Shoem. , parasite de l'orge". Toulouse, INPT, 1994. http://www.theses.fr/1994INPT007A.
Bouchard-Rochette, Mathieu. "Bacillus pumilus et Bacillus subtilis pour lutter contre la pourriture grise chez la tomate et le concombre de serre". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38128.
Mousques, Adeline. "Mise en évidence d'une nouvelle substance antifongique produite par une souche de Pseudomonas cepacia isolée du sol : action sur Botrytis Cinerea". Bordeaux 2, 1996. http://www.theses.fr/1996BOR20446.
Barrera, Gaytan Juan Francisco. "Dynamique des populations du scolyte des fruits du caféier, hypothenemus hampei (Coléoptera : Scolytidae), et lutte biologique avec le parasitoi͏̈de Cephalonomia stephanoderis (Hymenoptera : Bethylidae), au Chiapas, Mexique". Toulouse 3, 1994. http://www.theses.fr/1994TOU30085.
Pichard, Brigitte. "Bacillus polymyxa, inhibiteur de parasites microbiens du chou-fleur". Brest, 1992. http://www.theses.fr/1992BRES2018.
Gravel, Valérie. "Lutte contre Pythium ultimum chez la tomate de serre : une approche microbienne". Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24523/24523.pdf.
St-Laurent, Marianne. "Amélioration de la lutte biologique contre le tétranyque à deux points en framboisières sous grands tunnels : essais d'un supplément nutritif, de plantes-réservoirs et de brumisation". Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/29866.
High tunnels show many benefits for raspberry production, including increased yield and improved fruit quality. However, this crop management approach also provides an environment that fosters outbreaks of the two-spotted spider mite, Tetranychus urticae. Although some miticides are available, pre-harvest application intervals and pesticide resistance development can be problematic. Phytoseiid predatory mites, such as Neoseiulus fallacis, are recognized for their efficacy in controlling spider mites. However, repeated introductions often must be made during a season, resulting in significant cost. To reduce these costs and thereby make biological control more attractive to growers, we tested a food supplement for predators, a banker plant and misting. The main objective of this study was to improve the effectiveness of integrated control against spider mites while decreasing the number of predator introductions in raspberry production under high tunnels. The specific objectives were to determine the effectiveness of four integrated pest management (IPM) strategies in raspberry under high tunnels and estimate their cost ($ / ha) in comparison to conventional control (mitices only) methods. The tested approaches combined different strategies: introduction of Neoseiulus fallacis predators; addition of Sorbaria sorbifolia as a banker plant; use of a pollen-based food supplement for predators, “Nutrimite", from Biobest; and misting. Tests were conducted at two raspberry farms in the greater Quebec City (Quebec, Canada) area. Data collected by monitoring populations of both spider mites and predators show that the pollen supplement has a positive effect on the predatory ability of N. fallacis and that misting tends to reduce T. urticae densities.
Fruit, Laetitia. "Etude des facteurs d'efficacité d'un agent de lutte biologique (Ulocladium atrum) pour la protection des plaies d'effeuillage sur tomate contre Botrytis cinerea". Lyon 1, 2001. http://www.theses.fr/2001LYO10030.
Babi, Adnan. "Bioécologie de Trichogramma Cacoeciae Marchal et T. Daumalae Dugats et Voegele (Hym. Trichogrammatidae) : utilisation en lutte biologique contre Lobesia Botrana Den. et Schief. (Lef. Tortricidae)". Aix-Marseille 3, 1990. http://www.theses.fr/1990AIX30032.
Allaire, Mathieu, e Mathieu Allaire. "Diversité fonctionnelle des Pseudomonas producteurs d'antibiotiques dans les rhizosphères de conifères en pépinières et en milieu naturel". Master's thesis, Université Laval, 2005. http://hdl.handle.net/20.500.11794/18046.
La production de millions de semis voués à la reforestation est affectée par les problèmes de pourritures racinaires. Afin de développer des agents de biocontrôle adaptés aux pépinières, nous criblons les populations de Pseudomonas spp. des rhizosphères d’épinettes provenant de pépinières et de milieu naturel, pour détecter des gènes de production d’antibiotiques. Nous avons isolé plusieurs souches portant des gènes de production de phloroglucinol, de pyrrolnitrine, de cyanure d’hydrogène et de phénazines. L’analyse de ces gènes montre que pour les producteurs de phloroglucinol, un génotype est dominant dans les pépinières, alors qu’un génotype différent est dominant chez les souches provenant de milieu naturel. Ces dernières possèdent également les gènes de synthèse de la pyrrolnitrine et leur capacité d’inhiber Cylindrocladium floridanum in vitro est supérieur. De plus, en se basant sur la séquence du gène phzC, nous avons isolé trois groupes de producteurs de phénazines, dont deux provenant de milieu naturel et un de pépinière. L’analyse du gène de la portion 16s de l’ARN ribosomal confirme que ces trois groupes appartiennent à différente espèces.
