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1
Collin, François. "The tolerance of wheat (Triticum aestivum L.) to Septori tritici blotch". Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49156/.
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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 availability 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.
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Marques, Leandro Nascimento. "Fertilizante foliar em associação com fungicida em trigo". Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/5110.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe Chemical control of diseases is the most used practice in wheat. The increase in mineral nutrition with foliar fertilizers has been a promising alternative for the plant resistance against leaf diseases. However, foliar fertilizers have been applied in association with fungicides and can change the performance of the fungicide on diseases control. This study aimed to evaluate the applicability of foliar fertilizer in combination with azoxystrobin + cyproconazole fungicide in wheat, based on biochemical, physiological , nutritional and yield parameters and determine the interference caused by the fertilizer on the evolution of leaf diseases in wheat. Isolated application rates of fertilizer and application in combination with the fungicide were performed on field and in the greenhouse works. The application of fertilizer increased the plant growth, green leaves and enhanced pigments levels (Chl a, Chl b and carotenoids). When the fungicide was applied with fertilizer, it reduced the stresses effect generated by fungicide application; it increased parameters of chlorophyll fluorescence, Fv / Fm and ETR. The levels of N, P and K in the leaves increased after fertilizer application. The fertilizer mixed with fungicide did not reduce the fungicide uptake. The diseases control was better when fertilizer was mixed with fungicide. The fertilizer applied alone had no effect on the diseases. Yield parameters were increased due to application of fungicide and foliar fertilizer.
O controle químico de doenças com o uso de fungicidas é umas das práticas mais empregadas na cultura do trigo em função da eficácia de controle. Incrementos na adubação mineral com fertilizantes foliares tem sido uma alternativa promissora em busca de maior resistência as doenças. Entretanto, fertilizantes foliares são comumente aplicados associados a fungicidas e podem interferir no desempenho de controle do produto. Este trabalho teve por objetivo avaliar a aplicabilidade do fertilizante foliar em mistura com o fungicida azoxistrobina + ciproconazol na cultura do trigo, com base em parâmetros bioquímicos, fisiológicos, nutricionais e produtivos e determinar a interferência causada pelo fertilizante sobre a evolução de doenças foliares na cultura. A partir da aplicação isolada de doses do fertilizante e da aplicação em associação com o fungicida foram realizados trabalhos a campo e em casa de vegetação. A aplicação do fertilizante refletiu em maior crescimento das plantas, manutenção de folhas verdes e maiores teores de pigmentos (Chl a, Chl b e carotenóides). Quando aplicado junto ao fungicida, o fertilizante teve efeito mitigatório dos estresses gerados pela aplicação do fungicida, com reflexos positivos em parâmetros da fluorescência da clorofila a, Fv/Fm e ETR. Houve aumento dos teores de N, P e K nas folhas em função do fertilizante foliar. Não houve redução da absorção do ingrediente ativo azoxistrobina + ciproconazol em mistura com o fertilizante. Houve melhor resposta de controle das doenças em função da mistura do fertilizante com o fungicida. O fertilizante isolado não teve nenhum efeito sobre as doenças. Parâmetros produtivos foram incrementados em função da aplicação do fungicida e do fertilizante foliar.
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Jordan, Faron. "Strobilurin resistance in Septoria tritici". Thesis, University of Nottingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.478958.
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Nashaat, N. I. "Resistance mechanisms to Erysiphe graminis f.sp. tritici in Triticum timopheevii and a hexaploid derivative". Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371772.
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Ali, Solaf Jawhar. "Investigating secondary metabolism in Zymoseptoria tritici". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687598.
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One of the most serious fungal diseases of wheat is Septoria tritici Blotch caused by Zymoseptoria tritici. This disease is typified by an asymptomatic latent phase, followed by a rapid onset on host-cell necrosis. There has long been debate about whether the necrosis is due to production of secondary metabolite toxins or other effects of the fungus such as use of small protein effectors thereby providing nutrients for fungal growth. Secondary metabolites are mainly classified into polyketides (PKs), non-ribosomal peptides (NRPs), alkaloids and terpenes. Genome analysis of Z. tritici identified nine PKS and two hybrid PKS NRPS pathways in addition to the NRPS believed to be responsible for siderophore biosynthesis. Promoter: GFP fusions were made for all of these candidate toxin synthase genes and their expression followed in vitro and through the disease cycle by confocal microscopy, however only pPKS3 gave any apparent GFP expression in planta. Disruption of PKS3 did not generate any mutant phenotype. In fungi, the phosphopantetheine transferase (PPTase) is needed not only for the PKS and NRPS activation, but also both lysine and siderophore synthesis and its disruption in Z. tritici is reported to have very reduced virulence. The Z. tritici alpha-aminoadipate reductase (Lys2) gene was disrupted and the ZtΔlys2 mutant was auxotrophic for lysine. Furthermore, the pathogenicity testing of ZtΔlys2 on wheat showed a significant reduction in symptom development and the pycnidia and spore number compared with a wild type. In a parallel experiment, ornithine N hydroxylase (SidA) was disrupted to prevent hydroxamate siderophore synthesis. The resulting ZtΔlys2 mutant was unable to synthesise ferrichrome and required supplementation with a high concentration of iron. It was more sensitive to oxidative stress compared with wild type and showed reduction of pycnidia and spore numbers. Whilst L1PPTstrain shows reduced virulence, the impacts of lysine and iron uptake are sufficient to account for the reduction in virulence so given that these genes also had very low if any expression in planta, it is unlikely that PKS and hybrid PKS NRPS play a major role in disease of Z. tritici.
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Kankwatsa, Peace. "Genetic Studies of Rust Resistance in the Triticum spp., and Puccinia graminis f. sp. tritici Pathosystem". Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15805.
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The challenge posed by rapidly changing wheat rust pathogens in both pathogenicity and environmental adaptation calls for the application of advanced techniques, so that efforts to breed for durable disease resistance can be sped up. This study was carried out to examine genetic variability among Australian pathotypes of Puccinia graminis f. sp. tritici (Pgt), and to identify leaf rust, stem rust and stripe rust resistance genes in Africa wheat germplasm and spring wheat landraces. Phenotypic and genotypic analysis of Pgt isolates representing two putative clonal lineages determined that pathotypes 326-1,2,3,5,6 (founding pathotype of Lineage 3) and 194-1,2,3,5,6, (Lineage 4) had a common genetic background. Simple sequence repeat (SSR) analysis showed clearly high similarity among isolates from Lineages 2, 3 and 4. Thirty-four SSR genotypes characterised by low genetic variation (FST = 0.042) were identified among 142 isolates. Genetic variation among genotypes in such clonal pathogen populations are believed to arise principally from single-step mutation. Both known and unknown seedling and APR genes functioning either singly or in combinations were detected in African germplasm and landraces. Presence of resistance genes effective against multiple rust pathogens is an asset for gene pyramiding. Known adult plant resistance (APR) genes including the pleiotropic linked genes [Lr34/Yr18/Sr57; Lr46/Yr29/Sr58; Lr67/Yr46/Sr55 and Sr2/Lr27/Yr30], Lr68 and Lr74 were identified. A genome-wide association study detected 77 SNP markers significantly associated with rust resistance genes/quantitative trait loci (QTLs) in landraces. Finally, SNPs associated with resistance to multiple pathogens, SNPs mapped in chromosome positions not previously known for rust resistance and landraces/lines carrying USR and UAPR are promising new sources of resistance.
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Aung, Theingi Soe Taing. "Molecular polymorphism and virulence in Pyrenophora tritici-repentis". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62687.pdf.
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Pijls, C. F. N. R. M. J. "Population genetics of fungicide resistance in Septoria tritici". Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308103.
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Kock, Appelgren Petra S. "Investigating disease tolerance to Zymoseptoria tritici in wheat". Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/41161/.
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Disease tolerance is defined as the ability to maintain grain yield in the presence of disease and could be a potential defence mechanism to be incorporated into breeding programmes. It is an attractive goal, as disease tolerance has the potential to be a broad-spectrum, durable defence mechanism while exerting little selection pressure on pathogen populations. Relatively little is known about how disease tolerance is conferred, but most of the hypotheses suggest resource capture and resource-use traits such as large green canopy area, increased light extinction coefficient and a high source to sink balance. Disease tolerance in current wheat genotypes is generally associated with low yield potential, and for disease tolerance to be incorporated into commercial breeding it is important to determine whether this link can be disassociated. In this study, an attempt was made to identify physiological traits conferring disease tolerance to Septoria tritici blotch (STB) in winter wheat. Wheat genotypes contrasting in disease tolerance were selected for in-depth phenotyping of selected physiological traits to determine their association with disease tolerance. A number of publications have attempted to link disease tolerance to physiological traits in wheat, based on their yield loss to disease symptom relationship. However, in this study it was proposed that variation in non-symptomatic disease could influence the appearance of disease tolerance which has not previously been investigated. The ratio of in-leaf pathogen biomass to visual disease symptoms was studied in both controlled-environment experiments and in field experiments to determine whether a high in-leaf pathogen biomass was associated with disease tolerance. Two field experiments were conducted during the field seasons 2011/12 and 2013/14 at Teagasc Oak Park, Carlow, Ireland and ADAS Rosemaund, Herefordshire, UK, respectively. A field experiment was also conducted in 2012/13 at Teagasc Oak Park, but due to dry conditions and little disease presence this field experiment was excluded from nearly all experimental analyses. In each experiment, there were two fungicide treatments, non-target disease control and full disease control. In order to increase genetic variability, 38 selected lines from a L14 x Rialto doubled-haploid (DH) mapping population developed by the International Maize and Wheat Improvement Centre (CIMMYT) were screened alongside 10 UK-adapted reference genotypes for contrasting disease tolerance in 2012. Tolerance was quantified as yield loss per unit of green lamina area index (GLAI) loss to disease. L14 is a CIMMYT spring wheat large-ear phenotype advanced line and Rialto is a UK winter wheat which has high radiation-use efficiency and stem soluble carbohydrate. The DH lines displayed an increased range of disease tolerance compared to the UK-adapted reference genotypes. Selected genotypes were subjected to in-depth phenotyping for an extended range of physiological traits in 2014 to identify traits associated with increased disease tolerance. The traits measured included pre- and post- anthesis radiation interception, light extinction coefficient at anthesis, pre- and post anthesis radiation-use efficiency and stem water soluble carbohydrate accumulation at ear emergence + 7 days. In general, there was a wide range of physiological traits displaying weak associations with disease tolerance. The main traits associated with disease tolerance were related to large and/or maintained source capacity in the presence of disease, such as increased GLAI at anthesis and increased post-anthesis light interception. There was also a general association with low grain yield in the absence of disease and decreased harvest index. Increased disease tolerance was associated with high source capacity and low sink capacity, and there was an association between a high source to sink balance, measured as increased Healthy Area Duration (HAD) per grain, and disease tolerance. The impact of genotype variation on the amount of non-symptomatic disease to visual disease expression was investigated in controlled-environment (CE) experiments. In-leaf Zymoseptoria tritici fungal biomass (pathogen load) was quantified by a Real Time qPCR assay targeting the β-tubulin gene (Accession no. AY547264) and compared to visual disease expression. In the first CE experiment, two wheat genotypes were exposed to increasing concentrations of Z. tritici inoculum. There were differences in rates of pathogen development and pathogen presence between inoculum concentrations in both visual disease symptoms and pathogen loads. In the following CE experiment, a wider range of genotypes exposed to a high inoculum level were shown to differ significantly in the relationship between visual disease symptoms and pathogen loads. In order to determine the impact of genotype variation on the visual disease symptoms to pathogen load ratio, flag leaves of genotypes screened for in-field disease tolerance in 2012 and 2014 were analysed. Large variations in the disease symptoms to pathogen load ratio were identified, which has not previously been shown in wheat experiments. An attempt was made to relate the visual symptoms – pathogen load ratio to non-lesion green area loss as a measure of a potential metabolic cost of increased pathogen pressure, but no such relationship was found. An increased pathogen load per unit visual symptoms did not account for larger yield losses than predicted for a given disease level and there was no direct relationship between symptom expression - pathogen load ratios and disease tolerance. The consistency of high/low displays of disease tolerance calculated by different disease measures was investigated using three different ways of measuring disease; HAD, area under disease progress curve (AUDPC) and pathogen DNA quantified by qPCR. In general, the two measures of pathogen presence (AUDPC and pathogen load) tended to quantify disease tolerance similarly, while the HAD-based tolerance contrasted. There were also differences in which traits were associated with disease tolerance for the different methods of calculating tolerance; the calculations based on AUDPC and pathogen DNA tended to associate a decreased source capacity to disease tolerance while the HAD-based tolerance indicated an association with increased source capacity. All methods, however, indicated that a low yield potential was associated with disease tolerance. In conclusion, there was a large range of disease tolerance found in the field experiments compared to previous investigations. The HAD-based disease tolerance seems to be mainly related to a large source capacity and a low sink capacity. However, the genotype ratings of high/low disease tolerance and associated physiological traits seem to vary according to the method of calculating tolerance. There were large differences in the ratio of visual symptoms-pathogen load between genotypes; even though this did not have a direct impact on disease tolerance or yield loss it could potentially be associated with increased metabolic costs.
