Дисертації з теми "Résistance aux maladies – Génétique"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Résistance aux maladies – Génétique".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Palloix, Alain. "Potentiel et limites d'une résistance polygénique : la résistance du piment (Capsicum annuum) à Phytophthora capsici." Lyon 1, 1986. http://www.theses.fr/1986LYO10094.
Darvishzadeh, Reza. "Déterminisme génétique de la résistance du tournesol au Phoma." Phd thesis, Toulouse, INPT, 2007. http://oatao.univ-toulouse.fr/7587/1/darvishzadeh.pdf.
Chazara, Trokiner Olympe. "Diversité génétique structurale et fonctionnelle du CMH chez le Poulet : Implication pour la résistance aux maladies." Phd thesis, AgroParisTech, 2010. http://pastel.archives-ouvertes.fr/pastel-00601989.
Chazara, Olympe. "Diversité génétique structurale et fonctionnelle du CMH chez le Poulet : implication pour la résistance aux maladies." AgroParisTech, 2010. https://pastel.hal.science/index.php?halsid=35l606vho81sjdsfhrtdi0bke1&view_this_doc=pastel-00601989&version=1.
The major histocompatibility complex (MHC) is a complex genomic region in Vertebrates, still imperfectly known in the chicken and which shows a great genetic variability. The MHC is also an interesting region for studying the genetic determinism of adaptation to pathogens in an evolutionary context. Moreover, the MHC plays a central role in the immune response of an animal to infectious diseases, while a better understanding of the genetic determinism of the immune response against pathogens is important for developing a comprehensive strategy to fight against infectious diseases. We therefore used recent tools of genomics, including genetic markers such as SNPs (Single Nucleotide Polymorphism) to characterize the B region of the chicken MHC. First, genetic diversity has been evaluated in more than 80 breeds or populations with the LEI0258 marker. Then, to cover the entire region using SNP markers, we chose to identify these polymorphisms by resequencing 11 genes of interest and comparing the sequences obtained with the genome sequence and reference sequences available in databases. It also led to the improvement of the knowledge of a number of genes, including three DM-like non-classical class II genes. A 96 SNPs chip, dedicated to the B region of the chicken MHC, has been produced and will soon provide the genotypes of a number of infectious challenge studies conducted at INRA
Texereau, Joëlle. "Variabilités génétiques de l'immunité innée pulmonaire dans le risque infectieux : application à la mucoviscidose." Paris 12, 2006. http://www.theses.fr/2006PA120013.
Cystic fibrosis is a frequent life-threatening disorder. Despite identification of the genetic defect, disease physiopathology remains unclear, especially for pulmonary involvement that conditions prognosis. Role of genetic background is suspected. Potential influence of genetic polymorphysms in nitric oxide (NO) pathway and pathogen recognition Toll-like receptors (TLRs) was studied. A repeat polymorphism within the regulatory region of the NOS1 gene was associated with high airway NO production and better lung function in adults with CF. High exhaled NO was linked to preserved transepithelial ion transport. Absence of TLR2 and TLR4 impaired antibacterial roles of alveolar macrophage. The tlr2-753R[to]Q variant allele, which results in aloss of cellular response to CF pathogens, conferred to carriers a fourfold risk of airway infection. By contrast, tlr4-299D[to]G polymorphism, which lowers inflammatory response, was associated with a better lung function and prognosis
Protopapadakis, Eftichios. "L'électrophorèse appliquée, outil pour la sélection, la génétique et la physiologie des agrumes." Paris 11, 1988. http://www.theses.fr/1988PA112360.
Fleury-Hervé, Delphine. "Déterminisme génétique d'une résistance du tournesol à Sclerotinia sclerotiorum : Recherche de paramètres physiologiques précoces." Toulouse, INPT, 2001. http://www.theses.fr/2001INPT015A.
Ferrero, Frédéric. "Approche physio-pathologique et exploitation génétique de l'expression de la résistance à l'oïdium (sphaerotheca pannosa lev. , var. Rosae) dans le genre Rosa." Avignon, 2005. http://www.theses.fr/2005AVIG0314.
Powdery mildew of the rose tree induces heavy economic consequences. This disease is due to an external fungus Sphaerotheca pannosa var. Rosae that develops on the host without resulting in his death. This work of thesis points out a study in four steps of the relations host-parasite : 1- the evaluation of the expression of the symptoms of powdery mildew, in two collections, one of botanical species and another of modern rose trees. This approach allowed to identify resistant genotypes. 2- a program of crossings to evaluate the transmission of resistance and abilities for combination. The observation of the segregations, on the progenies from a diallele crossing plan between diploid species, confirmed that the character of resistance was controlled by several genes. The process for introgression of resistance, via a dihaploïd (2x) of modern rose tree (4x) cross with R. Wichuraïana (2x) followed with serial brother-sister crossings revealed as essential to fix the character. 3- the search for tools of sifting. This one led to a biological test of evaluation of resistance to powdery mildew and to methods for the isolation of the inoculum and following for the obtainment of mono-conidial isolates. 4- the study of the installation of the foliar cuticle and its efficiency according to : genotype, age of the organ and environmental conditions. A process was established to modulate the installation of the cuticle on plantlets resulting from in vitro. The cuticular evapotranspiration of resistant genotypes was measured lower than that of sensitive. At last, high calcium level in the nutrition of rose tree would activate the biosynthesis of the cuticle. In conclusion, the whole of these results contributes to the knowledge of the disease and to the definition of a strategy for the selection of the character of Resistance to powdery mildew
Di, Filippo Sylvie. "Facteurs immuno-génétiques impliqués dans le devenir du greffon et du patient après transplantation cardiaque pédiatrique." Lyon 1, 2005. http://www.theses.fr/2005LYO10017.
Thabuis, Arnaud. "Construction de résistance polygénique assistée par marqueurs : application à la résistance quantitative du piment (Capsicum annuum L.) à phytophthora capsici." Paris, Institut national d'agronomie de Paris Grignon, 2002. http://www.theses.fr/2002INAP0045.
Phytophthora capsici causes important losses on pepper crop. Resistant accessions were found among the intraspecific germplasm but all displayed a partial resistance level. The goals were to analyse the genetic determinism of these qualitative resistance, to set up a marker-assisted selection (MAS) strategy and to analyse its efficiency. Three intraspecific genetic maps were elaborated. Their aligment enabled to compare the localisation of resistance factors. This study showed that the major resistance factor was common to the 3 accessions, others were specific of a resistant accession. A MAS program was set up to transfer the resistance factors into bell pepper genetic background. After 3 cycles of marker-assisted backcross selection, the effects of the introgressed resistance factors were validated. A decrease of the resistance factor effect was detected in validation populations. This strategy enabled an efficient return to the recipient parent. The comparison of the MAS strategy with phenotypic selection currently used by pepper breeders showed that the resistance level selected was the same and that a more important horticultural improvement occured using MAS strategy
Flori, Laurence. "A la recherche des gènes contrôlant la résistance humaine au paludisme à P. Falciparum : apport des analyses de liaison génétique et d'association allélique avec la parasitémie et le risque d'accès palustre." Aix-Marseille 2, 2004. http://www.theses.fr/2004AIX22037.