Fluorescent Pseudomonas spp. that produce antibiotics such as 2,4-diacetylphloroglucinol and phenazines show biocontrol activity against many important soil borne fungal pathogens. We isolated several strains of Pseudomonas carrying genes for DAPG and PCA synthesis from the rhizosphere of black spruce (Picea mariana) and white spruce (Picea glauca) in two different conifer nurseries and in one natural stand. Sequence analysis of a portion of the phlD gene revealed that one dominant genotype was present in both nurseries and that a different genotype was dominant in the natural forest. Strains from the natural forestwere also found to have the genes for pyrrolnitrin synthesis but lack pyoluteorin biosynthesis genes. Furthermore, in vitro anitfungal assays against Cylindrocladium floridanum showed a much stronger inhibition by strains isolated from natural forest than from nursery. Analysis of phenazine genes revealed 3 groups of phenazines-producers; one from a nursery and two from natural stand.
Fluorescent Pseudomonas spp. that produce antibiotics such as 2,4-diacetylphloroglucinol and phenazines show biocontrol activity against many important soil borne fungal pathogens. We isolated several strains of Pseudomonas carrying genes for DAPG and PCA synthesis from the rhizosphere of black spruce (Picea mariana) and white spruce (Picea glauca) in two different conifer nurseries and in one natural stand. Sequence analysis of a portion of the phlD gene revealed that one dominant genotype was present in both nurseries and that a different genotype was dominant in the natural forest. Strains from the natural forestwere also found to have the genes for pyrrolnitrin synthesis but lack pyoluteorin biosynthesis genes. Furthermore, in vitro anitfungal assays against Cylindrocladium floridanum showed a much stronger inhibition by strains isolated from natural forest than from nursery. Analysis of phenazine genes revealed 3 groups of phenazines-producers; one from a nursery and two from natural stand.
de, Ladurantaye Yannick. "Définition des critères d'entreposage, de transport et de distribution au champ du Perillus bioculatus, un prédateur naturel du doryphore de la pomme de terre". Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25352/25352.pdf.
La, Broise Denis de. "Croissance et sporulation de Fusarium oxysporum en milieux liquides et solides : étude des facteurs limitants et application à la production industrielle de spores pour la protection des cultures". Compiègne, 1988. http://www.theses.fr/1988COMPD131.
Pellan, Lucile. "Décryptage des mécanismes impliqués dans le biocontrôle des champignons mycotoxinogènes des céréales". Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTG036.
Deciphering the mechanisms involved in the biocontrol of mycotoxinogenic fungi of cereals.Cereals are the first factor of consumer exposure to mycotoxins, toxic secondary metabolites synthesized by particular moulds and which present a risk for human and animal health. The species Fusarium graminearum and Fusarium verticillioides are thus responsible for the production of trichothecenes and fumonisin-like mycotoxins, respectively, with a high impact especially in pre-harvest. With the decrease of pesticide use due to their toxicity, an alternative strategy to control these fungal diseases in the field may be the use of antagonistic microorganisms. Non-pathogenic, these biocontrol agents (BCAs) are able to limit the progression of Fusaria and their synthesis of mycotoxins through various biological mechanisms, however still poorly understood. In this context, the objectives of this study are to evaluate by which mechanisms three selected BCAs (Streptomyces griseoviridis, Trichoderma asperellum, Pythium oligandrum) can modulate the growth and mycotoxin production of Fusarium pathogens, in vitro and in situ. Antagonistic activities and varying levels of inhibition of growth (up to 80%) and mycotoxinogenesis (up to 90%) have been observed in vitro depending on BCAs, pathogens or culture conditions. The hypotheses are then verified and completed thanks to the development of a toolbox of tests specific to certain modes of action. Their chronology is evaluated throughout the interaction, from pathogenic spore germination to the formation of perithecia, by testing a wide variety of BCA mechanisms: synthesis of anti-germinative compounds, mycophagy, chitinolytic enzyme synthesis, emission of volatile antifungal compounds, inhibition of mycotoxin biosynthesis pathways, mycotoxin bio-transformation, spatial and nutritional competition or impact on pathogen conservation. S. griseoviridis presents nutritional competition capacities, but its main strategy is based on antibiosis, through the synthesis of numerous antifungal compounds that offsets a significant deficit in spatial colonization capacity. However, it can stimulate the mycotoxin production. T. asperellum is capable of activating a very wide range of defenses and attacks combining the synthesis of various antifungal compounds (metabolite, enzymes, VOCs), with different targets (spores, mycelium, mycotoxins), and a direct action by mycoparasitism. The efficacy of P. oligandrum is mainly due to its strong capacity to colonize the environment, with a direct action via microbial predation and reduction of perithecia formation. These in vitro performances could also be analyzed in F. graminearum in situ throughout its life cycle (from colonization of ears to survival in culture residues), and put into perspective with the different modes of action identified in each of the BCAs. The whole project has led to important advances in deciphering the mechanisms of action of BCAs and proposes ways of improvement to optimize the use and efficacy of these antagonists. Thus limit the use of chemical plant protection products, while maintaining a healthy production with low levels of mycotoxins
Gerbore, Jonathan. "Lutte biologique contre un champignon pathogène impliqué dans l’esca de la vigne, par utilisation de l’oomycète Pythium oligandrum". Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3037/document.