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Sidhu, Yaadwinder Singh. "Molecular tools for functional genomic analyses of the stealth pathogenesis of wheat by Zymoseptoria tritici". Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/20219.
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Zymoseptoria tritici is an ascomycete fungus that causes Septoria tritici leaf blotch disease, which is one of the most devastating diseases of wheat. The lack of molecular tools has withheld functional genomics and consequently has left extensive gaps in the knowledge of the biology of infection by Z. tritici. The current research was conducted to develop molecular tools in order to facilitate forward and reserves genetic screens in Z. tritici. These tools include an optimised genetic manipulation protocol, the Z. tritici strains that provide high frequency targeted genome manipulations, a strategy for gene overexpression and protein tagging, and regulatable promoters for controlled gene expression in Z. tritici. The regulatable promoters served to reveal that the Z. tritici β-(1,3)- glucan synthase (BGS1) gene encoded an essential protein, which regulated cell wall stress tolerance and was therefore, a potential drug target. In addition, these molecular tools revealed a virulence-associated role of the glyoxylate cycle in Z. tritici as inactivation of this pathway impeded pre-penetration morphogenesis, which was restored by exogenous glucose application. This result implied that Z. tritici engaged the glyoxylate cycle to produce energy though gluconeogenesis by channelling the by-products of lipolysis. This significance of the glyoxylate cycle during initiation of the bi-phasic infection cycle suggests that Z. tritici is not a hemibiotroph, but a necrotrophic pathogen with an extended asymptomatic phase of infection. Overall, the molecular tools developed in this study will facilitate large-scale functional genomic analyses to interrogate the biology of infection by Z. tritici. The resulting data will inform the development of durable control strategies to combat Z. tritici outbreaks.
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Reges, Juliana Teodora de Assis. "Biologia e estrutura genética de populações do patógeno da brusone do trigo no centro-sul do Brasil : Pyricularia pennisetigena e P. zingibericola de gramíneas invasoras infectam braquiária, cevada e trigo: Estrutura genética de populações contemporâneas do patógeno da brusone do trigo (Pyricularia graminis-tritici sp. nov.) no centro-sul do Brasil /". Botucatu, 2016. http://hdl.handle.net/11449/144456.
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Orientador: Paulo Cezar CeresiniResumo: Na primeira parte de nosso estudo descrevemos a associação de Pyricularia pennisetigena e P. zingibericola a gramíneas invasoras de áreas de trigo no centro-sul do Brasil. Desconhece-se, entretanto, qual o potencial de P. pennisetigena e P. zingibericola como patógenos de poáceas de interesse econômico para a agricultura brasileira. Dessa forma, objetivamos caracterizar o espectro de patogenicidade de P. pennisetigena e P. zingibericola a braquiária, cevada e trigo e compará-lo com aP. grisea e com a espécie até até recentemente descrita como P. oryzae patotipo Triticum, de ocorrência generalizada no agroecossistema brasileiro. Foram testados 20 isolados de Pyricularia spp. obtidos de amostras de folhas infectadas de plantas invasoras de campos de trigo. A classificação dos isolados em espécies distintas de Pyricularia foi efetuada usando-se filogenia molecular baseada nas sequencias parciais dos genes actina e calmodulina. Pyricularia pennisetigena e P. zingibericola inoculadas em folhas, foram patogênicas a braquiária, cevada e trigo, com diferenças na agressividade entre as espécies. Pyricularia zingibericola foi a espécie mais agressiva a braquiária e cevada, enquanto P. pennisetigena foi a espécie mais agressiva em plantas jovens de trigo. Por outro lado, P. grisea isolada de Digitaria sanguinalis ou de Urochloa spp. não infectou trigo. A análise filogenética das regiões ACT e CAL concatenadas reproduziu as relações filogenéticas e a magnitude das diferenças descritas e... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In the first part of our study we described the association Pyricularia pennisetigena and P. zingibericola associated with invasive grasses from wheat cropping areas in South-Central Brazil. Howeever, the potential of P. pennisetigena and P.zingibericola as pathogens to poaceous plants of economic interest for Brazilian agriculture is still unknown. Thereforne, this study aimed to characterize the pathogenicity spectrum of P. pennisetigena and P. zingibericola to signal grass, barley and wheat and compare with P. grisea and with the species until recently described as P. oryzae pathotype Triticum, of widespread occurrence in the Brazilian agro-ecosystem. Twenty isolates of Pyricularia spp. obtained from samples of infected leaves of weed species in wheat fields were tested. Classification of isolates into different species of Pyricularia was performed using molecular phylogeny based on the partial actin and calmodulin gene sequences. Pyricularia pennisetigena and P. zingibericola inoculated on leaves were pathogenic to signal grass, barley and wheat, with differences in aggressiveness between species. Pyricularia zingibericola was the most aggressive species to signal grass and barley, while P. pennisetigena was the most aggressive species to young plants of wheat. On the other hand, P. grisea isolated from Digitaria sanguinalis or Urochloa spp. did not infect wheat. Phylogenetic analysis of the concatenated regions ACT and CAL reproduced the phylogenetic relationships and ... (Complete abstract click electronic access below)
Doutor
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Ahmadi, Firouzabad Abdolhadi. "Introgression of resistance to powdery mildew (Erysiphe graminis f.sp. tritici) from alien species into bread wheat (Triticum aestivum)". Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340688.
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Zurn, Jason Daniel. "Characterization and Identification of Genetic Resistance to Puccinia Graminis F. Sp. Tritici in Triticum Aestivum and Hordeum Vulgare". Diss., North Dakota State University, 2015. http://hdl.handle.net/10365/25236.
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Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a major threat to wheat (Triticum aestivum) and barley (Hordeum vulgare) production. The emergence of the highly virulent Ug99-lineage stem rust races has stimulated research toward the identification and characterization of rust resistance genes in wheat and barley. Populations were developed to elucidate the inheritance and location of Pgt resistance genes in the common wheat landraces PI 626573 and PI 362698. The resistance present in PI 626573 was shown to be conferred by a single dominant gene (SrWLR) and was mapped to a 1.9 cM region on the long arm of chromosome 2B. This region is known to contain Sr9h which is effective against Ug99. SrWLR provides resistance to Pgt race RKQQC and Sr9h does not, suggesting SrWLR may be a new gene or allele of Sr9. Subsequent work has delimited the SrWLR region to 0.36 cM using a synteny-based approach. QTL analysis of the PI 362698 population using Pgt races identified significant (P < 0.1) resistance QTLs on multiple chromosomes. QTLs identified on chromosome 3B map to a similar location as Sr12 which does not provide resistance to Ug99-lineage races, suggesting a new allele or novel resistance gene. The QTLs identified on chromosomes 2B and 6A are thought to be Sr16 or an allele of Sr28 and Sr8a. Sr57 is known to be present in PI 362698 and is thought to be associated with Pgt QTLs detected on chromosome 7D. QTLs on chromosomes 5A and 5B are in regions where Pgt resistance genes have not been previously identified. Relative qPCR, fluorescence microscopy, and infection type approaches were utilized to phenotype barley for seedling resistance to Pgt race MCCFC at multiple time points. Statistical differences (P < 0.05) were found between accessions at 24 hours post inoculation using qPCR and displayed similar hierarchical ordering to microscopy observations. At early stages, the susceptible cultivar Steptoe had less fungal DNA than barley accessions containing resistance genes suggesting potential pre-haustorial resistance contributions. Temporal variation in resistance ranking suggests the qPCR assay may be valuable for dissecting pre- and post-haustorial resistance mechanisms.North Dakota Wheat Commission
American Malting Barley Association
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Schäuble, Andreas. "Septoria Tritici - Bedeutung, Biologie und Bekämpfung des Erregers der Weizenblattdürre". [S.l. : s.n.], 2005. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11759389.
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Vidal, Tiphaine. "Intérêt de la diversité architecturale des plantes cultivées pour limiter la progression épidémique de maladies foliaires à dispersion pluviale : cas de la septoriose au sein d'associations variétales de blé". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLA012/document.