Meaux, Juliette de. "Polymorphisme moléculaire relatif à la résistance aux maladies dans les populations naturelles de haricot commun (Phaseolus vulgaris)." Paris 11, 2002. http://www.theses.fr/2002PA112001.
Molecular analysis of diversity at complex resistance gene loci suggest that selection could have contributed to their organisation. In common bean (Phaseolus vulgaris) two multigenic families of Resistance Gene Candidates (RGCs) have been identified, among which one shows a greater complexity with more numerous members than the other. In an attempt to bring insight into the question of the evolutionary forces which may have shaped their evolution, RFLP polymorphism for these 2 gene families was assessed in wild populations sampled across several regions. The populations had been previously assessed for diversity at neutral loci (RAPD) and diversity for resistance phenotypes to strains of Colletotrichum lindemuthianum, one of the major pathogen of bean. RGC polymorphism was detected for both gene families both within and among populations, at all geographical scales. The analysis of diversity shown by the less complex of the two families indicates that copy number polymorphism may be found at all geographical scales. .
Foulon, Eliane. "Rôle des cellules dendritiques dans la variabilité génétique de la résistance aux infections mammaires chez la brebis." Toulouse 3, 2007. http://www.theses.fr/2007TOU30098.
A divergent selection in dairy sheep has been settled to evaluate its effect on resistance to mastitis. Mammary immunity was examined after natural or experimental infections with Staphylococcus. Mastitis were more severe in ewes from the susceptible group, and led to abscesses formation. In order to elucidate the mechanisms associated with the cure of infection, we hypothesized that dendritic cells, that are known to play a crucial role in anti-infectious immunity against bacteria, could be responsible for the observed differences. We designed a protocol to differentiate dendritic cells from bone marrow precursors. Microarray analysis of gene expression was performed on dendritic cells that had been stimulated with Staphylococcus aureus. Using this approach 3 genes that have up-regulated in ewes from resistant group have been identified
Rutschmann, Sophie. "La Réponse immunitaire humorale de la drosophile : Analyse génétique par mutagenèse systématique à l'EMS." Université Louis Pasteur (Strasbourg) (1971-2008), 2002. http://www.theses.fr/2002STR13042.
Insects are able to mount an efficient host defense to fight against microbial infections. A hallmark of their immune response is the synthesis and release in the hemolymph of a cocktail of antimicrobial peptides. Genetic studies have shown that, in Drosophila, at least two independent pathways control the expression of antimicrobial peptides : the Toll pathway, that regulates the antifungal response, and the imd pathway, that is responsible for the antibacterial response. Nevertheless, some aspects of the regulation of the immune response remained to be elucidated : what are the mechanisms that allow self versus self-non self recognition? What are the components of the activating cascades through hemolymph that signal the presence of pathogens? Which are the members of the imd and Toll pathways that are still unknown? To address these questions, the team in which I accomplished my Ph. D. Thesis realized an EMS (Ethyl Methan Sulfonate) mutagenesis screen of the second chromosome of Drosophila. The aim of this approach is to identify all the genes involved in the regulation of the antimicrobial peptide genes expression. During the mutagenesis screen, we performed more than 27000 crosses and established 7600 fly strains homozygote for mutations carried by the second chromosome. Screening these mutants allowed us to recover several Drosophila lines affected either in the antifungal or the antibacterial response. Analysis of these mutants suggest that the two distinct pathways controlling Drosophila immune response result in the activation of two different Rel proteins : Dif (antifungal pathway) and Relish (antibacterial pathway). The cloning of the genes identified during the screen allowed us to show that the two pathways mediating antimicrobial immune response in Drosophila are largely independant
Lebreton, Amandine. "Évaluation de la résistance de cultivars de soya à plusieurs races de Phytophthora sojae." Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26201.
El, Attari Hania. "Etude et amélioration de la résistance génétique du blé et de l'orge à la strie bactérienne causée par Xanthomonas campestris pv. Cerealis et pv. Hordei." Toulouse, INPT, 1997. http://www.theses.fr/1997INPT006A.
Laquitaine, Laurent. "Etude de la régulation et du rôle physiologique du gène Ub-LTP1 (Ugni blanc Lipid Transfer Protein 1) : analyse fonctionnelle du promoteur et mise en évidence de facteurs inducteurs." Poitiers, 2004. http://www.theses.fr/2004POIT2356.
Nyassé, Salomon. "Etude de la diversité de Phytophthora megakarya et caractérisation de la résistance du cacaoyer (Theobroma cacao L. ) à cet agent pathogène." Toulouse, INPT, 1997. http://www.theses.fr/1997INPT012A.
Iquira, Elmer. "Caractérisation de ressources génétiques conférant une résistance partielle à la sclérotiniose chez le soja." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30219/30219.pdf.
White mold is an important disease of soybean in North America. Genetic resistance to this disease is a cost-effective way to control this disease. In order to better understand the genetic control of resistance, we first developed two research tools: i) a method to characterize soybean lines in terms of their resistance to white mold; and ii) a genotyping approach for obtaining information on hundreds or thousands of markers simultaneously. In a second phase, we used these new tools to identify the genomic regions responsible for resistance to white mold via two approaches: i) a "traditional" biparental QTL mapping approach and ii) an association mapping approach. At first, we developed and validated a reliable and reproducible method for artificial inoculation to measure resistance to white mold. Then, we developed a genotyping by sequencing (GBS) approach to quickly and efficiently characterize a large number of SNP markers in soybean. As part of this work, a protocol for preparing GBS genomic libraries has been developed as well as a pipeline of bioinformatics analysis to call SNPs. Finally, genetic mapping analysis was performed on two populations to identify genomic regions conferring resistance to white mold. In the first case, a population of 141 F6 lines from a cross between the cultivars Majesta and Hikmok Sorip was characterized for resistance to the disease. By using a dense genetic map counting 515 SNP markers obtained by GBS, we have identified a region on chromosome Gm07 contributing to the resistance observed in the cultivar Majesta. In the second case, 101 unrelated soybean lines were characterized for their resistance to disease and were genotyped with 8,397 SNP markers obtained by GBS. The mapping association analysis identified three chromosomal regions strongly associated with disease resistance. The strongest association was found on chromosome Gm03, while regions on chromosomes Gm08 and Gm20 also showed significant associations. These results will facilitate the identification of exotic lines in which resistance is likely based on different genes to be introduced in the Canadian germplasm.