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 wine-growing 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
Lemaire, Émilie. "LA LUTTE BIOLOGIQUE CONTRE LES TÉTRANYQUES DANS LES FRAMBOISIÈRES SOUS TUNNELS : Introduction d’acariens phytoséiides et modèle de simulation dynamique". Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/28742/28742.pdf.
The main objective of this project was to evaluate the effectiveness of releases of phytoseiid predatory mites (Neoseiulus fallacis, N. californicus and Phytoseiulus persimilis) to suppress spider mites in high tunnel raspberries. Results suggested that phytoseiid releases are a realistic way to control spider mites and to reduce the use of acaricide in this new production system without compromising the quality of the crop. However, temperature and humidity conditions must be suitable to achieve successful establishment of predators and release rates must be sufficiently high to promote acceptable pest control. The second objective was to model the evolution of mite populations to better understand the dynamics observed under tunnels. The model developed describes the spider mite outbreak and abundance over time with a good fit. It shows that higher temperature under tunnel is a critical parameter governing predation and spider mite population increase.
Morais, David. "Les déterminants des phases épidémiques précoces de la septoriose du blé (Zymoseptoria tritici) : quantité, efficacité et origine de l'inoculum primaire". Electronic Thesis or Diss., Paris, AgroParisTech, 2015. http://www.theses.fr/2015AGPT0021.
Fungal foliar diseases are a major constraint to cereal production systems. They constitute relevant models to elucidate how an epidemic begins, which is a recurrent question in plant disease epidemiology. In this thesis three of the main components of the early stages of the epidemics of septoria tritici blotch, a wheat disease caused by Zymoseptoria tritici, were studied: the quantity, the efficiency and the origin of primary inoculum. The study focused on epidemics occurring over the 2011-2013 cultural seasons in two wheat plots located close to each other in Grignon (France). The first plot, characterized by the absence of debris, was exposed to distant sources of primary inoculum, while the second plot, grown in wheat for several years, had a large amount of contaminated debris acting as a local source of primary inoculum. In the first part of the thesis, ascospore trapping using a volumetric spore trap combined with DNA quantification by qPCR allowed to quantify the inoculums present in the air above the wheat plots during the early stages of the epidemics. The limits of detection and quantification were determined, discussed and used to estimate small amounts of ascospores. Neither the local presence of contaminated debris nor the quantity of inoculum above the plots was correlated with the earliness of the epidemics. In the second part, the pathogenicity of Z. tritici ascospores and pycnidiospores was estimated on adult plants. The latent period following infections by ascospores was 60 degree-days longer than following infection by pycnidiospores. In the third part of the thesis, which aimed to identify the source of primary inoculum, two strategies were developed. The first strategy investigated changes in the genetic structure of different subpopulations collected from both wheat plots over a period of three years using neutral markers (SSR). No structure was identified, but slight differentiations in some subpopulations, consistent with the epidemiological context (nature of the reproduction cycle from which they derived, epidemic period, disease intensity) were highlighted. These results, however, did not allow to determine the origin of the primary inoculum because no difference between resident (local) and immigrant (distant) subpopulations, or a genetic discontinuity between subpopulations from the end (season n) and the beginning of epidemics (season n + 1), were identified. The second strategy compared the aggressiveness profile (sporulation capacity and latent period) of a Z. tritici population collected at the beginning of an epidemic in the monoculture wheat plot and of a resident population (ascospores ejected from debris present in the plot) and to an immigrant population (leaf lesions caused by ascospores of distant origin). The profile of the tested population, closer to that of the resident population, suggested that the epidemic was mainly initiated by primary inoculum of local origin. This case study showed that a quantitative management (reduction) of the primary inoculum would be probably inefficient, while its qualitative management, taking into account the differential adaptation of pathogen populations to their hosts, deserves to be taken into account in crop protection strategies (alternating wheat cultivars in time). Finally, the definition of the beginning and the end of an epidemic was discussed, depending if we consider an annual scale (absence of the host as a beginning or end criterion) or a multiannual scale (pathogen pressure discontinuity as the beginning or end criterion, regardless of the absence of the host)
Jousse, Cyril. "Contribution à la lutte contre les maladies du bois de la vigne, en particulier l'esca". Phd thesis, Université de Poitiers, 2006. http://tel.archives-ouvertes.fr/tel-00185265.