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La culture d’associations de variétés sensibles et résistantes au sein d’une même parcelle permet de réduire la propagation des maladies fongiques foliaires aériennes. L’architecture des plantes a un impact sur la dispersion de spores et le microclimat, mais est rarement prise en compte dans la conception des associations. L’objectif de cette thèse était de comprendre le rôle joué par l’architecture dans des associations de variétés différant par leur niveau de résistance à une maladie dispersée par éclaboussement, la septoriose du blé, causée par Zymoseptoria tritici. Une expérimentation en conditions contrôlées a permis de quantifier des relations entre interception de spores et architecture des couverts. Des différences de densité entre couverts purs et associés ont donné lieu à une réduction du niveau de maladie sur les plantes sensibles cultivées en association par rapport à celles cultivées pures. Lors d’une expérimentation au champ, les associations de variétés de hauteurs de tiges contrastées étaient moins malades que celles ayant des hauteurs similaires. Ces résultats ont été mis en relation avec des effets de l’architecture sur la dispersion de spores et la durée d’humectation au sein des couverts. Une approche de modélisation spatialement explicite a permis d’identifier des mécanismes de dispersion par éclaboussement liés à l’architecture des couverts associés. Dans des associations de variétés de hauteurs différentes, la quantité d’inoculum éclaboussée dépendait de la surface foliaire présente au dessus des feuilles malades (effet parapluie). La quantité d’inoculum interceptée par un étage foliaire était liée à la différence de hauteur entre la source d’inoculum et l’étage foliaire (effet hauteur). Les différences de hauteur de plantes entre variétés d’une association ont modulé l’interception de spores par des feuilles résistantes (effet barrière). Nos résultats suggèrent qu’une prise en compte de l’architecture des variétés dans la conception des associations variétales permettrait de mieux maîtriser les maladies par éclaboussementGrowing mixtures of susceptible and resistant cultivars in the same field makes it possible to reduce the propagation of airborne fungal plant diseases. Plant architecture has an impact on spore dispersal or microclimate, but is rarely taken into account in mixture design. The objective of this work was to understand the role of canopy architecture in mixtures of cultivar of different levels of resistance to a disease dispersed by rain-splash, septoria tritici blotch, caused by Zymoseptoria tritici. A controlled conditions experiment made it possible to quantify relationships between spore interception and canopy architecture. Differences of canopy density between pure stands and mixtures led to a reduction in disease on susceptible plants grown in mixture, compared to the susceptible pure stand. During a field experiment, mixtures of cultivars with contrasted stem height were less diseased than those with similar stem height. These results were related to the effect of canopy architecture on spore dispersal and leaf wetness duration. A spatially explicit modeling approach made it possible to identify splash dispersal mechanisms related to the architecture of mixed canopies. In mixtures of cultivar with diverse plant height, the amount of splashed inoculum depended on leaf area located above diseased leaves (umbrella effect). The amount of inoculum intercepted by a leaf layer was related to its difference of height between the inoculum sources (height effect). Differences of plant height between cultivars composinga mixture modulated the interception of spores by resistant leaves, providing an increased protection of susceptible leaves (barrier effect). Our results suggest that considering cultivar architecture in the design of cultivar mixtures could make it possible to improve the management of splash-dispersed diseases
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Henze, Matthias. "Entwicklung einer anbauparameter- und witterungsabhängigen Befallsprognose von Septoria tritici". Göttingen Cuvillier, 2007. http://d-nb.info/987969234/04.
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Arraiano, Lia Susana. "Genetics of resistance of wheat to septoria tritici blotch". Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390648.
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The research described in this týesis was focused on achieving a better understanding of the genetics of resistance of wheat to septoria tritici blotch (Mycosphaerella graminicola). Firstly, a detached leaf technique that could be a useful complement to field trials and an alternative to whole seedling assays in assessing cultivar resistance and investigating the genetics of the host-pathogen interaction was developed. Sets of inter-varietal substitution lines, developed at the John Innes Centre, involving known and possible sources of resistance to septoria tritici blotch, were tested with several single-pycnidium isolates in both the seedling and the adult plant stage. Two specific resistance genes were identified on chromosomes of `Synthetic 6x' and `Bezostaya 1'. A resistance gene, named Stb5, was identified using the M. graminicola isolate IP094269 and mapped on the short arm of chromosome 7D of `Synthetic 6x'. `Bezostaya I's specific resistance gene to IP0323 seems to be located in the same region as Stb6, and is indeed likely to be the same gene. `Bezostaya 1' and `Cappelle Desprez' also seemed to carry components for partial resistance. Triticum macha resistance to septoria tritici blotch on the other hand was both of a specific and isolatenon- specific nature. The specific components carried by T. macha seemed to be the Stb6 gene and an additional resistance gene, but it was not possible to identify their chromosomal location. To evaluate the relationship of heading date and plant height components to severity of septoria tritici blotch, an F6 single seed population of `Apollo' x `Thesee' was studied in natural conditions. Septoria tritici blotch levels were substantially lower in later-heading than in earlier-heading lines. Total plant height had comparatively little effect on disease severity, but increased distance between the two upper leaves increased disease levels. `Apollo' seems to carry partial resistance involving more than one QTL.
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Dooley, Hilda. "Fungicide-resistance management tactics : impacts on Zymoseptoria tritici populations". Thesis, University of Reading, 2015. http://centaur.reading.ac.uk/49314/.
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Azoles and Succinate Dehydrogenase Inhibitors (SDHIs) are the main fungicides available for septoria tritici blotch control, causal agent Zymoseptoria tritici. Decline in azole sensitivity, in combination with European legislation, poses a threat to wheat production in Ireland. Azole fungicides select CYP51 mutations differentially; it was hypothesised that using combinations of azoles could be an effective anti-resistance tool. Naturally inoculated field experiments were carried out in order to understand the impacts of using combinations of azoles, epoxiconazole and metconazole, on azole sensitivity. Approximately 3700 isolates were isolated and their sensitivity to both azoles analysed. Findings showed that limiting the number of applications, by alternating each fungicide, slowed selection for reduced azole sensitivity. Limiting azole use by reducing doses did not reduce selection for decreased azole sensitivity. Although not complete, cross-resistance was observed between the two azoles, which will lead to general reduction in azole sensitivity. A sub-selection of isolates from each treatment at each location were analysed for changes in the CYP51 gene. Sequence analysis identified 49 combinations of mutations in the CYP51 gene, and three different inserts in the CYP51 promoter. Intragenic recombination also featured in these populations. Baseline studies of five new SDHIs were carried out on 209 naturally infected, non-SDHI-treated isolates. With the exception of fluopyram, cross-resistance was apparent between the SDHIs. Analysis of 2300 isolates found that when compared to the solo products, mixing the SDHI isopyrazam and the azole epoxiconazole increased epoxiconazole sensitivity, but had no apparent effect on isopyrazam sensitivity. SDHI resistance-conferring mutations were absent in the baseline and experimental isolates. As long as azoles are used, Z. tritici populations will continue to evolve towards resistance. Combining different modes-of-action, SDHIs and multi-sites, with azoles will relieve some of that selective pressure. To get the best out of available fungicides, they should be used in combination with host resistance and good crop management practices.
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Marchegiani, Elisabetta. "The MAPK Slt2 regulates development and pathogenicity in Zymoseptoria tritici". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112013.
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Zymoseptoria tritici est l'un des dix plus importants champignons pathogènes des plantes. Son impact économique sur la production de blé et ses caractéristiques biologiques (dimorphisme levure-hyphae, hémi-biotrophie, populations sexuées et diversifiées) fait de Z. tritici un organisme unique parmi les champignons pathogènes des plantes. Au cours des dix dernières années, il a suscité un intérêt croissant de la communauté scientifique conduisant au développement d'outils génomiques et génétiques. Ces efforts ont permis de mieux comprendre les mécanismes impliqués dans sa pathogénie et son évolution. Nous avons focalisé notre étude sur les trois «Mitogen-Activated Kinases» (MAPK) ZtFus3, ZtHog1 et ZtSlt2 de Z. tritici nécessaires au succès de l’infection. Nous avons réalisé une caractérisation phénotypique détaillée du mutant de délétion ZtSLT2 lors de l'infection du blé et du développement fongique in vitro. Nous avons montré que le mutant ΔZtslt2 est non pathogène pour les feuilles de blé, même lorsque la pénétration stomatique est court-circuitée par injection de spores dans la feuille, ce qui suggère que ce mutant présente un défaut dans la colonisation des tissus de la plante. Pendant la croissance in vitro, ZtSLT2 est nécessaire à la pigmentation, des colonies, l’émergence des hyphes aériens, la formation de biofilm et l’hydrophobicité de la colonie. Ces phénotypes sont des marqueurs d'un processus développemental qui se produit pendant le vieillissement de la colonie de Z. tritici (développement de colonies pigmentées et hydrophobes portant des hyphes aériens blancs). Ce processus développemental survient à des moments différents selon le milieu de culture et la température, le plus rapide étant sur milieu pauvre «Pomme de terre Glucose» (PD) à 25 °C (4 jours) et le plus lent sur milieu riche complet «Extrait de Levure, Peptone, Glucose» (YPD) à 18 °C (18 jours). Nous avons montré que les gènes codant pour des enzymes impliquées dans la biosynthèse de la mélanine, des α-1,3-glucanes et des hydrophobines sont surexprimées au cours de ce processus développemental dans la souche sauvage, en particulier après trois jours de culture sur PD à 25 °C par rapport aux autres conditions. Cette surexpression nécessite que la voie ZtSLT2 soit fonctionnelle. L’analyse transcriptomique (RNAseq) de ces conditions différentielles est en cours pour identifier le réseau de gènes nécessitant la protéine Slt2 pour leur expression. Ces gènes cibles de ZtSLT2 sont des facteurs de pathogénicité putatifs.Nous avons également développé un nouvel outil moléculaire pour Z. tritici. Nous avons montré que les promoteurs pMoNIA1 et pZtNIA1 des gènes codant les nitrates réductases de Magnaporthe oryzae et Z. tritici, respectivement, sont régulés par la source d’azote du milieu de la même façon chez Z. tritici. L’expression de gènes sous le contrôle de ces deux promoteurs est maximale en présence de nitrate comme seule source d'azote, mais réduite en présence de glutamate. Ces promoteurs peuvent donc être utilisés pour l'expression conditionnelle de gènes et le remplacement de promoteur chez Z. tritici. Ils seront utiles pour contrôler l'expression des allèles constitutivement actifs des MAP kinase kinases dans le but d’activer les voies des MAPK de manière conditionnelleZymoseptoria tritici is one of the ten more important fungal plant pathogens. Its economic impact on wheat production and its biological characteristics (yeast-fungal dimorphism, hemi-biotrophy, sexual and highly diverse populations) make Z. tritici unique among fungal plant pathogens. It has therefore drawn attention of the scientific community during the last ten years, leading to the development of genomic and genetic tools. These efforts have improved our understanding of its pathogenicity and evolution. We have focused our study on the three Z. tritici Mitogen-Activated Protein Kinase (MAPK) signalling pathways (ZtFUS3, ZtHOG1, and ZtSLT2) which are required for pathogenicity. We provided novel insights in the role of ZtSlt2 MAPK signalling pathway using a detailed phenotypic characterization of SLT2 deletion mutant during wheat infection and in vitro development. We showed that SLT2 is non-pathogenic on wheat leaves, even when stomatal penetration is bypassed by spore injection, suggesting a defect in leaf colonisation. During in vitro growth, SLT2 is required for melanisation, aerial hyphae emergence, biofilm formation and colony hydrophobicity which are markers of a developmental switch occurring during Z. tritici colony aging (development of melanised and hydrophobic colonies supporting abundant white aerial hyphae). This developmental switch occurs at different times depending on media and temperatures, quickest being on poor plant-derived Potato Dextrose (PD) medium at 25°C (4 days) and slowest on rich complex Yeast Extract Peptone Dextrose (YPD) medium 18°C (18 days). We provided evidence that genes encoding enzymes involved in both melanin and α-1,3-glucan biosynthesis, and hydrophobins are up-regulated during this developmental switch in wild type, in particular at 3 days on PD at 25°C compared to other conditions. This up-regulation clearly requires a functional ZtSLT2 pathway. Transcriptomic analysis (RNAseq) of these differential conditions is ongoing to identify the network of genes requiring SLT2 for their expression. These SLT2 target genes are putative pathogenicity factors. We also provide a new molecular tool for Z. tritici. We showed that pMoNIA1 and pZtNIA1 promoters from nitrate reductases encoding genes of Magnaporthe oryzae, and Z. tritici, respectively, are nitrogen-responsive in Z. tritici to a similar extent. They are fully expressed in presence of nitrate as sole nitrogen source and down-regulated in presence of glutamate, showing they are suitable for conditional gene expression and promoter replacement in Z. tritici. These promoters will be useful to control the expression of constitutively active alleles of MAP Kinase kinases in order to activate MAPK pathways in a conditional manner
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Tayeh, Christine. "Induction de résistances chez le blé (Triticum aestivum L.) lors d’une interaction compatible avec Blumeria graminis (DC. E.O Speer) : mécanismes mis en jeu après applications de tréhalose et d’heptanoyl d’acide licylique, dérivé fonctionnalisé de l’acide salicylique". Thesis, Littoral, 2012. http://www.theses.fr/2012DUNK0521.