Boudhrioua, Chiheb. "Étude de la résistance à la pourriture à sclérotes chez le soja canadien." Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/35781.
Sclerotinia stem rot (SSR) (Sclerotinia sclerotiorum) is one of the most important soybean diseases causing considerable damage in Canada in the absence of fully resistant lines. Thanks to genomic selection, it is possible to develop lines with increased resistance to this ascomycota. But first, it is necessary to identify the genomic regions responsible for resistance, to guide breeders' choices regarding parents to be used for crosses, as well as to inform selection with the help of molecular markers. In this study, we conducted a genome-wide association study (GWAS) to identify quantitative trait loci (QTL) of partial resistance in Canadian material. We genotyped 127 lines, previously evaluated for SSR resistance, with close to 1.5M high-quality SNPs. This catalog offers extensive genome coverage and the opportunity to explore areas that were incompletely covered in previous studies. This analysis identified a new QTL on chromosome 1 Gm 01 where the resistant allele reduced lesion length on the stem by 29 mm. To validate this QTL, the descendants of a cross between two lines carrying contrasted alleles for Gm01 were genotyped and then evaluated for resistance. The results show that individuals carrying the resistance allele developed lesions that were 43 mm shorter, a reduction of 48% compared to those bearing the sensitivity allele. These results suggest that this QTL is a promising candidate for developing soybean lines with enhanced resistance to SSR.
Ngondjo, Georges. "Effet d'un apport de silice sur la diminution de la sensibilité du riz à l'infestation par les foreurs des tiges : Chilo zacconius Bleszynski et Sesamia calamistis Hampson." Montpellier 2, 1986. http://www.theses.fr/1986MON20078.
Cavaillès, Pierre. "Etude du contrôle génétique de l'atopie et de la résistance à la toxoplasmose, à l'aide de lignées congéniques réciproques de rats BN et LEW." Toulouse 3, 2005. http://www.theses.fr/2005TOU30149.
Sergent, Véronique. "Le rat LEW, un modèle d'étude de la résistance à l'infection toxoplasmique : analyses génétiques et immunologiques." Lille 2, 2002. http://www.theses.fr/2002LIL2MT23.
Bastien, Maxime. "Étude de la résistance à la sclérotiniose chez le soya." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30341/30341.pdf.
Sclerotinia stem rot (SSR), caused by the fungus Sclerotinia sclerotiorum, is one of the most important soybean diseases in Eastern Canada. Using resistant varieties is the most efficient and economic way to repress this disease. However disease pressure in the field fluctuates considerably from year to year according to climatic conditions, thus impeding the identification of resistant material. We developed a reliable and reproducible artificial inoculation method to assess resistance in the greenhouse and in the field. Named the «cotton pad method», it relies upon applying a piece of cotton pad soaked in a mycelial suspension on a floral bud and to measure the ensuing lesion length one week after inoculation. This quick and easy method provides disease ratings similar to the reference method used in Québec and is able to distinguish true resistance from disease avoidance mechanisms. We then used the cotton pad method to evaluate the degree of resistance in a panel of 130 soybean lines representing the genetic diversity present in this species in Quebec. In parallel, we developed a high-throughput genotyping by sequencing method for soybean and used it to genotype the collection. Sequencing provided 266.7 million distinct sequences, which yielded 7,864 SNPs on the 20 soybean chromosomes after several filtering steps. Association mapping performed between the genotype of the lines and their resistance level revealed the presence of four quantitative trait loci (QTLs) associated with SSR resistance. The strongest association was validated in a biparental population generated from a cross between two parents contrasted at this locus. Furthermore, none of the most resistant lines developed so far carries all of the resistance alleles, which suggests that it is possible to develop lines presenting increased SSR resistance. These results are promising for marker assisted or genomic selection.
Musoli, Pascal. "Recherche de sources de résistance à la trachéomycose du caféier Coffea canephora Pierre, due à Fusarium xylarioides Steyaert en Ouganda." Montpellier, ENSA, 2007. http://www.theses.fr/2007ENSA0010.
Barsalobres, Cavallari Carla Fernanda. "Identificação e caracterização de promotores de genes de café (Coffea arabica)." Montpellier 2, 2009. http://www.theses.fr/2009MON20223.
The choice of promoter, to confer constitutive, spatial and/or temporal transgene expression, is one input in plant biotechnology applications. This study presents the identification and characterization of different gene promoters in coffee (Coffea arabica), a species of major socio-economic characteristics. Forty one constitutive, fruit-specific or pathogen defense-related genes were identified following literature data or in silico analyses in available EST databases. The expression levels of these genes were verified by quantitative PCR and merely 10 genes presented a real constitutive or specific expression condition. The expression levels assays were carried out in 5 coffee organs/tissues (root, stem, leaves, flowers and fruits) or in coffee plants challenged with Hemileia vastatrix. The promoter region of 4 genes were isolated and characterized in silico: CaGAPDH (inner control), CaAN2 (anthocyanin2 fruit-specific), CaPR1b and CaNPR1 (basic form of pathogenesis-related protein1 and nonexpressor of PR genes, both pathogen-inducible). The functional analyses of the DNA sequence upstream of these genes were assessed with regard to the iudA reporter gene, via Agrobacterium-mediated transient expression assay in tobacco or tomato plants. The characterization of promoters is not only an approach towards coffee breeding programs, but also provides fundamental data for understanding the mechanisms regulating gene expression in perennial plants
Bardin, Marc. "Diversité phénotypique et génétique des oïdiums des cucurbitacées, Sphaerotheca fuliginea et Erysiphe cichoracearum." Lyon 1, 1996. http://www.theses.fr/1996LYO10103.
Bakkali, Nawal. "Mécanismes moléculaires de résistance au sulfaméthoxazole chez Tropheryma whipplei, l'agent de la maladie de Whipple." Aix-Marseille 2, 2009. http://www.theses.fr/2009AIX20718.