Nous avons étudié les propriétés de PA, PC et EL, en particulier l'impact sur leur croissance de fongicides commerciaux et de fongicides systémiques synthétisés au laboratoire, ainsi que de molécules naturelles. Ces pathogènes ne présentent pas la même sensibilité à ces molécules et l'un d'eux (PA) est peu affecté par divers traitements. En parallèle, nous avons étudié les propriétés d'ambimobilité de l'acide salicylique (AS) et de quelques-uns de ses dérivés halogénés.
Nous avons montré que F 30, un dérivé acide du fenpiclonil, est mobile dans les boutures de vigne après application foliaire. Il est en partie retenu dans le bois et libère la molécule parent dans les racines. L'acide 5-chlorosalicylique (5-ClAS), connu pour être plus actif que AS pour stimuler les défenses naturelles, présente une mobilité voisine de celle de AS. Sur ces bases, F 30 et 5-ClAS ont été retenus pour des tests préliminaires de traitement par voie foliaire de boutures de vigne infectées.
Cette recherche exploratoire souligne la complexité de la problématique, une lutte chimique (fongicide), génératrice de contraintes, devant s'intégrer dans une stratégie globale de contrôle.
Expert, Jean-Michel. "Lutte biologique contre les attaques précoces de Sclerotinia sclerotiorum du tournesol à l'aide de Pseudomonas spp. Fluorescents et de Bacillus spp". Lyon 1, 1995. http://www.theses.fr/1995LYO10221.
Pronier, Isabelle. "Etude biologique des interactions entre une nouvelle souche de virus et son hôte : la tordeuse à bandes obliques (Choristoneura rosaceana, Lepidoptera, Tortricidæ). Implications dans des perspectives de lutte biologique". Amiens, 2000. http://www.theses.fr/2000AMIE0108.
Outbreak of some obliquebanded leafroller populations, a Lepidopteran species that attacks cultivated fruit througthout North America, in spite of insecticide treatments, calls for alternative control methods. Our work focused on biological control in the context of Integrated Pest Management. The biocontrol agent is a new strain of nuclear polyhedrosis virus (NPV), isolated from C. Rosaceana larvae collected in an apple orchard in Quebec. Variability and plasticity on levels of larval sensibility to azinphosmethyl and on larval development in absence of treatment, were studied in a first part. A second part concerns the study of the host - virus System. Using light and electron microscopy, virus determination and its evolution in its host were investigated. Bioassays with different experimental conditions indicated that this viras strain is slow acting. The viral disease is characterized by a long period of latency before the death occurred and during that time, the diseased insect continue to feed. The virus can also induce diapause. The vertical transmission through one generation is low. The results obtained during this work allow to consider the possibilities that this NPV offers as biocontrol agent
Magnin-Robert, Maryline. "Protection de la vigne contre Botrytis cinerea et stimulation des mécanismes de défense à l’aide de bactéries issues du vignoble champenois". Reims, 2007. http://theses.univ-reims.fr/exl-doc/GED00000725.pdf.
The development of new alternatives to chemicals against Botrytis cinerea in grapevine, especially by using bacteria originated from Champagne vineyard is the objective of this thesis. These bacteria isolated from the rhizosphere and from different healthy grapevine organs, are two Acinetobacter lwoffii PTA-113 and PTA-152, a Bacillus subtilis PTA-271, two Pantoea agglomerans PTA-AF1 and PTA-AF2 and two Pseudomonas fluorescens PTA-268 and PTA-CT2. Experiments performed mainly in vineyard demonstrated that these bacteria applied individually or in combination are able to induce defence reactions in grapevine as evidenced by a stimulation of chitinase and β-1,3-glucanase activities in leaves and berries. The intensity of these defence reactions is dependent on bacterial strain, combination of bacteria and their application method. They are associated to an induced protection of both organs against Botrytis cinerea. The most active strains are A. Lwoffi, P. Fluorescens and P. Agglomerans PTA-AF1 in leaves and P. Agglomerans PTA-AF1 and PTA-AF2 in berries. The combination of two P. Agglomerans (AF1+AF2) or P. Agglomerans with B. Subtilis or with A. Lwoffi also lead to a significant protection against B. Cinerea, which is not higher than that obtained with individual bacteria
Crépin, Alexandre. "Développement d'une stratégie de lutte globale ciblant la communication impliquée dans la virulence des bactéries macergènes de la pomme de terre". Rouen, 2012. http://www.theses.fr/2012ROUES004.
Neched, Hassiba. "Étude comparative des traitements de semences sans fongicide chez les céréales à l'aide de l'ozone et de l'oxygène pur". Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/25888.