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L’utilisation de molécules stimulatrices des défenses des plantes (SDP), également appelées inducteurs de résistance, constitue une alternative potentielle aux traitements fongicides conventionnels pour combattre les maladies dues à des champignons phytopathogènes. Trois SDPs, le tréhalose (TR), l’acide salicylique (SA) et l’heptanoyl d’acide salicylique (HSA), un dérivé fonctionnel du SA, protègent le blé (Triticum aestivum L.) contre l’oïdium (Blumeria graminis f.sp. tritici), lorsqu’ils sont utilisés de façon préventive. La protection obtenue n’est pas liée à un effet fongistatique direct sur la germination des spores du champignon, mais à l’induction chez le blé de défenses qui diminuent le développement de la maladie. Notre travail consistait à caractériser les mécanismes de défense mis en jeu après applications foliaires de TR, de HSA et de SA chez un cultivar de blé sensible à l’oïdium. Un suivi de l’expression de gènes marqueurs de défense, réalisé par RTqPCR, a été mené en cinétique,depuis le traitement par les SDPs jusqu'à 4 jours après infection. Les activités enzymatiques correspondantes ont été également mesurées, et l’influence indirecte des SPDs sur le processus infectieux a été observé en microscopie in planta. Ainsi, les réactions de défense déclenchées par le TR, le SA et le HSA ralentissent l’évolution de l’infection, jouant respectivement sur la germination des conidies, structures infectieuses de Bgt, sur la germination du tube germinatif appressorial (AGT) et sur la proportion d’AGTs qui parviennent à pénétrer dans les tissus foliaires. Le TR est à l’origine d’une augmentation de l’expression des gènes codant pour une lipoxygénase, une protéine de transfert des lipides et une phospholipase C, impliquées dans le métabolisme lipidique et la signalisation, et de gènes codant pour des protéines PR comme les chitinases et PR1, tous connus comme marqueurs de défense. Ainsi, les réactions déclenchées par le TR correspondent à un effet inducteur de défenseplutôt qu’à une réaction de stress osmotique. Le HSA modifie particulièrement le métabolisme lipidique, en induisant fortement et pendant toute la cinétique, l’expression du gène codant pour la LOX et l’activité correspondante, aussi bien hors contexte infectieux qu’en contexte infectieux. Cette augmentation de l’activité LOX n’est pas retrouvée chez des feuilles traitées au SA et caractérise donc le HSA. L’importance des réactions observées avec le TR, le SA et le HSA, hors contexte infectieux et en présence de Bgt amène à discuter les effets éliciteurs et potentialisateurs de ces 3 SDPsThe use of plant elicitors, also known as resistance inducers, is an alternative to conventional fungicides to control diseases caused by phytopathogenic fungi. Three resistance inducers, trehalose (TR), salicylic acid (SA) and heptanoyl salicylic acid (HSA), a functional derivative of SA, protect wheat (Triticum aestivum L.) against powdery mildew (Blumeria graminis f . sp. tritici) when applied prior to infection. The protection obtained is not linked to any direct fungistatic effect on the fungal spore germination, but to the induction of wheat defences that impair the development of the disease. Our work aimed at characterizing the defence mechanisms triggered after foliar applications of TR, HSA and SA in a wheat cultivar susceptible to powdery mildew. Monitoring of defence markers genes expression by RTqPCR was conducted during a time-course experiment from the treatment time until 4 days after infection. Corresponding enzyme activities were also measured, and the indirect influence of elicitors on the infectious process was observed by microscopy in planta. Thus, defence responses triggered by TR, SA and HSA slow the progression of the infection, respectively altering the germination of infectious structures such as conidia, the differentiation of appressorial germ tube (AGT) and the proportion of AGTs that manage to penetrate the epidermis. TR causes an increase in the expression of genes encoding a lipoxygenase, a lipid transfer protein and a phospholipase C, which are involved in lipid metabolism and signaling, and genes encoding for PR-proteins such as chitinases and PR1, all known as markers of defence. Thus, the reactions triggered by TR match with the ones triggered during induced defence rather than during osmotic stress response. HSA specifically targeted lipid metabolism, inducing strongly and throughout the time-course, the expression ofthe gene encoding LOX and the corresponding enzyme activity, both in infectious and non-infectious contexts. This increase in LOX activity was not found in leaves treated with SA and thus characterizes HSA mode of action. The importance of the reactions observed with TR, SA and HSA, in non-infectious conditions and in the presence of Bgt have to be considered regarding either elicitation or potentiation
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Muchembled, Jérôme. "Le couple Triticum aestivum/Erysiphe (= Blumeria) graminis f. Sp. Tritici : induction de la résistance acquise, incidences sur la composition lipidique". Littoral, 1999. http://www.theses.fr/1999DUNK0027.
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L'oïdium du blé est une maladie cryptogamique causée par Erysiphe graminis f. Sp. Tritici (Egt). L’infection des feuilles conduit à des pertes de rendement en grains relativement important. La lutte contre cet agent pathogène passe par l’épandage de fongicides, ce qui peut conduire à des problèmes environnementaux. Nous avons recherché des substances biologiques ou des composés chimiques non toxiques capables d’éliciter les défenses naturelles de la plante. L’association de ces substances avec des fongicides pourrait permettre d’en diminuer les doses pour une protection identique. Après la mise au point d’un protocole fiable d’évaluation de la contamination, nous avons testé lors de traitement préventif plusieurs substances potentiellement élicitrices. Des fractions non purifiées (broyats foliaires de blé ou de spores d’Egt, hydrolysat acide du mycélium de Septora nodorum) et des produits purifiés (β cyclodextrine, tréhalose et salicylyl heptanoate) ont été expérimentées. Hormis la β cyclodextrine, tous les produits ont conféré une bonne protection (30 à 90%). Ils sont tous inefficaces lors de traitement curatif. Certains de ces produits ont été testés quant à leur capacité à éliciter l’activité d’une enzyme : la Phenylalanine Ammonia Lyase (PAL). La PAL intervient non seulement dans la réaction de lignification, mécanisme de défense du blé, mais aussi dans la synthèse de l’acide salicylique ou de phytoalexines, autres métabolites intervenant dans les défenses des plantes. La PAL peut donc être considérée comme un bon marqueur des réactions d’élicitation. Les conidies d’Egt, le tréhalose et l’hydrolysat du mycélium de Septoria nodorum sont capables d’induire son activité de manière différente. Les capacités du tréhalose et du salicylyl heptanoate à induire des modifications du métabolisme lipidique chez le couple ont été étudiées. Il a d’abord fallut déterminer la composition en acides gras et en stérols de chacun des protagonistes. S’il s’avère que la composition en acides gras des feuilles de blé est relativement classique (par ordre d’importance, C16 :0, C18 :1, C18 :0, C18 :2 et C18 :3) ; des acides gras particuliers à très longues chaînes ont été identifiés chez les conidies d’Egt (de C12 à C24). Notons la présence de deux acides gras particuliers identifiés par CG-MS, les C22 :0 et C24 :0 méthoxydés en position β. La question qui se pose est de savoir si ces molécules sont naturellement présentes dans les conidies ou s’il s’agit d’acides gras qui se méthoxylent au cours de l’extraction. La question n’est pas complètement élucidée. La composition en stérols de feuilles de blé montre la prédominance du sitostérol puis du 24-méthylcholestérol, de l’isofucostérol et du stigmastérol. Chez les conidies, nous avons montré que les stérols majoritaires étaient le 24-méthylènecholestérol et le 24-éthylcholestérol. Cependant, nous avons montré que les proportions relatives des stérols et des acides gras variaient considérablement avec l’âge des conidies. Le 24-méthylènecholestérol et les acides gras à très longues chaînes sont les lipides prédominants de conidies âgées tandis que le 24-éthylcholestérol et les acides gras à courtes chaînes sont les lipides majoritaires de conidies jeunes. Les conidies produites sur les plantes traitées par le salicylyl heptanoate présentent des modifications importantes de leur proportion relative en acides gras et en stérols tandis que les feuilles traitées n’en présentent pas. Ces modifications sont similaires à celles observées en fonction de l’âge des conidies.
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Tiley, Anna Mystica Mendez. "Investigating asexual sporulation in Zymoseptoria tritici, a fungal pathogen of wheat". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715767.
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Habig, Michael [Verfasser]. "Function and transmission of accessory chromosomes in Zymoseptoria tritici / Michael Habig". Kiel : Universitätsbibliothek Kiel, 2019. http://d-nb.info/1177033399/34.
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Rawlinson, Catherine. "Characterising the specialised metabolism of the wheat Pyrenophora tritici-repentis interaction". Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/82846.
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The necrotrophic fungal pathogen Pyrenophora tritici-repentis (Ptr) causes the economically damaging tan spot disease of wheat. The project investigates the specialised metabolites (SMs) utilised by the pathogen for interaction with the host. This thesis describes the first characterised biosynthetic gene cluster in Ptr, the first report of an amide containing phthalide and the first structurally characterised small molecule necrotrophic effector. Characterisation of host-pathogen holds significant potential in developing control strategies for tan spot disease.