Obligate intracellular bacteria, by their intracellular location, are difficult to neutralize by antibiotics. In a first part, we present a review of molecular mechanisms of resistance to antibiotics and attempts at genetic manipulation of intracellular bacteria. Our work has focused on one of them: Tropheryma whipplei, the agent of Whipple's disease. The recommended empirical treatment for this disease involves the simultaneous administration of sulfamethoxazole and trimethoprim (cotrimoxazole). A recent work in our laboratory has demonstrated the ineffectiveness of trimethoprim in vitro because of the absence of its target gene, folA coding for DHFR in the genome of the bacterium. Cases of treatment failures with this treatment and relapses were also reported in the literature suggesting the possibility of acquiring resistance to sulfamethoxazole during treatment. The 1st objective of this thesis was to study the molecular mechanism of antibiotic resistance of T. Whipplei to sulfamethoxazole. The sequence of folP the encoding gene of sulfamethoxazole’s target: the dihydropteroate synthase (DHPS) was obtained from clinical isolates of T. Whipplei and also from positive samples from a patient with treatment failure before and after starting treatment. The sequences obtained from this patient showed several mutations compared to sequences obtained from other strains of T. Whipplei. Gene analysis showed that folP was identified among genes encoding a unique trifunctional enzyme in which DHPS is combined with the 2 preceding enzymes of the folate biosynthesis pathway. Sequencing showed multiple mutations in folP gene in the patient case. Complementation of an Escherichia coli strain knockout for folP with sequence associated with treatment failure has not only restored the folate biosynthesis pathway but also induced resistance to sulfamethoxazole compared with the wild sequence. We also demonstrated for the first time that the mutated sequence of this gene has led to a different protein sequence and induced resistance in vitro to sulfamethoxazole and could explain the failures and relapses observed during the treatment of this disease. The second part of this thesis has focused on assessing the susceptibility of T. Whipplei in vitro to another sulfonamide: the sulfadiazine. Given the results obtained and the pharmacological properties of this compound, we propose its use as an alternative to the cotrimoxazole in combination with doxycycline and hydroxychloroquine in neurological involvement
De, la Chevrotière Claudia. "Analyse de la variabilité génétique de la résistance aux strongles gastro-intestinaux chez les chèvres créoles à des fins de sélection et de compréhension des mécanismes." Thesis, Antilles-Guyane, 2011. http://www.theses.fr/2011AGUY0407/document.
The two main objectives of this work are to propose tools for the selection of resistant animals to gastrointestinal nematodes and advance knowledge on mechanisms of resistance of creole goats. this work has analysed the genetic variability of resistance to digestive parasitism in order to determine which criteria best describes the resistance and can be use for selection. the overall results suggest that the egg excretion and the eosinophilia are the criteria most suitable for a breeding scheme because they have moderate heritability estimates and best represent the resistance. moreover, they do not seem in conflict with the weight, the main criterion of production. the genetic determinism of resistance to gastrointestinal parasites has been studied and has highlighted the existence of a major gene for resistance in creole goats. in addition, the primodetection of qtl identified 13 genomic regions that affect the resistance. the mechanisms behind the resistance to gastrointestinal parasites were also studied and first hypothesis regarding the involvment of the immune response in resistance have been made in goats. the overall results highlighted the role of eosinophils in the development of resistance to gastrointestinal nematodes. the activity of immunoglobulin e seems directed toward l3 larvae of haemonchus contortus and may be imply in the establishment of a protective response agasint nematode parasites. in creole goats, these two mechanisms seem to play an important role in the development of resistance to gastrointestinal nematode infections
Leforestier, Diane. "Localisation de régions du génome du pommier contrôlant la variation de caractères de qualité du fruit et de résistance aux maladies : signatures de sélection et génétique d'association." Thesis, Angers, 2015. http://www.theses.fr/2015ANGE0051/document.
Since apple domestication, humans have progressively selected improved varieties, especially for traits linked with fruit quality, productivity or resistance to pathogens. The genetic bases underlying these traits have been explored thanks to genetic mapping in F1 segregating populations that only allows the study of a small part of the available genetic diversity. The aim of this work was to analyze the genetic bases of fruit quality and disease resistance against apple scab and fire blight, in collections of old apple varieties representing a much larger diversity. Genotyping of core collections was performed either with arrays of 8k and 480k SNPs or by resequencing of chosen genes. Signs of genetic differentiation were identified between cider and dessert apples and were partially linked to the polyphenols pathway. After studying linkage disequilibrium, both on a large and a small scale, an association genetics approach allowed the identification of genomic regions associated with the variation of several fruit quality traits. Especially, the top of linkage group 16 was found to be linked with acidity (locus Ma), firmness, juiciness and bitterness (LAR gene). Concerning the resistance of apple to fire blight, a region containing a homolog of the NPR1 gene (defense activator) was identified. This thesis allowed the refining of the putative localization of previously identified QTLs and the identification of new genetic resources that could be useful in future selection programs using marker assisted selection
Zablocki, Laurent. "Identification de facteurs de régulation de la voie de signalisation TLR3 par crible génétique." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS533.
The fight of the organism against pathogens involves the detection of molecular patterns that are conserved among pathogens. Among the arsenal of receptors capable of recognizing these patterns, there is the family of endosomal Toll-like receptors (TLRs) that are specific for nucleic acids. Among them, TLR3 senses the abnormal presence of double-stranded RNA in the endosomes and initiates a potent innate immune response. Nevertheless, mechanisms governing TLR3 regulation still remain poorly understood. To identify new molecular players involved in the TLR3 pathway, we performed a genome-wide screen using the CRISPR/Cas9 technology using reporter cells expressing GFP when stimulated via TLR3. Mutagenesis was achieved by transducing these cells with the lentiviral GeCKO v2 sgRNA library. Cells were then subjected to sequential rounds of stimulation with poly(I:C) and sorting of the GFP- cells. Enrichments in sgRNA estimated by deep-sequencing identified genes required for TLR3-induced activation of NF-κB. Five genes, including TLR3 itself and the chaperone UNC93B1, known to be critically involved in the TLR3 pathway, were identified by the screen, thus validating our strategy. We further studied the best 40 hits. Among the hits confirmed, we focused on AhR (aryl hydrocarbon receptor). Depletion of AhR had a dual effect on the TLR3 response, abrogating the IL-8 production and enhancing the IP-10 release. Interestingly, in primary human macrophages exposed to poly(I:C), AhR activation enhanced IL-8 and inhibited the IP-10 one. Overall, AhR appears able to modulate the TLR3 response
Guérin, Fabien. "Mise en évidence d'une population génétiquement différenciée de Venturia inaequalis, agent de la tavelure du Pommier, associée au contournement du gène majeur de résistance Vf." Angers, 2004. http://www.theses.fr/2004ANGE0021.