Seedling blight and root rot are part of cereal diseases of field crops in Quebec. They are caused by two pathogens, Fusarium graminearum and Bipolaris sorokiniana, which contaminate the seed grain, especially wheat and barley, which causes both decreased, lift and lower performance. Organic farmers are trying to find a seed without fungicide treatment to fight against these fungi, which are harmful to cereal farming. Our project has as goal to use the oxidative action of oxygen or ozone moistened to cause oxidative stress in order to reduce the impact of the two pathogens responsible for this disease, F. graminearum and B. sorokiniana, while preserving the germinability of the seeds. The dose in oxidizing agent, the flow of oxidizing gases (ozone and/or oxygen) and the time of exposure are key parameters to optimize for this oxidative treatment and germination kinetics treated cereal seed. Such treatment looked promising for the seed of wheat. It was however a little less for the seed of barley because it’s fairly rigid envelope which made difficult the penetration of ozone and oxygen. To remedy this problem, we have preliminary tests on barley using sonication ultrasonic as pre-treatment of barley oxidative pre-treatment. The results suggest that, such treatment is promising and significant in order to optimize our oxidative treatment and subsequently, reduce the causative agents of disease without harming the quality of cereal seed. This point has been addressed in our work by a preliminary test on barley, and this approach looks very promising for our future research.
Marel, Marine. "Lutte biologique contre le tétranyque à deux points (Acari: Tetranychidae) sur le rosier : lâchers de phytoséiides et échantillonnage binominal des tétranyques". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/27790/27790.pdf.
Phytoseiid and spider mites are poorly studied in nursery systems. The objectives of this study were 1) to test the efficacy of combined versus single releases of these two predaceous mite species, Neoseiulus fallacis Garman and N. californicus Mc Gregor, for the suppression of the twospotted spider mite, Tetranychus urticae Koch on roses (Rosa rugosa); and 2) to develop a sampling method for spider mites on R. rugosa. The first objective was tested in the greenhouse. Our results showed a similar efficacy for the monospecific releases and the combined releases; and 2) equivalent proportion of occurrence at which N. californicus and N. fallacis were found on individual plants, suggesting that these two predatory species are compatible. The second objective was tested in the field. We found that the proportion of infested rose leaflets was highly correlated with spider mite densities; revealing that a binomial sampling method could be developed in the future. Keywords: acarine predators, binomial sampling, biological control, multiples natural ennemis, Neoseiulus fallacis, Neoseiulus californicus, ornamental nursery, Rosa rugosa, Tetranychus urticae, twospotted spider mites.
Moulin, Florence. "Etude des interactions Pythium spp. - Pseudomonas spp. Fluorescents dans la rhizosphère du concombre : application à la lutte biologique en culture hors-sol". Lyon 1, 1994. http://www.theses.fr/1994LYO10098.
Habrylo, Olivier. "Une E. S. T. (Expressed Sequence Tag) conduit à la caractérisation, chez le houblon (Humulus lupulus), de trois inhibiteurs de xyloglucanase dont l’expression est influencée par des facteurs biotiques et abiotiques". Strasbourg, 2011. http://www.theses.fr/2011STRA6143.
Phytopathogenic fungi secrete a powerful arsenal of enzymes potentially active on each polysaccharide layer of the plant cell. As a first line of defense, plant cell walls contain several inhibitors to specifically inhibit the activity of these microbial enzymes. In the present study we describe the identification and characterization of three xyloglucan-specific endoglucanase inhibitor proteins (XEGIPs) from hop (Humulus lupulus). Some evidences have been accumulated about the role of these XEGIPs in plant defense. Starting from an expressed sequence tag three genes were isolated by the rapid amplification of cDNA ends, cloned and corresponding proteins expressed in insect cells. The functions of the proteins were validated by enzymatic activity measurements were performed with xyloglucan as substrate. Inhibitor n°1 and inhibitor n°2 were shown to inhibit the hydrolytic activity of xyloglucan-specific endoglucanase from the fungi Aspergillus aculeatus and Fusarium graminearum. The investigation on target enzymes lead to production, expression and characterization of four unknown GH12 from F. Graminearum. Real-time PCR have shown variations in the spatial distribution of inhibitors and differential expression between hop cultivars. The main lines are the following : inhibitor n°1 is expressed as a result of wounding and inhibitor n°2 is inducible by F. Graminearum. Inhibitor n°3 could be have a physiological function with a positive regulation during the germination stages and in the female hop cones
Jemmali, Lamia. "Stimulateurs des défenses naturelles du blé dur en Tunisie et du blé tendre en France contre la septoriose causée par Zymoseptoria tritici". Thesis, Littoral, 2015. http://www.theses.fr/2015DUNK0455/document.