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Ortelli, Silvano. "Zusammenhang zwischen der Resistenz gegen Braunrost (Puccinia recondita Rob. ex Desm. f. sp. tritici) und der Ertragsbildung bei Winterweizen (Triticum aestivum L.) /". [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10789.
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Strelkov, Stephen E. "Purification and mode of action of PTR, Pyrenophora tritici-repentis, chlorosis toxin". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23516.pdf.
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Janakiraman, Vasantharajan. "Characterization of the lignification response in the wheat-Pyrenophora tritici-repentis system". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq62642.pdf.
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Mann, Ruth Louise. "Suppression of Septoria tritici by foliar applied potassium chloride on winter wheat". Thesis, University of Wolverhampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322183.
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The effect of foliar applied potassium chloride on Septoria tritici on winter wheat was quantified and possible modes of action investigated by in vitro, glasshouse, controlled environment and field experiments between 1996 and 1999. In vitro experiments showed that as the concentration of potassium chloride increased, mycelial growth and germination of conidia decreased (EO sos of 1.36M and 0.7M, respectively). One glasshouse and two field experiments showed a significant reduction in the leaf area affected by S. trttict after foliar application of potassium chloride compared to untreated controls. In general, application of potassium chloride reduced the leaf area affected by S. tritici by 20 -.40%. However, a significant yield increase was not observed. Potassium chloride applied to the lower leaves of winter wheat did not confer systemic acquired resistance against S. tritici on the upper leaves. Inhibition of conidial germination, on leaf surfaces by potassium chloride was observed. Similar inhibition was observed when polyethylene glycol, an inert osmoticum, was applied at the same calculated osmotic potential. During field experiments there was no significant difference in the leaf area affected by S. tritici in plots treated with potassium chloride or polyethylene glycol, although both significantly reduced the leaf area affected compared to untreated control plots. Therefore, the principal mode of action of potassium chloride was proposed to be as a result of adverse osmotic conditions caused by the salt on leaf surfaces. However, the addition of a range of adjuvants to potassium chloride did not increase the efficacy of S. tritici control in glasshouse studies. The results from this study show that potassium chloride, when applied to foliage of winter wheat can reduce the leaf area affected by S. tritici and it is proposed that this reduction was by adverse osmotic conditions caused by the salt on leaf surfaces.
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Möller, Mareike [Verfasser]. "Epigenome and chromosome dynamics in the fungal pathogen Zymoseptoria tritici / Mareike Möller". Kiel : Universitätsbibliothek Kiel, 2018. http://d-nb.info/1163603767/34.
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Noble, Rosalind Christina. "Identification of LysM effector proteins in the wheat pathogenic fungus, Zymoseptoria tritici". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.701972.
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Zymoseptoria tritici is an important foliar pathogen of Triticum aestivum (cultivated wheat). Control of Septoria tritici blotch disease in the field, caused by Z. tritici, is mainly facilitated by fungicidal chemical applications and planting of wheat breeds containing a combination of Septoria resistance loci (STB loci). Currently, molecular mechanisms underlying STB trait resistance are not fully understood and efficacy and availability of chemical fungicides is limited. In order to improve control of this disease in the field requires greater understanding of the processes underlying successful wheat infection. Secreted "effector" proteins enable plant pathogenic fungi to manipulate host defences for successful infection. Characterisation of effector proteins, demonstrating an important function during wheat infection may provide a novel approach to developing new disease control strategies, as well as aiding in our understanding of disease dynamics. Secreted Lysin Motif-containing (LysM) proteins are now well-known effector molecules deployed by fungal pathogens, as originally defined for the Extracellular protein 6 (Ecp6) gene in Cladosporium fulvum. Using homology and in silico analysis three putative LysM containing secreted effector genes were identified in the Zymoseptoria tritici genome. Gene sequencing analysis confirmed they are highly conserved in multiple Z. tritici isolates. Expression analysis indicates two of these genes, Mycosphaerella graminicola 1LysM (Mg1L) and Mycosphaerella graminicola 3LysM (Mg3L), are highly expressed during symptomless wheat infection. Collaborative protein functional analysis indicates a role in chitin-binding and protection against plant defence compounds for Mg1L and Mg3L. Mutational analysis indicates that Mg3L in particular, plays an essential role during Z. tritici wheat infection. This represents the first fully characterised effector protein in Z. tritici and emerges alongside functional characterisation of LysM effector proteins in other plant pathogenic species e.g. Magnaporthe oryzae Secreted LysM Proteinl (Slp1). Mg3L protein orthologues are found in many plant pathogenic ascomycete fungal genomes and two plant pathogenic oomycete genomes.
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Ennaïfar, Sabah. "Protection intégrée contre le piétin-échaudage (Gaeumannomyces graminis tritici) du blé d'hiver". Rennes, Agrocampus, 2006. http://www.theses.fr/2006NSARA045.
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Gaeumannomyces graminis var. Tritici est un champignon tellurique pathogène responsable du piétin-échaudage des céréales à paille qui peut être à l'origine de pertes de rendement importantes. Le développement de ce champignon dépend de nombreux facteurs liés à la succession de culture, àl'itinéraire technique, au climat et au sol. L'agriculteur peut contrôler le piétin échaudage et réduire son impact sur le rendement en modifiant le système de clture (succession culturale, semis tardif, fertilisation azotée, traitement fongicide etc. ). A ce jour aucun outil d'aide à la décision n'a été développé pour définir de nouvelles méthodes de protection intégrée contre le piétin-échaudage du blé. L'objectif de ce travail est de développer un modèle simulant l'effet des systèmes de culture sur le piétin-échaudage en fonction de variables d'entrée facilement accessibles. Préalablement à ce travail de modèlisation, des expérimentations ont été conduites en 2001 – 2003 afin d'étudier l'effet du mode de gestion de l'interculture sur le développement du champignon. En effet, la succession culturale joue un rôle très important. Cependant elle a jusqu'ici été analysée sans prise en compte de la période d'interculture. Cinq couverts végétaux (colza, moutarde, ray-grass, repousses de blé, avoine) et un maintien du " sol nu " entre deux cultures de blé ont été comparés. En monoculture de blé aucun effet lié à la gestion de l'interculture n'a été observé sur le piétin-échaudage. Le niveau faible de maladie causé par le déclin explique cette absence d'effet. Entre une première et une deuxième année de culture de blé, le risque le plus élevé a été observé après les repousses de blé, le lus faible après un sol maintenu " nu " sans couvert. Le colza (cv Lutin) est sans effet alors que moutarde (cv Carnaval) et avoine (cv Ourasi) donnent les meilleurs résultats (après "sol-nu "), mais principalement lorsque leurs résidus sont enfouis avant le semis de bléGaeumannomyces graminis var. Tritici is a soiborne fungus responsible of the take-all of cereals. This disease causes I mportant yield losses. The development of the fungus depends on many factors : crop rotation, crop management, climate and soil conditions. Farmers can control take-all and reduce its impact on yield by modifying their cropping systems (crop succession, late sowing, nitrogen fertilization, seed treatment, etc). So far no decision-support tool has been developed for the design of new methods of integrated crop protection against take-all of winter wheat. This work aims at developing a model to simulate cropping systems and climate effects on take-all using easy-to-measure input variables. Preliminary to the modelling work, however, several field experiments were conducted I the years 2000-2003 to estimate the effect of the summer-fallow period management on take-all. This factor was not studied in detail in previous studies. Five summer-crops (oilseed rape, mustard, ryegrass, oats, wheat volunteers) plus a bare soil situation were compared. In wheat monoculture, summer-fallow management had no effect on take-all. This was explained by reduced levels of disease related to take-all decline. Between first and second wheat crops, the highest risk was observed following wheat volunteers, and the lowest following the bare soil. Oilseed rape (cv Lutin) did not show any significant effect on take all incidence, whereas mustard (cv Carnaval) and oast (cv Ourasi) were the best candidates. These summer-crops decreased disease incidence and severity particularly when their residues were buried before wheat sowing
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Sari, Bruno Giacomini. "Tamanho de amostra para a avaliação de doenças em experimentos com arroz e trigo". Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/5142.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe blast and the yellow leaf spot are the major rice and wheat, respectively, both are commonly found as for its destructive potential. Because of this, proving the efficiency of control methods through experiences is of paramount importance, since these results will be used as reference for technicians and producers. The precision is related to the choice of suitable design (local control), the number of repetitions, the sample size in the field, among others. In the case of control experiments involving fungicides, which is the main method of controlling both diseases, leaf sampling in installments is necessary because measuring the entire population becomes unviable. Sampling generates a new error (sampling) within the plot, and this should be minimized by appropriate sampling strategy. Thus, this study aimed to determine sample sizes needed to assess the severity of rice leaf blast and the yellow spot of wheat. For this reason, results of chemical control experiments performed during harvests and 2009/2010 2010/2011 were used. The procedure for collection and analysis of data was identical in all experiments, regardless of culture. In all, the diseases were measured at seven, 14 and 21 days after application of fungicides by sampling 10 leaves in the plots. The variables were disease severity and area under the disease progress curve (AUDPC). Data were subjected to analysis of variance to obtain the experimental and sampling errors, and so, by hypothesis test to check whether the sample dimension and the number of repetitions were adequate. The departure from randomness of variable severity was tested in order to determine whether the methodology used to calculate the sample size was adequate. The departure from randomness test showed that both diseases behaved were distinct, both among treatments between assessments, sometimes distributing randomly in the field, sometimes not. Thus, the combination of theoretical distributions (indicating random or clustered distribution of the disease in the field) to the formula used to calculate the sample size is inadequate. The sample size necessary to measure the average disease severity in the plots was not the same in all treatments and between assessments. This result is expected since, in most of the experiments, the average of the disease was different between treatments and between evaluations. This result leads to a constant change in the relationship between the variance and the mean, which is indicative of the disease in the field of dispersion, this dispersion that is related to the sample intensity. Finally it was observed that, to measure the average AUDPC variable, it is necessary to evaluate fewer leaves in the plots.