Strategies of genetic control against the phytopathogenic fungus Venturia inaequalis are mainly based on the use of major resistance genes which confer a complete resistance towards the disease. By the end of the Eighties, strains virulent against Vf, the most used resistance gene were evidenced. This thesis was aimed at understanding the evolutionary dynamics of pathogenic populations confronted to selection pressures exerted by a major gene of resistance. Thanks to the use of molecular markers, such as microsatellites and AFLP, we followed up the genetic structure of V. Inaequalis populations in several locations over several years. Our results showed that the genetic diversity of virVf populations drastically decreased as compared to the avrVf populations, revealing the typical structure of a founder effect. In addition, we showed that virVf populations were strongly differentiated from the avrVf populations and that they were stochastically dispersed over Europe from a common source of virulence. Finally, we revealed the maintenance of the genetic differentiation in space and time between virVf and avrVf populations. The lack of gene flow between virVf and avrVf compartments indicated a reproductive isolation of virVf strains, which could be partly explained by the avirulence spectrum of these strains towards some of the non-Vf hosts in the studied orchards. Results obtained from this work allowed us to discuss on the origin and the dispersion of the Vf virulence and then to propose topics to investigate in order to preserve the efficiency of the Vf resistance gene
Blanchet, Charlène. "Identification de facteurs génétiques contrôlant la résistance de lignées de souris consanguines à une infection expérimentale par Yersinia pestis, l'agent de la peste." AgroParisTech, 2010. http://pastel.archives-ouvertes.fr/docs/00/60/68/35/PDF/These_Charlene_BLANCHET.pdf.
Plague is a zoonotic disease affecting mainly rodents and accidentally humans. The etiologic agent of bubonic and pneumonic plague is the Gram-negative bacterium Yersinia pestis. The mechanisms by which the host is able or not to resist the infection are poorly understood. We have shown that some mouse inbred strains, like C57BL/6J, die after the subcutaneous injection of 100 bacteria of a virulent strain (CO92), while others, like SEG/Pas, derived from Mus spretus, survive. A backcross between these two strains led to identification, on chromosomes 3, 4, and 6, of three QTL controlling survival rate. The first two were found only in females, while the chromosome 6 QTL was also found in males. Congenic mice carrying the SEG chromosome 6 in a C57BL/6J background were produced. After infection, they die in the same proportion as C57BL/6, but somewhat later. Bi- and tri-congenic strains are under production to assess the effect of other QTLs. We have tested a collection of 55 interspecific recombinant congenic strains between C57BL/6J and SEG/Pas. Several strains significantly differed from C57BL/6 in survival rate or time to death. The analysis of strain 120G, which dies earlier than C57BL/6J, suggests that the proximal region of chromosome 6 would be responsible for this phenotype. Altogether, our data show that genetic control of resistance to plague in SEG/Pas mice is complex, and we have identified several genomic regions which play an important role in this phenotype
Lakkis, Sara. "Résistance systémique induite par Pseudomonas fluorescens et Bacillus subtilis chez des génotypes de vigne de différentes sensibilités au mildiou et à la pourriture grise Strengthening Grapevine Resistance by Pseudomonas fluorescens PTA-CT2 Relies on Distinct Defense Pathways in Susceptible and Partially Resistant Genotypes to Downy Mildew and Gray Mold Diseases." Thesis, Reims, 2019. http://www.theses.fr/2019REIMS025.
Downy mildew caused by the oomycete Plasmopara viticola and grey mold caused by the fungus Botrytis cinerea are among the highly threatening diseases in vineyards. The current strategy to control these diseases relies totally on the use of chemical fungicides. The use of beneficial bacteria is arising as a sustainable strategy in controlling various diseases. This can be achieved through the activation of the plants own innate immune system, known as induced systemic resistance (ISR). Such a strategy is effective in controlling grey mold disease, but the efficiency against downy mildew is still in unknown, and the mechanisms underpinning the resistance state remain to be explored. In this study we focused on the capacity of Pseudomonas fluorescens PTA-CT2 to induce ISR in grapevine against P. viticola and B. cinerea by using two grafted cultivars differing in their susceptibility to downy mildew, Pinot noir as susceptible and Solaris as partially resistant. We then examined the differences and similarities of Bacillus subtilis- and P. fluorescens-mediated ISR and priming state after P. viticola challenge. On the basis of the contrasting phenotypic susceptibility of cultivars, we explored mechanisms underlying ISR before and upon pathogen infection. We provide evidence that P. fluorescens induces ISR against P. viticola and B. cinerea by priming common and distinct defensive pathways depending on the basal immunity of genotype. Although P. fluorescens elcits hormonal synthesis and photosynthetis efficiency before infection in both genotypes, our results highlight an important role for salicylic acid (SA)-dependent defense and phytoalexin synthesis, but not JA and ET signaling in ISR against P. viticola in both cultivars. The priming state relies further on the strong expression of HSR gene involved in HR-like cell death in Solaris, whereas in the susceptible cultivar it involves accumulation of ABA, rather than HR-like cell death. The induced ISR against B. cinerea is rather related to the activation of JA/ET signaling, but also to stilbene accumulation and reduction of cell death in both cultivars.The comparative approach between Bacillus subtilis- and P. fluorescens-ISR revealed significant differences in terms of primed defenses against P. viticola. Although both bacteria induce comparable level of ISR by mainly priming SA pathway and stilbene accumulation in both grape varieties, the strong responses are provided by B. subtilis which also induces high expression of the HR-related gene and the accumulation of SA, especially in the resistant hybrid variety. P. fluorescens potentiates to a lesser extent the expression of other SA-related genes and accumulation of ABA in both varieties. These results suggest that B. subtilis- and P. fluorescens-induced ISR against P. viticola could operate through common and distinct mechanisms depending on the basal resistance of grapevine genotype.Further transcriptomic analyses were performed on mock and P. fluorescens-treated Pinot noir after inoculation with B. cinerea and P. viticola, in order to characterize the expression of genes associated to ISR against pathogen with different lifestyle. A large number of differentially expressed genes (DEGs) identified from the RNA-seq data suggests that P. fluorescens-ISR could be associated with priming of several mechanisms depending on the pathogen lifestyle
Carmeille, Amandine. "Bases génétiques de la résistance de la tomate à Ralstonia solanacearum : comparaison des races 1 et 3." Phd thesis, Université de la Réunion, 2004. http://tel.archives-ouvertes.fr/tel-00546873.
Papapietro, Olivier. "Dissection génétique et études fonctionnelles du locus de contrôle de l'atopie Aiid3 et du locus contrôle de la toxoplasmose Toxo1, dans le modèle des rats BN et LEW." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/1037/.