The durum wheat (Triticum durum Desf, DW) as well as the bread wheat (Triticum aestivum L. em Thell, BW) is strongly affected by septoria leaf blotch (STB) caused by the hemibiotrophic fungus Zymoseptoria tritici. First, the present work was used to study of the compatible interaction wheat-Z-tritici. The study of the compatible interaction among pathosystems BD/St-08-46 Z-tritici strain an BT/TO1193 Z-tritici strain revealed the induction of defense pathways in both studied pathosystems, but with slight differences. Then, the study of the interaction of Z. tritici with a resistant durum wheat cultivar showed the fungus resistance of association is related to the inhibition of the direct penetration, sporulation and the avtivity of the fungal enzymes degrading plant cell walls (endo-β-1,4-xylanase, endo-β-1,3-glucanase and protease). They seem to be strongly related to the severity of Z. tritici in both BW and DW. In addition, this study revealed the involvement of several genes in the resistance of DW against Z. tritici such as PR2 genes (β-1,3-glucanase), Chi 4 precursor (precursor of Class IV chitinase), Pox (peroxidase), Msr (methionine sulfoxide reductase) and Bsil (protease inhibitor). On the other hand, the potential of resistance inducers (RIs) to protect BW and DW against STB disease was evaluated. Three natural extracts based on ascorbic acid (AA), plant cell wall oligosaccharides (Oligos) and brown algae (Ascophyllum nodosum, A. nod.) were tested for the first time on wheat. Their antifungal effect (direct) and the effect of inducing wheat defense mechanisms (indirect) have been well characterized through molecular, biochemical and cytological. We recorded that only AA exhibited a direct effect on spore germination and hyphal growth of Z. tritici associated to the induction of wheat defense mechanisms. However, conferred protection by Oligos and A. nod appears to be exclusively related to their plant defense inducing properties witch promoted the decrease of fungal CWDE activities and sporulation. Moreover, tested SDPs seem to enhance same defense pathways in both wheat species. They could induce the activation of (i) PR proteins, (ii) the antioxidant enzymes (catalase and peroxidase), (iii) the protein PAL and LOX (key enzymes of the phenylpropanoid and octadecanoid pathways, respectively) and (iv) the cytological accumulation of H₂O₂ and polyphenols, were highlighted. Also, they seem to use same pathways involved in durum wheat resistance mecanisms and may even induce a higher response of defense-related genes as PR2, Pox, Msr, ATPase, and Bsil. In general, protection conferred by tested RIs seems to be dependent on their composition, but it remains constant whatever of the wheat species. Similarly, in filed tested RIs conferred as interesting protection against STB associated, in the case of the A. nod and AA, with increased chlorophyll content and improving yield quantity and quality of the susceptible cultivar Karim, while in the resistant cultivar Salim, the application of RIs seems to be useless. In conclusion, protection conferred by tested RIs seems to be dependent on their composition, but it remains constant whatever of the wheat species. The use of RIs may improve the resistance level and yield of susceptible cultivars in order to obtain similar results to the resistant cultivars. Thus, it could replace the use of resistant cultivars especially with the lack of completely resistant cultivars available to farmers in Tunisia
Iraqi, Housseini Abdel Ilah. "Recherches sur la lutte biologique contre fomes lignosus (K1. ) Bres. , parasite de l'hevea, par utilisation de champignons antagonistes". Nancy 1, 1987. http://www.theses.fr/1987NAN10087.
Haddaoui, Olfa. "Étude d'un concept novateur de culture du fraisier en buttes semi-permanentes : évaluation d'un substrat adapté". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38151.
Rousseau, Sophie. "Importance de l'eau libre sur le développement des micro-organismes : application à l'étude de la surmaturation du raisin provoquée par Botrytis cinerea". Bordeaux 2, 2001. http://www.theses.fr/2001BOR20915.
The development of the microflore of healthy and botrytized grapes depends on many factors such as the presence of free water, measured by water activity (aw), and the phenomena of potential interactions between the epiphytic microbial populations. The quantity of water necessary for their in vitro development depends on the type of epiphytic micro organism. Minimum aw values of bacterial strains have been observed to be lower than those obtained on yeast strains. Botrytis cinerea is situated between these two populations, with a minimal aw value of 0,93. A study of the interactions between B. Cinerea and the 17 micro organisms, previously isolated from the surface of the grape, has allowed to identify four different strains of yeasts (Kloeckera apiculata, Metschnikowia pulcherrima, Pichia membranaefaciens and Rhodotorula glutinis) capable of reducing the size of the lesion produced by B. Cinerea to the surface of vegetable tissue. The competition for nutritive elements seems to be the mechanism employed by the yeast strain R. Glutinis, in accordance with the observed attachment of its cells to the mycelial filaments. The aw value at the surface of a grape berry, is strongly influenced by precipitation and, to a lesser extent, by the sugar concentration of healthy grapes or the water content of infected grapes. An interesting prospect would be to couple the reduction of availability of surface water by an application of antagonistic strains of micro organisms to fight against pathogenic fungi. This method seems to be an interesting alternative to the conventional chemical treatments
Mustafa, Ghalia. "Protection du blé contre l'oïdium par des champignons mycorhiziens à arbuscules : mécanismes et optimisation". Thesis, Littoral, 2015. http://www.theses.fr/2015DUNK0388/document.