A brusone da folha e a mancha amarela são as principais doenças do arroz e do trigo, respectivamente, tanto por serem comumente encontradas quanto pelo seu potencial destrutivo. Devido a isso, a comprovação da eficiência de métodos de controle através de experiências é de suma importância, uma vez que estes resultados serão usados como referência por técnicos e produtores. A precisão experimental está relacionada com a escolha adequada do delineamento (controle local), do número de repetições, do tamanho da amostra na parcela, entre outros. No caso de experimentos de controle envolvendo fungicidas, que é o principal método de controle de ambas as doenças, a amostragem de folhas nas parcelas é necessária, pois mensurar toda a população torna-se inviável. A amostragem gera um novo erro (amostral) dentro da parcela, e este deve ser minimizado através de um dimensionamento amostral adequado. Deste modo, o presente trabalho teve por objetivo determinar tamanhos de amostra necessários para avaliar a severidade da brusone da folha do arroz e da mancha amarela do trigo. Para isso, foram utilizados resultados de experimentos de controle químico realizados durante as safras 2009/2010 e 2010/2011. O procedimento de coleta e análise dos dados foi idêntica em todos os experimentos, independente da cultura. Em todos eles, as doenças foram mensuradas aos sete, 14 e 21 dias após a aplicação dos fungicidas através da amostragem de 10 folhas nas parcelas. As variáveis estudadas foram a severidade das doenças e a área abaixo da curva de progresso das doenças (AACPD). Os dados foram submetidos a análise de variância para a obtenção dos erros experimental e amostral, e assim, através do teste de hipótese, verificar se o dimensionamento amostral e o número de repetições foram adequados. O afastamento da aleatoriedade da variável severidade foi testado com o objetivo de determinar se a metodologia utilizada no cálculo do tamanho da amostra foi adequada. O teste de afastamento da aleatoriedade mostrou que ambas as doenças comportaram-se de foram distintas, tanto entre os tratamentos quanto entre as avaliações, ora distribuindo-se de forma aleatória no campo, ora não. Desse modo, a associação de distribuições teóricas (que indicam distribuição aleatória ou agregada da doença no campo) à formula utilizada no cálculo do tamanho da amostra é inadequado. O tamanho de amostra necessário para mensurar a média da severidade das doenças nas parcelas não foi o mesmo em todos os tratamentos e entre as avaliações. Este resultado era esperado, uma vez que, na grande maioria dos experimentos, a média das doenças foi distinta entre os tratamentos e entre as avaliações. Este resultado levou a uma constante mudança na relação entre a variância e a média, que é um indicativo da dispersão da doença no campo, dispersão esta que esta relacionada com a intensidade amostral. Por fim observou-se que, para mensurar a média da variável AACPD, é necessário avaliar menos folhas nas parcelas. Deste modo, recomenda-se que, sempre que possível, utiliza-se a variável AACPD como forma de comparação entre os tratamentos.
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Al-Hamar, Bader. "The effects of biotic and environmental factors on host-pathogen differential interactions in wheat- Mycosphaerella graminicola pathosystem". Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325133.
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Payne, Andrew Charles. "Molecular identification and characterisation of novel targets in Mycosphaerella graminicola, and the development of screening technologies for fungicide discovery". Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326693.
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Schotanus, Klaas [Verfasser], i Eva H. [Akademischer Betreuer] Stukenbrock. "Epigenetics of the plant pathogen Zymoseptoria tritici / Klaas Schotanus. Betreuer: Eva H. Stukenbrock". Marburg : Philipps-Universität Marburg, 2015. http://d-nb.info/107686564X/34.
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Hopkinson, Sarah J. "Puccinia graminis f.sp. tritici, race c17 : physiology of uredospore germination and germtube differentiation". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27957.
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Germinating uredospores of race C17 of Puccinia graminis f.sp. tritici form characteristic infection structures (appressorium, infection peg, vesicle, infection hypha) in response to a 1.5 h heat shock at 29° C administered 2 h after germination at 19° C. The proportion of sporelings forming infection structures was augmented by nutrients, n-nonyl alcohol and, an appropriately timed heat shock. The heat shock temperature required to induce maximum differentiation had a very precise optimum which varied slightly for each spore lot. Variations one degree above or below this optimum reduced the percent differentiation by greater than 40%. The presence of an inhibitor of protein synthesis, puromycin, in the germination medium: (1) prevented uredosporeling differentiation but had no effect on germination, (2) significantly reduced the proportion of germtubes forming appressoria, and (3) in most cases prevented the division of germtube nuclei. It was concluded that essential differentiation-specific proteins are synthesized from the onset of germination, throughout the formation of appressoria and to the completion of differentiation. These results were consistent with the observed effects of heat shock on the rate of protein hydrolysis. During germination there was a net hydrolysis of protein leading to an increase in size of the endogenous pool of free amino acids and to an increased leakage of amino acids to the germination medium. Heat shock effectively reduced the amount of endogenous free amino acids and the extent to which amino acids were lost to the medium. It was concluded that in heat shocked sporelings protein synthesis was increased relative to protein hydrolysis by comparison with the relative rates of these two processes in germinating (non-shocked) uredosporelings. Moreover, there was no net protein synthesis during the formation of infection structures induced by heat shock. The loss of amino acids to the germination medium was selective, particularly in heat shocked sporelings.Land and Food Systems, Faculty of
Graduate
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Toupin, Eymond Donald. "Microscopic examination of the effects of Ptr, Pyrenophora tritici-repentis, ToxA on wheat". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0020/MQ53128.pdf.
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Dodd, Thomas. "The impact of Septoria tritici on the photosynthetic and carbohydrate metabolism of wheat". Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269286.
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Gulart, Caroline Almeida. "INFLUÊNCIA DO ESPECTRO DE GOTAS NO DESEMPENHO DE FUNGICIDAS NA CULTURA DO TRIGO". Universidade Federal de Santa Maria, 2013. http://repositorio.ufsm.br/handle/1/3603.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorLeaf rust and leaf spots caused by Bipolaris sorokiniana and Drechslera tritici-repentis, are diseases that dramatically reduce the productivity of wheat. Depending on the difficulty in having cultivars resistant to all diseases, chemical control is an alternative, technically and economically viable. To maximize the residual of fungicides is necessary to optimize the factors related with spray minimizing the losses due to disease incidence. The goal of the work was to determine the influence of the number of drops in the penetration of fungicides and its control efficacy at various stages of application. The experimental design used was randomized block in Split plot design, totaling 20 treatments and four replications. The treatments were two wheat cultivars (Fundacep Cristallino and Fundacep Nova Era); three spray tips (XR 11002, TJ 60-11002 and TX 8002); 3 fungicides: Pyraclostrobin + Epoxiconazol; Epoxiconazol and Pyraclostrobin, and a control without any application. It was evaluated the density of drops per square centimeter, DMV, DMN, severity of disease, weight of hectoliter and productivity of the crop. The use of fungicides pyraclostrobin and epoxiconazol + piraclostrobia, respectively, provided the better control of diseases, higher productivity and greater weight of hectoliter in Nova Era cultivar. On the other hand, Cristalino cultivar with lower impact of the diseases did not show difference on efficacy of the fungicides used. The control of diseases was influenced by the DMV/DMN ratio due to the use of different spray tips. Tips with thin/medium drop spectrum performed better coverage at the lower part of the canopy, providing fewer establishments of the diseases. The correlation between the variables showed that the second application of fungicides was the one that crashed in the calculation of the area under the curve of progress of diseases (AACPD), hectoliter weight and yield. The greater disease pressure at flowering can explain this result.
A Ferrugem da folha e as manchas foliares causadas por Bipolaris sorokiniana e Drechslera tritici-repentis, são doenças capazes de reduzir drasticamente a produtividade da cultura do trigo. Em função da dificuldade em dispor de cultivares resistentes a todas as doenças, o controle químico é uma alternativa viável, técnica e economicamente. Para maximizar o residual dos fungicidas é necessário otimizar os fatores relacionados à tecnologia de aplicação minimizando os danos em função da incidência das doenças. O objetivo do trabalho foi determinar a influência do número de gotas na penetração dos fungicidas e na sua eficácia de controle em diferentes momentos de aplicação. O delineamento experimental utilizado foi de Blocos ao acaso em parcelas subsubdivididas, totalizando 20 tratamentos em quatro repetições. Os tratamentos foram constituídos por duas cultivares de trigo (Fundacep Cristalino e Fundacep Nova Era); três pontas de pulverização (XR 11002, TJ 60-11002 e TX 8002); 3 fungicidas: Piraclostrobina + Epoxiconazol; Epoxiconazol e Piraclostrobina, mais uma testemunha sem aplicação. Foi avaliada a densidade de gotas por centímetro quadrado, diâmetro mediano volumétrico (DMV), diâmetro mediano numérico (DMN), severidade das doenças, peso do hectolitro e produtividade da cultura. A utilização dos fungicidas epoxiconazol+ piraclostrobina e piraclostrobina, respectivamente, proporcionaram o melhor controle de doenças, melhor produtividade e maior peso do hectolitro na cultivar Nova Era. Por outro lado, na cultivar Cristalino submetida a um menor impacto das doenças, não houve diferença com relação aos fungicidas utilizados. O controle de doenças foi influenciado pelo espectro de gotas proporcionado devido a utilização das diferentes pontas de pulverização. Pontas com espectro fino/médio apresentaram melhor cobertura do terço inferior do dossel, proporcionando menor estabelecimento das doenças. A correlação entre as variáveis mostrou que a segunda aplicação dos fungicidas foi a que mais impactou no calculo da área abaixo da curva de progresso das doenças (AACPD), produtividade de grão e peso do hectolitro. Esse resultado pode ser explicado pela maior pressão de doença no estádio de florescimento.
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Liu, Sixin. "Molecular marker analysis of adult plant resistance to powdery mildew in common wheat". Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/11236.
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Powdery mildew, caused by Blumeria graminis (DC.) E.O. Speer f. sp. tritici E'm. Marchal (syn. Erysiphe graminis f. sp. tritici), is one of the major diseases of wheat (Triticum aestivum L.) worldwide. The use of cultivars with resistance to powdery mildew is an efficient, economical and environmentally safe way to control powdery mildew. Race-specific resistance has been extensively used in breeding programs; however, it is ephemeral. Adult plant resistance (APR) to powdery mildew is more durable as demonstrated by the cultivar Massey, which has maintained its APR to powdery mildew since its release in 1981. To develop an efficient breeding strategy, it is essential to understand the genetic basis of APR. The objectives of this study were to identify molecular markers associated with APR to powdery mildew in common wheat Massey and to verify their association using recombinant inbred (RI) lines.
A cross was made between the powdery mildew susceptible cultivar Becker and Massey. One hundred and eighty F2:3 lines were rated for disease severity under natural pressure of powdery mildew in field. Using both restriction fragment length polymorphism (RFLP) and microsatellite markers, three quantitative trait loci (QTL), designated as QPm.vt-1B, QPm.vt-2A and QPm.vt-2B, were identified in the Becker x Massey F2:3 generation. These loci are located on chromosomes 1B, 2A and 2B, respectively, and explained 17%, 29% and 11% of the total variation among F2:3 lines for powdery mildew resistance, respectively. Cumulatively, the three QTLs explained 50% of the phenotypic variation among F2:3 lines in a multi-QTL model. The three QTLs associated with APR to powdery mildew were derived from Massey and displayed additive gene action. QPm.vt-2B also fits a recessive model for APR to powdery mildew.