Most human immune diseases are multifactorial, resulting from interactions between genetic and environmental factors. Their studies are hampered by genetic heterogeneity of human populations and by the variability of environment. In experimental conditions, using rodent models, environmental and genetic factors are under control. BN and LEW rats represent a powerful model to study immune-mediated diseases since they show strong differences in normal and pathological immune response. We used these strains to study genetic control of toxoplasmosis issue and mercury susceptibility. Linkage analyses in F2 (LEWxBN) rats followed by genetic dissection using reciprocal congenic and sub-congenic lines lead us to identified identified a major locus on chromosome 10 (c10) called Toxo1 in a 1. 09Mb region that direct toxoplasmosis outcome independently of the genetic background. Two major candidate genes have been identified and their implications in congenital toxoplasmosis outcome in human cohorts are under investigation. By a similar strategy, genetic control of heavy metal-mediated immune disorder has been investigated. In the BN rats, mercury salt induced IgE production, auto-antibodies-mediated nephritic syndrome and ANCA-associated vasculatis while the LEW rats are completely resistant to the disease induction. In this work, we show that the Aiid3 locus previously identified by our group control the set of the mercury-induced symptoms. Genetic dissection of the locus leads us to localize the gene(s) of control within a critical 117Kb region. 4 genes are present within this region and 2 are both polymorph and implicated in immune system homeostasis and function and appear as major candidate genes for the Aiid3-mediated biological effect
Fraslin, Clémence. "Bases génétiques de la réponse à l'infection par Flavobacterium psychrophilum chez la truite arc-en-ciel : approche expérimentale et perspectives en sélection." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLA038/document.
Health management and disease control are of both major economic and environmental concerns for animal production systems. Bacterial diseases are responsible for important economic losses in fish farming. Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD), affects particularly rainbow trout (Oncorhynchus mykiss) and is found worldwide where salmonids are raised. As no commercial vaccine is available at the moment, the only way to fight BCWD remains through the use of antibiotic treatments. In a context of growing antibiotic resistance threat, additional methods to tackle fish disease are highly needed. Improving the natural host defense mechanisms against infectious pathogens through selective breeding is one of the priorities for French trout farmers. Moderate heritabilities were estimated for resistance against BCWD, indicating that selective breeding is a promising approach to improve trout defense mechanisms against F. psychrophilum. In order to implement disease resistance in French breeding schemes, we need to better understand the genetic determinism of this trait.In this context, the objective of this PhD is to study genetic determinism of different components of trout response to different infection protocols with F. psychrophilum using a QTL (Quantitative Trait Loci) mapping approach.To do so we used three experimental crosses between isogenic lines of trout with contrasting susceptibility. Finally, a study on a commercial line under selection in a French breeding company was performed after a natural disease outbreak to validate the interest of QTL previously detected.In this study, we showed that an important number of interacting QTL controls rainbow trout response to infection with F. psychrophilum. Our results suggest that different components of response to infection (resistance, endurance, resilience, bacterial load) might be controlled by different genetic determinisms. We also showed that different infection protocols trigger different immune mechanisms that may be specific to the route of entry of the pathogen. This study paves the way toward a better understanding of underlying immune mechanisms of rainbow trout response to F. psychrophilum. Finally, this study is the first step toward implementing genomic selection of resistance to BCWD in French rainbow trout population
Salgon, Sylvia. "Déterminisme génétique de la résistance au flétrissement bactérien chez l'aubergine et applications en sélection variétale." Thesis, La Réunion, 2017. http://www.theses.fr/2017LARE0010/document.
Eggplant cultivation is confronted by the bacterial wilt disease caused by the Ralstonia solanacearum species complex. Breeding resistant cultivars is the most effective strategy to control the disease but is limited by the pathogen’s extensive genetic diversity. A major QTL (ERs1) was previously mapped in a recombinant inbred lines (RIL) population from the cross of susceptible (S) MM738 × resistant (R) AG91-25 lines. ERs1 was originally found to control 3 strains from phylotype I, while being ineffective against the strain PSS4 from the same phylotype. The objectives of this thesis was to (i) clarify the position of ERs1 and define its spectrum of action, (ii) found other QTLs, promptly to control virulent strains on AG91-25 and (iii) introgress some of the QTLs into two S cultivars. For this purpose, the new doubled haploid (DH) populations MM152 (R) × MM738 (S) and EG203 (R) × MM738 (S) were created. The RIL population was phenotyped with 4 additional RSSC strains belonging to phylotypes I, IIA, IIB and III and the DH populations were phenotyped with virulent strains PSS4 and R3598. QTL mapping confirmed the existence of ERs1 (renamed EBWR9), defined its position on chromosome (chr) 9 and validated its specific control of 3 phylotype I strains. EBWR2 and EBWR14, 2 broad-spectrum resistance QTLs, were detected on chr 2 and 5. QTL analysis reveals a polygenic system of resistance in EG203. The transfer of resistance into 2 local cultivars was initiated and allowed the introgression of EBWR9 and EBWR2 QTLs through a backcross scheme. These results offer perspectives to breed broad-spectrum R cultivars
Sanssené, Jean. "Nécroses racinaires du pois causées par Fusarium solani (Mart. ) Sacc. F. Sp. Pisi (Jones) Snyd. & Hans. (Nectria haematococca Berk. & Br. , Mating Population VI) : connaissance de la maladie et diversité de la population pathogène." Littoral, 2002. http://www.theses.fr/2002DUNK0092.
Fusarium solani f. Sp. Pisi is the most frequent root rot pathogen of peas in France. Before starting a breeding program of resistant varieties, investigation was carried out in two areas. The first one concerns the global study of the disease, with experiments conducted in the field and in semi-sterile conditions in the laboratory. The pathogen affects the plant when the temperature exceeds 8°C, even more in dry conditions. The necrosis is generally centred around the zone of insertion of cotyledons. On the other hand, in dry conditions, it extends superficially over the whole length of the root, while the seed and the epicotyl remain healthy. The plant growth is reduced when the fungus reaches the central cylinder, and induces the degradation of the cambium and the phloem, then prevents the extension of the xylem. The seriousness of the attack is well represented by the notation of rotted section. Secondly, we study the diversity of the French population of solani f. Sp. Pisi, from a collection of hundred monosopore isolates. The sequences and the PCR-RFLP analyses of the ITSs, and of the 28S rDNA, confirm the membership in the mating population MPVI. In this population, different clones were identified by combining the analysis of the esterases and the telomeric extremity. Some of them present common morphological characters useful for their identification. Within a clone, the pathogenicity varies strongly between isolates. Thirty genotypes of pea showed differences of resistance to various clones. As a consequence, the choice of the most frequent clone in France is imperative for the future breeding of resistant pea varieties. This work opens up perspectives of study of the constituents of pathogenicity of F. Solani f. Sp. Pisi, as well as constituents of pea resistance to this pathogen
Mokrani, Loubna. "Cartographie du tournesol, détection de QTLs de quelques Caractères d'intérêt et sélection assistée par marqueurs : exemple de l'acide oléïque." Toulouse, INPT, 2002. http://www.theses.fr/2002INPT014A.