The use of arbuscular mycorrhizal fungi (AMF) could be an innovative alternative to chemicals against fungal plant diseases. Our work aimed at studying the possible protective effect of arbuscular mycorrhization in the bread wheat (Triticum aestivum L.) against Blumeria graminis f. sp. tritici (Bgt), a biotrophic fungi responsible of wheat powdery mildew, a disease affecting the aerial plant organs. Wheat mycorrhizal inoculation by Funneliformis mosseae (Fm), under controlled and optimized conditions, allowed us to obtain concomitantly a micorrhizal rate of 38%, a significant increase of plant biomass and a protection level against Bgt estimated at 78%. These results suggest the induction of systemic wheat defense reactions resulting from mycorrhization (Mycorrhiza-Induced Resistance - MIR). This protection is linked to an accumulation of phenolic compounds and hydrogen peroxide at the Bgt penetration sites in epidermal leaf cells of mycorrhized wheat plants. Up-regulations of POX, PAL, NPR1 and CH11 genes encoding for defense markers were also pointed out in leaves of mycorrhizal wheat in the absence of Bgt infection. Moreover, our study highlighted the importance of taking into account various parameters to optimize the use of AMF as biocontrol agents. The highest protection against powdery mildew was obtained with a 5-fold reduced phosphorus input compared to that recommended in the field and with the mycorrhizal inoculum Fm, in both a moderately susceptible or a more resistant cultuva
Morin, Chantal. "Étude du potentiel d'une souche albinos de Ceratocystis resinifera pour la protection biologique du bois contre le bleuissement". Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23758/23758.pdf.
Collin, François. "La tolérance du blé (Triticum aestivum L.) à la Septoriose". Thesis, Paris, Institut agronomique, vétérinaire et forestier de France, 2017. http://www.theses.fr/2017IAVF0028/document.
The Septoria tritici blotch disease (STB, pathogen Zymoseptoria tritici) is the most damaging foliar infection of wheat crops in Europe. Disease management strategies include cultivar resistance, disease escape strategy and fungicides. However, these strategies have failed to provide a complete protection of wheat crops. The STB tolerance is a complementary approach which aims to maintain yield in the presence of the symptoms. The tolerance of STB relies on plant physiology and source/sink balance: the sink demand (the grain growth) must be satisfied in spite of reduced source availability (photosynthetic capacity as affected by the STB symptoms on the leaves). The green canopy area, the senescence timing and the grain yield components are interesting potential sources of tolerance that were studied in this project. A data-mining study, one glasshouse experiment and two field experiments were carried out providing complementary insights on STB tolerance mechanisms. The genotype × environment interaction effects on tolerance traits were investigated for two seasons × five locations × nine cultivars datasets. The nitrogen nutrition and metabolism of four doubled-haploid (DH) lines contrasting for STB tolerance were examined in a controlled-glasshouse experiment at UMR ECOSYS (INRA,AgroParisTech) Grignon, France. The source/sink balance of six DH lines contrasting for STB tolerance was also examined according to their responses to a spikelet removal treatment, applied in a field experiment in Hereford, UK. Finally, a field experiment with two fungicide regimes (full disease control and non-target (STB) disease control) probed the STB tolerance of six modern UK winter wheat cultivars in Leicestershire, UK. The main objective was to verify identified potential STB tolerance traits in commercial cultivars. Putative STB tolerance traits have been identified such as the early heading date, the low degree of grain-source limitation of healthy crops during the grain filling phase, the vertical canopy distribution favouring a relatively larger flag-leaf. Results showed these traits might be selectable in wheat breeding without a trade-off with the potential yield. Finally, the project also discussed the need for alternative STB tolerance quantification methods, as well as the importance of environmental variations which have to be taken into account to study genetic variation in tolerance, but which could also be used to discriminate tolerant environment
Denoyes-Rothan, Béatrice. "Etude des relations hôte-pathogène chez le couple Fragaria x ananassa et Colletotrichum spp". Bordeaux 2, 1997. http://www.theses.fr/1997BOR28496.
Selmi, Hela. "Effet de l'ajout de biochar sur la symbiose tripartite Ensifer meliloti-Rhizophagus irregularis-luzerne (Medicago sativa L.), sur la production d'inocula bactériens et envers la lutte aux agents pathogènes". Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/26598.