In the second part of this study, 97 RI lines were developed from the Becker x Massey cross. The RI lines were evaluated for APR to powdery mildew under natural disease pressure for three years. Both single marker analysis and interval mapping confirmed the presence of the three QTLs identified in the F2:3 generation. The three QTLs, QPm.vt-1B, QPm.vt-2A and QPm.vt-2B, accounted for 15%, 26% and 15% of the variation of mean powdery mildew severity of the RI lines over three years. In a multi-QTL model, the three QTLs explained 44% of the phenotypic variation of the RI lines. The RI lines were grouped according to the genotype of the three QTLs, represented by markers GWM304a, KSUD22 and PSP3100, respectively. The RI lines with Massey alleles at all three loci had a mean disease severity of 3.4%, whereas the RI lines with Becker alleles at all three loci had a mean disease severity of 22.3%. These severity values are similar to those of the corresponding parents.
The molecular markers identified and verified as to their association with APR to powdery mildew in Massey have the potential for use in marker-assisted selection for resistance to powdery mildew and in pyramiding powdery mildew resistance genes, as well as facilitating a better understanding of the molecular basis of APR to powdery mildew.Ph. D.
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Oliveira, Gustavo Migliorini de. "Momentos, doses e taxas de aplicação de fungicida no controle da ferrugem da folha (Puccinia triticina) e mancha amarela (Pyrenophora tritici repentis) do trigo". Universidade Estadual de Londrina. Centro de Ciências Agrárias. Programa de Pós-Graduação em Agronomia, 2012. http://www.bibliotecadigital.uel.br/document/?code=vtls000172097.
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O controle químico tem importante papel na triticultura brasileira, decorrente principalmente das doenças que assolam a cultura. Todavia, estudos relativos ao momento e tecnologia de aplicação, especialmente ligadas a taxa de aplicação e dose de fungicida, não são uma constante no contexto atual do manejo das enfermidades da cultura. Baseado nisto, conduziu-se três experimentos a fim de estudar momentos, doses e taxas de aplicação de fungicida para o controle da ferrugem da folha (P. triticina) e mancha amarela do trigo (P .triti-repentis). Os experimentos foram conduzidos na Universidade Estadual de Londrina, safra de 2010. Utilizou-se o coletor de esporos SIGA associado à dados climáticos e de previsão de tempo para auxiliar na tomada de decisão das aplicações de fungicidas. O primeiro experimento relativo ao momento de aplicação foi efetuado para o controle da ferrugem da folha no cultivar CD 104 - altamente susceptível a tal doença. Os tratamentos deste experimento constituiram-se de aplicações de funcigida (epoxiconazol + piraclostrobina) após 7, 14 e 21 dias após a manifestação sintomática no campo. O segundo e o terceiro experimento, culivares CD 104 e BRS 208, respectivamente, tiveram o objetivo de estudar a dose e taxa de aplicação de fungicida. No segundo, o delineamento experimental foi o fatorial 3 x 3 + testemunha sem controle, envolvendo os fatores dose (0,25, 0,30 e 0,35 L.ha-1) e taxa de aplicação (143, 286 e 429 L.ha-1), já no terceiro o delineamento experimental foi o fatorial 2 x 2 + testemunha sem controle, concernente aos fatores dose (0,2 e 0,3 L.ha-1) e taxa de aplicação (143 e 286 L.ha-1). Nestes dois últimos experimentos usou-se o fungicida ciproconazol + azoxistrobina. Em todos os experimentos o desenvolvimento das doenças foi avaliado periordicamente por meio do percentual de severidade das doenças, calculando-se a área abaixo da curva de progresso da doença (AACPD), bem como os índices de produtividades (kg.ha-1) e peso hectolitro (g). O experimento referente ao momento de aplicação no controle da ferrugem da folha do trigo demonstrou estatisticamente que o nível de severidade da doença aumentou com o atraso nas aplicações de fungicidas a partir dos 7 dias, ocasionando danos consideráveis à produtividade. Quanto aos experimentos relativos a dose e taxa de aplicação de fungicida, os resultados não evidenciaram nenhuma interação entre a dose e taxa de aplicação para nenhum dos experimentos, ou seja não houve efeito da concentração de fungicida na calda de pulverização. A taxa de aplicação e a dose de fungicida, em ambos os experimentos, somente exerceram influencia no controle da mancha amarela do trigo, cujo uso de maiores taxas e doses mostraram-se mais eficientes. No entanto, não foi verificado diferenças significativas para produtividade e peso hectolitro.Chemical control has an important role in the brazilian´s wheat field, mainly because of the diseases that attact the crop. However, studies envolving timing of application and spray technology - especially related to spray rates and dose of fungicide - are not a constant at the current management of wheat diseases. Based on this, it was conducted three experiments to study timming, doses and spray rates of application of fungicide to control leaf rust (P. triticina) and yellow spot (P. tritici-repentis) of wheat. The experiments were conducted at the State University of Londrina, 2010. It was used collector of spores SIGA associated with climate data and weather prediction to aid in the decision of the spray of fungicides. The first experiment concerning about timming of application was made to control leaf rust in the CD 104 cultivar - highly susceptible to this disease. The treatments of this experiment consisted of applications of funcigida (epoxiconazole + pyraclostrobin) after 7, 14 and 21 days after symptoms. The second and third experiment, CD 104 and BRS 208, respectivaly, studyed dose and spray rate of fungicide. In the second, experimental design was a factorial 3 x 3 + untreated control, involving the factors dose (0,25, 0,30 and 0,35 L.ha-1) and spray rate (143, 286 and 429 L.ha-1). In the third experiment the experimental design was a factorial 2 x 2 + untreated control, envolving the factors dose (0.2 and 0.3 L.ha-1) and spray rate (143 and 286 L.ha-1). In these last two experiments it was used the fungicide azoxystrobin + cyproconazole. In all of the experiments, the development of the diseases was accomplished through periodic evaluations about the percentage of severity, calculating after the area under the disease progress curve (AUDPC). It were also measured the yield (kg ha-1) and hectolitre weight (g). The experiment related about timming of application (leaf rust control) has shown statistically that the level of disease severity increased with the delay in the applications of fungicides from 7 days, causing considerable damage to yield. In the experiments about dose and spray rate of fungicide, the results showed any interaction between dose and spray rate for the two experiments, which denoted that there wasn`t effect of fungicide concentration in the spray. The spray rate and the dose of fungicide, in both experiments, just show influence in the control of yellow spot of wheat. The use of higher rates and doses were more effective. However, no significant differences was found for yield and hectolitre weight.
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Reges, Juliana Teodora de Assis [UNESP]. "Biologia e estrutura genética de populações do patógeno da brusone do trigo no centro-sul do Brasil". Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144456.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Na primeira parte de nosso estudo descrevemos a associação de Pyricularia pennisetigena e P. zingibericola a gramíneas invasoras de áreas de trigo no centro-sul do Brasil. Desconhece-se, entretanto, qual o potencial de P. pennisetigena e P. zingibericola como patógenos de poáceas de interesse econômico para a agricultura brasileira. Dessa forma, objetivamos caracterizar o espectro de patogenicidade de P. pennisetigena e P. zingibericola a braquiária, cevada e trigo e compará-lo com P. grisea e com a espécie até recentemente descrita como P. oryzae patotipo Triticum, de ocorrência generalizada no agroecossistema brasileiro. Foram testados 20 isolados de Pyricularia spp. obtidos de amostras de folhas infectadas de plantas invasoras de campos de trigo. A classificação dos isolados em espécies distintas de Pyricularia foi efetuada usando-se filogenia molecular baseada nas sequencias parciais dos genes actina e calmodulina. Pyricularia pennisetigena e P. zingibericola inoculadas em folhas, foram patogênicas a braquiária, cevada e trigo, com diferenças na agressividade entre as espécies. Pyricularia zingibericola foi a espécie mais agressiva a braquiária e cevada, enquanto P. pennisetigena foi a espécie mais agressiva em plantas jovens de trigo. Por outro lado, P. grisea isolada de Digitaria sanguinalis ou de Urochloa spp. não infectou trigo. A análise filogenética das regiões ACT e CAL concatenadas reproduziu as relações filogenéticas e a magnitude das diferenças descritas entre Pyricularia zingibericola, P. pennisetigena, P. oryzae patotipo Triticum e P. grisea. Urochloa spp. provavelmente representam fonte permanente de inóculo inicial dos patógenos da brusone do trigo entre as épocas de cultivo. Na segunda parte desta pesquisa, foi estudado a estrutura genética de populações do patógeno da brusone do trigo, o fungo Ascomiceto Pyricularia graminis-tritici sp. nov., no centro-sul do Brasil. Os objetivos foram responder às seguintes perguntas: As populações geograficamente distintas de P. graminis-tritici do trigo eram geneticamente subdivididas? Como se distribuía a diversidade gênica e genotípica entre as populações regionais de P. graminis-tritici, cerca de 30 anos após as primeiras epidemias de brusone no Brasil? Qual o sistema reprodutivo predominante de P. graminis-tritici no país? Conclui-se que não houve subdivisão na maioria das populações geográficas contemporâneas de P. graminis-tritici do trigo, indicando mecanismo eficiente de fluxo gênico. A magnitude e a extensão do fluxo gênico entre populações geográficas de P. graminis-tritici do trigo, o sistema reprodutivo predominantemente sexual, aliados a alta diversidade genética do fungo, indicam um patógeno com alto potencial evolutivo no agroecossistema brasileiro. Outras espécies de poáceas hospedeiras com ampla distribuição geográfica no Brasil, como por exemplo, o capim-braquiária (Urochloa brizantha), podem ter importante papel no ciclo de vida e na biologia reprodutiva, na sobrevivência e na dispersão do inóculo de P. graministritici a curta e longa distâncias, mantendo as populações geográficas do patógeno conectadas. Os padrões de fluxo gênico e genotípico entre populações hospedeiro-distintas do patógeno reforçam a hipótese de que a brusone do trigo pode ter tido origem de novo a partir de populações endêmicas de P. graminis-tritici que infectam outras espécies de poáceas (nativas ou invasoras de áreas de trigo) no país.