Subba, Rao P. Venkata. "La Rouille de l'arachide : étude de quelques mécanismes de défense de l'hôte." Paris 11, 1987. http://www.theses.fr/1987PA112395.
Puccinia arachidis Speg. , causal agent of rust disease of groundnut (Arachis hypogaea L. ), is a major foliar pathogen in most of the groundnut producing areas in the world. Studies have been made of groundnut-rust interactions and their modulation by means of chemical or biological agents. The results obtained indicate that at the cellular level the mechanisms of resistance do not involve cell-wall reinforcement, white at molecular level, infection stimulates peroxidase activity only to modest levels. Quantitative differences observed among various génotypes (cultivated) in their protein and total phenolic contents do not seem to correlate with their resistance levels; however their total phenolic content was far less than that of the wild species (highly resistant or immune). Groundnut plants produce at least ten antifungal compounds in response to infection; these include unsaturated fatty acids, their oxygenated derivatives, an aliphatic compound, nonyl phenols, alkyl bis phenylethers, hydroxystilbenes and pterocarpans (medicarpin). The chemical structure of most of these compounds has been determined. These compounds seem to be preformed in resistant genotypes and their biosynthesis is stimulated by infection. Such a stimulatory response does exist in susceptible genotypes, but is of smaller amplitude and is usually delayed. Leaf detachment and its survival away from the plant favour accumulation of antifungal compounds. Nevertheless, such a response does not seem to contribute towards an increase in resistance levels, suggesting the involvement of other factors in the resistance mechanisms against P. Araclùdis. Lt was found that the defence reactions of the groundnut plant could be modulated either by the application of chemical compounds (Fosetyl-AI) or by cross-protection techniques. Such treatments showed an effect on some components of resistance leading to significant reductions in build-up of epidemies. The investigation of such modulations would contribute to the elucidation of physiological and biochemical mechanisms involved in host resistance
Chalhoub, Boulos. "Le sérotype PAV du virus de la jaunisse nanisante de l'orge (BYDV-PAV) : interaction d'isolats du BYDV-PAV avec l'orge cultivée (Hordeum vulgare L) : contrôle génétique de la résistance partielle des génotypes d'orge : polymorphisme de la région 3'-Terminale du génome viral." Toulouse, INPT, 1994. http://www.theses.fr/1994INPT014A.
Rachid, Alchaarani Ghias. "Variabilité génétique et identification des QTLs liés à la qualité des semences chez le tournesol (Helianthus annuus L. )." Toulouse, INPT, 2004. http://www.theses.fr/2004INPT002A.
Djebali, Naceur. "Etude des mécanismes de résistance de la plante modèle Medicago truncatula vis-à-vis de deux agents pathogènes majeurs des légumineuses cultivées : Phoma medicaginis et Aphanomyces euteiches." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/581/.
To gain insights into resistance mechanisms in legumes against fungal-like microorganisms, two pathosystems were developed with the model legume Medicago truncatula (Mt) on one side, P. Medicaginis (Pm), responsible for black stem alfalfa disease and A. Euteiches (Ae), the causal agent of pea root rot disease, on the other side. Several fungal isolates were collected across Tunisia and thereafter identified. One Pm isolate, selected for its high aggressiveness, was inoculated on two Mt lines that displayed contrasted responses to Pm. Analysis of H2O2 accumulation and regulation in these two lines showed that this compound is more rapidly and strongly produced in DZA45. 5 epidermal cells. This line has also a more elevated basal peroxidase activity than F83005. 5 (the most susceptible line). These results indicated that reactive oxygen species might play a role in DZA45. 5 to control the disease extent. In the Mt-Ae pathosystem, A17 (partially resistant) and F83005. 5 (susceptible) were selected for further cytological and genetic analyses. Microscopy analyses of root sections revealed that A17 partial resistance to Ae was linked to the protection of the central cylinder. Pericycle cell divisions, lignin deposition around the pericycle and accumulation of soluble phenolic compounds were found to be involved in A17 stele protection. Genetic analyses of resistance were performed with the RIL population (A17 x F83005. 5) and identify one major QTL, named Ae1, on the top of chromosome 3. .
Verrier, Eloi. "Bases génétiques de la résistance aux rhabdovirus et réponse cellulaire chez la truite arc-en-ciel : importance des mécanismes de défense innés." Phd thesis, AgroParisTech, 2013. http://pastel.archives-ouvertes.fr/pastel-00914894.
Sivadon-Tardy, Valérie. "Analyse moléculaire des populations de Staphylococcus epidermidis associées aux infections ostéo-articulaires." Versailles-St Quentin en Yvelines, 2011. http://www.theses.fr/2011VERS0018.
In a first prospective distribution study, we show that Staphylococcus epidermidis accounts for more than 80% cases of prosthetic joint infections (PJIs) associated with coagulase negative staphylococci. However, the prevalence of this species is also very high among per-operative "non-significant" isolates. Thus we tried to identify relevant pathogenicity markers by studying polymorphism of S. Epidermidis autolysin/adhesin AtlE cell wall anchoring domain and the presence of several markers (mecA, icaA/D, IS256, « ACME »), in association with « ST » as determined by MLST. ST2, atle allele 1, mecA, icaA/D, IS256 - but not ACME - were significantly associated with PJIs strains. Finally, we show using MLST and MLVA that strains with abnormal susceptibility to glycopeptides belong to a limited number of STs but are genetically diverse
Lachaux, Marlène. "Caractérisation de nouvelles sources de résistance aux souches africaines de Xanthomonas oryzae pv. oryzae, agent de la bactériose vasculaire du riz." Thesis, Montpellier, 2022. http://www.theses.fr/2022MONTG011.