Sustainable agriculture is based on the use of less chemical inputs and promotes the use of biological products such as biochar. Many studies clearly indicate that some biochars can stimulate biological nitrogen fixation in legumes. Our project aims to study the effect of a biochar (Pines, 700ºC) on the tripartite symbiosis Ensifer meliloti-Rhizophagus irregularis-Medicago sativa L., on the production of bacterial inocula and on the fight against pathogens. A culture of alfalfa inoculated with two strains of E. meliloti A2 or S14, in the presence of Rhizophagus irregularis and in a soil amended with 0, 15 or 30% of biochar (vol:vol) was conducted. A significant stimulation of mycorrhization was observed in the presence of 15% biochar and A2 or S14. However, inoculation of alfalfa with A2 or S14 had no significant effect on yields, indicating the presence in soil of effective strains of E. meliloti. A study on survival of rhizobia and Bacillus subtilis MBI 600 at 4°C and 25°C was conducted for 120 days. It showed that biochar (15%, vol:vol) promotes significantly the survival of rhizobial cells but for Bacillus subtilis it is the Pro-mix without biochar which supports better cell survival. Thus, the biochar effect on survival of microorganisms depends on the dose of biochar used. The effect of biochar amendments on P. ultimum and FORL colonization and infection was also evaluated. The study of the effect of three doses of biochar (0, 15, 30%; vol:vol) on pathogens showed that high doses may offer a good environment for pathogens development. Our study was performed using a single type of biochar with three doses. Therefore, it is very important to test other types and doses of biochar to be able to make recommendations.
Wen, Guoqi. "Étude des effets de la fertilisation azotée sur les concentrations foliaires en sucres, en acides aminés et en glycoalcaloïdes des plants de pommes de terre". Doctoral thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/66330.
Battiston, Enrico. "Développement d’un outil innovant pour optimiser l'activité biologique des substances actives afin de contrôler des maladies fongiques chez Vitis vinifera L. Unmanned A erial Vehicle (UAV) - based remote sensing to monitor grapevine leaf stripe disease within a vineyard aff ected by esca complex Grapevine trunk diseases: a review of fifteen years of trials for their control with chemicals and biocontrol agents". Thesis, Reims, 2018. http://www.theses.fr/2018REIMS046.
The research investigates the application of biomimetic calcium phosphate as innovative delivery system for grapevine (Vitis vinifera L.) protection purposes. This smart material was successfully studied in the biomedical field, from the functionalization of biomimetic calcium phosphate with anti-cancer molecules for localized releases, to the development of an innovative toothpaste for oral hygiene. Preliminary assays to implement the control of the grapevine fungal diseases, have revealed promising results. In this framework, the biomimetic inorganic hydroxyapatite was investigated as potential delivery system of bioactive substances allowed in organic agriculture for plant protection.Through a multidisciplinary approach, the study was aimed to evaluate the efficiency of hydroxyapatite in enhancing the biological activity of copper(II) compounds, on the control of relevant common diseases, like downy mildew, and complex fungal diseases, such as the grapevine trunk diseases. This aim is related to further ambitious goals: the significant reduction of the fungicides amounts applied in plant protection and the optimization of the distribution and persistence of the bioactive substances in the plant tissues, including the vascular ones, where harmful pathogens can develop. Overall, the experimental activities allowed: (i) to understand the interaction between delivery system, functional substance and grapevine tissues; (ii) to demonstrate the mechanism on which the higher efficacy of the functional substance is based; (iii) to collect new information on the mechanisms involved in the symptoms expression by studying the plant defense reactions induced by the treatments
Loqman, Souad. "La lutte biologique contre la pourriture grise de la vigne: Isolement, caractérisation de souches de bactéries Actinomycétales antagonistes à partir des sols rhizosphériques de vignes saines sauvages d'origine marocaine". Reims, 2009. http://theses.univ-reims.fr/sciences/2009REIMS037.pdf.
The aim of this study was to isolate PGPR Actinomycetes from wild healthy Vitis vinifera rhizosphere soil collected from several Moroccan regions in order to control Vitis vinifera grey mold agent Botrytis cinerea (Bc). In the course of our screening program for (Bc) antagonistic actinomycetes, we selected 142 isolates from 4 different Moroccan regions (Errachidia, Skoura, Tinjdad, Tinghir). Twenty four isolates were selected for their antifungal activity against Botrytis cinerea. Nine active isolates showing wide activity spectrum were screened for several PGPR capabilities. All 9 active isolates grow on Vitis vinifera root exudates. However, five only showed the antagonistic effect on this medium. They also produce the phytohormone-like compound of the IAA family, chitinases and siderophores making them very promising for plant growth stimulation (PGPB activity). The most powerful strains were then characterized on some physiological aspect (endophytic property, mineral phosphate solubilisation). The sequencing of the ARN 16S of these strains revealed that they are likely belonging to the genus Streptomyces. In the second part of this work, the fine taxonomic status of SS38, SS40 and SS10 strains was established using a polyphasic approach. Phylogenetic analysis based on the almost complete 16S rRNA gene sequence indicated that strain SS10 belongs to the Group I streptomycetes, branching off next to Streptomyces marokkonensis DSM 41918T from the Streptomyces violaceoruber group. DNA-DNA relatedness and phenotypic data distinguished strain SS10T from the phylogenetically closest related type strains. It is therefore proposed that strain SS10T (CCMM b35 T = DSM 41919T) represents the type strain of a novel Streptomyces species, for which the species name Streptomyces thinghirensis is proposed. SS38 strain is retained for the following investigations: extraction, purification and chemical structures identification of its produced compounds. .