In the first part of our study we described the association of Pyricularia pennisetigena and P. zingibericola with invasive grasses from wheat cropping areas in South-Central Brazil. However, the potential of P. pennisetigena and P. zingibericola as pathogens to poaceous plants of economic interest for Brazilian agriculture is still unknown. Therefore, this study aimed to characterize the pathogenicity spectrum of P. pennisetigena and P. zingibericola to signal grass, barley and wheat and compare with P. grisea and with the species until recently described as P. oryzae pathotype Triticum, of widespread occurrence in the Brazilian agroecosystem. Twenty isolates of Pyricularia spp. obtained from samples of infected leaves of weed species in wheat fields were tested. Classification of isolates into different species of Pyricularia was performed using molecular phylogeny based on the partial actin and calmodulin gene sequences. Pyricularia pennisetigena and P. zingibericola inoculated on leaves were pathogenic to signal grass, barley and wheat, with differences in aggressiveness between species. Pyricularia zingibericola was the most aggressive species to signal grass and barley, while P. pennisetigena was the most aggressive species to young plants of wheat. On the other hand, P. grisea isolated from Digitaria sanguinalis or Urochloa spp. did not infect wheat. Phylogenetic analysis of the concatenated regions ACT and CAL reproduced the phylogenetic relationships and the magnitude of the differences reported between Pyricularia zingibericola, P. pennisetigena, P. oryzae pathotype Triticum and P. grisea. Urochloa spp. probably represents a permanent source of initial inoculum of the wheat blast pathogens between growing seasons. In the second part of this research, we studied the genetic structure of populations of the wheat blast pathogen, the Ascomycete fungus Pyricularia graminis - tritici sp. nov., in the South-Central Brazil. The objectives were to answer the following questions: The geographically distinct populations of P. graminis-triticiwheat were genetically subdivided? How gene and genotypic diversity were distributed among regional populations of P. graminis-tritici about 30 years after the first outbreaks of wheat blast in Brazil? What is the predominant reproductive system of P. graminis-tritici in the country? We concluded that there was no subdivision among most of the contemporary geographical populations of Pyricularia graminis- tritici from wheat fields, indicating an efficient mechanism of gene flow. The magnitude and extent of gene flow among geographical populations of P. graminis-tritici, the predominantly sexual reproductive system, coupled with high genetic diversity of the fungus, indicated a pathogen with high evolutionary potential in the Brazilian agro-ecosystem. Other species of poaceous hosts with wide geographic distribution in Brazil, for example, signal grass (Urochloa brizantha) can play an important role in the life cycle and reproductive biology, survival and spread of inoculum of P. graminis- tritici at short and long distances, keeping the geographical populations of the pathogen connected. The patterns of gene and genotypic flow between host-distinct populations of the pathogen reinforce the hypothesis that the wheat blast may had a de novo origin from endemic populations of P. graminis-tritici infecting other poaceous species (native or invasive WRwheat areas) in the country.
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Poppe, Stephan [Verfasser], i Eva [Akademischer Betreuer] Stukenbrock. "Host specialization in the fungal plant pathogen Zymoseptoria tritici / Stephan Poppe. Betreuer: Eva Stukenbrock". Marburg : Philipps-Universität Marburg, 2015. http://d-nb.info/1068315555/34.
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Engelmann, Uta [Verfasser]. "Kartierung und züchterische Nutzung von Resistenzen gegen die Weizenblattdürre (Pyrenophora tritici-repentis) / Uta Engelmann". Gießen : Universitätsbibliothek, 2014. http://d-nb.info/1068590882/34.
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Wake, Katherine Ann. "Host specificity and saponin resistance in oat-attacking isolates of Gaeumannomyces graminis var. tritici". Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301960.
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Kay, William Tudor. "Novel insights into the asexual life-cycle of the wheat-leaf pathogen Zymoseptoria tritici". Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/31538.
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Zymoseptoria tritici, the causal agent of Septoria tritici blotch (STB), is the most economically important pathogen of wheat in temperate climates. EU spending on the control of STB is estimated at more than € 1.3 billion per annum, even when tolerant cultivars are used. This thesis comprises 5 data chapters each looking to ascertain reasons for the success of Z. tritici. Using mainly in vitro methods combined with confocal microscopy, this thesis explores asexual spore submergence in rain, epiphytic development, the potential triggers for pycnidiation, low-nutrient ex planta survival, and soil treatments as a novel method of control. Novel findings include that (i) submergence leads to a form of spore dormancy, (ii) epiphytic development is more extensive than previously thought with hyphal growth and sporulation both occurring readily over a 21 day period, (iii) pycnidiation is a rapid, deterministic developmental process, triggered by contents of lysed plant cells, (iv) asexual spores have the capacity to survive for many weeks in low-nutrient environments, and finally (v) that treating soil-borne environmental spores may be a novel way to reduce field inoculum levels before a new crop is sown. Collectively these results provide many new insights in to the behaviour of Z. tritici during its disease cycle. This thesis proposes an updated version of the life cycle for this devastating fungal pathogen and argues that current methods of control are not adequate long-term.
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Kramer, Bastian. "Identifizierung und Charakterisierung neuer Pathogenitätsfaktoren in einem MAPK-Signalweg des weizenpathogenen Pilzes Mycosphaerella graminicola". Duisburg Köln WiKu, 2009. http://d-nb.info/992415756/04.
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LE, BOULC'H DELETRE VERONIQUE. "Evolution de la resistance a l'oidium (erysiphe graminis f. Sp. Tritici) dans des populations composites de ble tendre (triticum aestivum l. ) menees en gestion dynamique". Paris 11, 1994. http://www.theses.fr/1994PA112434.
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Dans le cadre d'un programme de gestion dynamique des ressources genetiques, mene en france sur le ble tendre depuis 1984, les populations de deux pools genetiques preferentiellement autogames et d'un pool conduit en allogamie sont multipliees chaque annee dans un reseau multilocal, essentiellement sous l'influence du milieu naturel. Au cours des huit annees de multiplication, les genes de resistance presents dans les populations composites initiales se sont maintenus. Les evolutions des frequences des genes de resistance specifique et de la resistance adulte mesuree au champ ont ete principalement conditionnees par le contexte genetique initial, mais des divergences sont apparues entre des populations multipliees sur des sites differents. Les populations allogames ont connu des evolutions plus marquees que les populations autogames et des combinaisons complexes de genes de resistance specifique y ont ete detectees. Les genes de resistance specifique dont la frequence a augmente dans les populations composites sont des genes surmontes par les populations pathogenes locales. Cependant, une relation positive entre resistance specifique et resistance adulte indique que les genes de resistance specifique identifies contribuent a la resistance adulte observee au champ. Un effet residuel des resistances contournees, ainsi qu'un effet de la structure des populations composites, analogue a celui des melanges varietaux, sont les hypotheses avancees pour expliquer la resistance apportee par ces genes. L'efficacite de la gestion dynamique, telle qu'elle est menee sur le ble, a ete confirmee pour la resistance a l'oidium, et la relation avec la selection doit etre envisagee. Les populations composites pourraient etre un moyen de selectionner en vue d'une aptitude au melange
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Schweizer, Patrick. "Induced local resistance of winter wheat (Triticum aestivum L.) to Erysiphe graminis f. sp. tritici : cDNA cloning and in vitro transcription of induced wheat mRNA /". [S.l : s.n.], 1988. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Tayeh, Christine. "Induction de résistances chez le blé (Triticum aestivum L.) lors d’une interaction compatible avec Blumeria graminis (DC. E.O Speer) : mécanismes mis en jeu après applications de tréhalose et d’heptanoyl d’acide licylique, dérivé fonctionnalisé de l’acide salicylique". Electronic Thesis or Diss., Littoral, 2012. http://www.theses.fr/2012DUNK0521.
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L’utilisation de molécules stimulatrices des défenses des plantes (SDP), également appelées inducteurs de résistance, constitue une alternative potentielle aux traitements fongicides conventionnels pour combattre les maladies dues à des champignons phytopathogènes. Trois SDPs, le tréhalose (TR), l’acide salicylique (SA) et l’heptanoyl d’acide salicylique (HSA), un dérivé fonctionnel du SA, protègent le blé (Triticum aestivum L.) contre l’oïdium (Blumeria graminis f.sp. tritici), lorsqu’ils sont utilisés de façon préventive. La protection obtenue n’est pas liée à un effet fongistatique direct sur la germination des spores du champignon, mais à l’induction chez le blé de défenses qui diminuent le développement de la maladie. Notre travail consistait à caractériser les mécanismes de défense mis en jeu après applications foliaires de TR, de HSA et de SA chez un cultivar de blé sensible à l’oïdium. Un suivi de l’expression de gènes marqueurs de défense, réalisé par RTqPCR, a été mené en cinétique,depuis le traitement par les SDPs jusqu'à 4 jours après infection. Les activités enzymatiques correspondantes ont été également mesurées, et l’influence indirecte des SPDs sur le processus infectieux a été observé en microscopie in planta. Ainsi, les réactions de défense déclenchées par le TR, le SA et le HSA ralentissent l’évolution de l’infection, jouant respectivement sur la germination des conidies, structures infectieuses de Bgt, sur la germination du tube germinatif appressorial (AGT) et sur la proportion d’AGTs qui parviennent à pénétrer dans les tissus foliaires. Le TR est à l’origine d’une augmentation de l’expression des gènes codant pour une lipoxygénase, une protéine de transfert des lipides et une phospholipase C, impliquées dans le métabolisme lipidique et la signalisation, et de gènes codant pour des protéines PR comme les chitinases et PR1, tous connus comme marqueurs de défense. Ainsi, les réactions déclenchées par le TR correspondent à un effet inducteur de défenseplutôt qu’à une réaction de stress osmotique. Le HSA modifie particulièrement le métabolisme lipidique, en induisant fortement et pendant toute la cinétique, l’expression du gène codant pour la LOX et l’activité correspondante, aussi bien hors contexte infectieux qu’en contexte infectieux. Cette augmentation de l’activité LOX n’est pas retrouvée chez des feuilles traitées au SA et caractérise donc le HSA. L’importance des réactions observées avec le TR, le SA et le HSA, hors contexte infectieux et en présence de Bgt amène à discuter les effets éliciteurs et potentialisateurs de ces 3 SDPsThe use of plant elicitors, also known as resistance inducers, is an alternative to conventional fungicides to control diseases caused by phytopathogenic fungi. Three resistance inducers, trehalose (TR), salicylic acid (SA) and heptanoyl salicylic acid (HSA), a functional derivative of SA, protect wheat (Triticum aestivum L.) against powdery mildew (Blumeria graminis f . sp. tritici) when applied prior to infection. The protection obtained is not linked to any direct fungistatic effect on the fungal spore germination, but to the induction of wheat defences that impair the development of the disease. Our work aimed at characterizing the defence mechanisms triggered after foliar applications of TR, HSA and SA in a wheat cultivar susceptible to powdery mildew. Monitoring of defence markers genes expression by RTqPCR was conducted during a time-course experiment from the treatment time until 4 days after infection. Corresponding enzyme activities were also measured, and the indirect influence of elicitors on the infectious process was observed by microscopy in planta. Thus, defence responses triggered by TR, SA and HSA slow the progression of the infection, respectively altering the germination of infectious structures such as conidia, the differentiation of appressorial germ tube (AGT) and the proportion of AGTs that manage to penetrate the epidermis. TR causes an increase in the expression of genes encoding a lipoxygenase, a lipid transfer protein and a phospholipase C, which are involved in lipid metabolism and signaling, and genes encoding for PR-proteins such as chitinases and PR1, all known as markers of defence. Thus, the reactions triggered by TR match with the ones triggered during induced defence rather than during osmotic stress response. HSA specifically targeted lipid metabolism, inducing strongly and throughout the time-course, the expression ofthe gene encoding LOX and the corresponding enzyme activity, both in infectious and non-infectious contexts. This increase in LOX activity was not found in leaves treated with SA and thus characterizes HSA mode of action. The importance of the reactions observed with TR, SA and HSA, in non-infectious conditions and in the presence of Bgt have to be considered regarding either elicitation or potentiation