Bacterial Leaf Blight (BLB), caused by the Gram-negative bacterium Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating diseases of rice in West Africa and Asia. Xoo injects through its type-III secretion system a full cocktail of TAL ("Transcription Activator-Like") effectors into the host plant cell. By means of their nuclear localization signals (NLS) TALEs are next imported into the host nucleus where they bind through central tandem repeats to host promoter targets at a sequence called EBE ("Effector Binding Element"), with the final aim of initiating gene transcription thanks to their activation domain (AD). Xoo is thus able to modulate the expression of plant genes by hijacking the plant transcriptional machinery and induce so-called susceptibility (S) genes that favor the development of the bacterium and disease consequently. In some cases, TALEs can activate so-called executor (E) genes whose expression leads to plant defense reactions and results in resistance. Genetic diversity analyses have shown that Xoo is comprised of two lineages that corresponding to strains from Africa for one and Asian strains for the other. African and Asian Xoo differ in their number of tal genes, but also in the type of resistance they elicit. Noteworthy, none of the races identified in Africa have been found in Asia.The objective of this thesis was to identify sources of resistance in rice in order to provide new strategies for the control of BLB in Africa. In a gain-of-function approach, preliminary analyses identified several TALEs of the Malian strain MAI1 with potential avirulence activity on the rice varieties IR64, CT13432 and FKR47N. To further confirm these results, a loss-of-function approach was undertaken, consisting in the inoculation of a library of BAI3Δtal mutants deriving from the Xoo Burkinabe strain BAI3, whose TALome (tal genes repertoire) is very similar to that of MAI1, on each of the three resistant varieties. This work validated the avirulence role of TalD and TalI on the matching rice varieties IR64 and CT13432, respectively. We also showed that the resistance exhibited by CT13432 against MAI1 and BAI3 results of the combination of two resistance mechanisms, one based on the TalI-mediated induction of an as yet unknown executor gene, and the other on an allele of the Xa1 resistance gene. In a second step, in order to deepen our knowledge on the resistance conferred by IR64 to African Xoo strains, the screening of a population of recombinant inbred lines of F11 generation, resulting from the cross between the resistant variety IR64 and the susceptible variety Azucena, was conducted. This study confirmed two QTL, qABB-7 and qABB-11, previously reported in another study, and also identified four new QTL of resistance against African Xoo strains. Finally, RNAseq analyses were performed on the resistant variety IR64 and the susceptible variety Nipponbare, which genomes are sequenced, to characterize their transcriptome in response to African Xoo. The avirulence activity of TalD in IR64 being demonstrated, a comparison of the differential expression of genes induced by MAI1 and BAI3 with the BAI3ΔtalD mutant was performed, allowing the identification of potential candidate E-genes induced by TalD in IR64. This work represents a first step in the development of new strategies based on the deployment of sustainable sources of resistance to control BLB in Africa
Ollier, Marine. "Sélection d’un Triticale à faible teneur en mycotoxines." Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1R003.
Fusarium head blight (FHB) is a cereal disease of major importance responsible for yield losses and mycotoxin contaminations in grains. Here we characterized the resistance to FHB in triticale breeding material harboring resistance factors from bread wheat. Additionally, we introduce a new measurement approach to quantify FHB severity on grains based on the evaluation of the whitened kernel surface (WKS) using digital image analysis. A highly FHB resistant experimental line which derives from a triticale × wheat cross was crossed to several modern triticale cultivars to generate three triticale populations. These mapping populations were phenotyped for Fusarium head blight resistance in replicated field trials under artificial inoculation and were genotyped with genotyping-by-sequencing (GBS) and SSR markers. FHB severity was assessed in the field by visual scorings and on the harvested grain samples by a digital evaluation of the WKS. Aside from this breeding work, the applicability of WKS was assessed on two bread wheat and one triticale grain sample sets with 265 samples in total. Pearson correlation coefficients between Fusarium‐damaged kernels (FDK) and WKS range from r = 0.77 to r = 0.81 and from r = 0.61 to r = 0.86 for the correlation between deoxynivalenol (DON) content and WKS. As a low‐cost and fast approach, this method appears particularly attractive for breeding and genetic analysis of FHB resistance where typically large numbers of experimental lines need to be evaluated, and for which WKS is suggested as an alternative to visual FDK scorings. Four QTL with major effects on FHB resistance were identified in our three mapping populations. They map to chromosomes 2B, 3B, 5R and 7A. The QTL on 3B collocated with Fhb1 and the QTL on 5R with the dwarfing gene Ddw1. This is the first report demonstrating the successful introgression of Fhb1 into triticale which comprises a significant step forward for enhancing FHB resistance in this crop
Kadner, Maxime. "Développements méthodologiques et applications en biologie translationnelle de techniques d'édition du génome chez le blé tendre." Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0029.
A major challenge for agriculture will be its capacity to feed the world in the 21st century in the face of climate change and population growth, while meeting the need for agro-ecological transition. Bread wheat (Triticum aestivum) will be a key issue, and biotechnologies a key tool to be mobilised. Three lines of research involving the CRISPR-Cas tool were addressed in this PhD. First, we evaluated the use of alternative enzymes to Cas9, in particular for their ability to perform multiple mutations simultaneously. We tested the Cas12a enzyme, recognising a different PAM from Cas9 and generating a cohesive cleavage site, as well as the CAS9-NG enzyme, recognising a shorter PAM than Cas9. We obtained very interesting results since we were able to induce up to 16 mutations simultaneously in the same plant, which is particularly encouraging for the future use of this tool in varietal selection programmes. Secondly, we sought to carry out targeted insertion of stop codon cassettes in order to induce more precise gene silencing than is currently possible. Preliminary results obtained by transient expression and analysed by nested PCR have shown that numerous targeted insertion events can be demonstrated, that undesirable degradation events occur preferentially at the ends of the cassette compared to the ends of the genomic DNA generated by the CRISPR-Cas cut, as well as an asymmetry in the occurrence of stochastic DNA insertion events at the ends of the cassette. However, we did not succeed in regenerating a plant with a stable insertion, which implies that a joint improvement of transformation and integration efficiencies will have to be achieved to reach this goal. The results obtained have been the subject of a patent application by the industrial partner, and a publication has been written for submission after the eventual acceptance of the patent. The third axis of our thesis had an applicative vocation of the tools developed in the first two axes on the theme of disease resistance. Indeed, as the agro-ecological transition induces a drastic reduction of synthetic pesticides, a special effort must be made to improve genetic control of diseases, which implies major research efforts to understand plant-pathogen interactions. In this context, in collaboration with the MDC laboratory of the GDEC, we focused on 20 candidate genes for Fusarium head blight (FHB) susceptibility in wheat. The results obtained show that it is possible to extinguish three genes simultaneously, which was previously impossible using conventional mutagenesis techniques. The resulting plant will be phenotyped for its pathogen resistance profile. Taken together, the results of the thesis show that the CRISPR systems are capable of reaching a large number of loci simultaneously in common wheat, and that a targeted insertion of a small DNA fragment is possible but with a very low frequency in stable transformation in the current state of the technology. These results could be applied for the first time to solve the problem of phenotyping QTLs associated with weak effects. They show the need to master and develop these new technologies to answer research questions. These results are also a step towards using editing techniques to support varietal selection, for example by deleting previously identified susceptibility genes in elite varieties. Implications for breeding programmes and possible developments in the light of EU regulatory guidelines are discussed
Pépin, Geneviève. "Résistance au virus Y de la pomme de terre (PVY) chez des lignées transgéniques de pomme de terre exprimant un inhibiteur de protéases de type cystéine." Thesis, Université Laval, 2004. http://www.theses.ulaval.ca/2004/22301/22301.pdf.