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1
Kertho, Albert Okaba. "Evaluation of Winter Wheat Germplasm for Resistance to Stripe Rust and Leaf Rust." Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27571.
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Wheat leaf rust, caused by Puccinia triticina (Pt), and wheat stripe rust caused by P. striiformis f. sp. tritici (Pst) are important foliar diseases of wheat (Triticum aestivum L.) worldwide. Breeding for disease resistance is the preferred strategy of managing both diseases. The continued emergence of new races of Pt and Pst requires a constant search for new sources of resistance. Winter wheat accessions were evaluated at seedling stage in the greenhouse with races of Pt and Pst that are predominant in the North Central US. Association mapping approach was performed on landrace accessions to identify new or underutilized sources of resistance to Pt and Pst. The majority of the accessions were susceptible to all the five races of Pt and one race of Pst. Association mapping studies identified 29 and two SNP markers associated with seedling resistance to leaf rust and stripe rust, respectively.
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Kandiah, Pakeerathan. "Characterisation and molecular mapping of leaf rust and stripe rust resistance in wheat." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/16915.
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This investigation was carried out for the characterisation and chromosomal locations of resistance to rust diseases in common wheat and durum wheat recombinant inbred line (RIL) populations. A new seedling stripe rust resistance gene (tentatively named YrAW10) was identified in common wheat landrace Aus27696. This gene is effective against both pre-2002 and post-2002 Australian Puccinia striiformis f. sp. tritici (Pst) pathotypes. YrAW10 was located in 3BL-A02-FL-0.22 deletion bin of chromosome 3B and was flanked by SNP markers KASP_13376 and KASP_8775. Yr29/Lr46-linked marker SNPLr46G22 indicated the presence of this gene in Aus27696. The presence of Lr16 was confirmed on the basis of infection type produced by Aus91433 and controls (Thatcher + Lr16 and Exchange) against Puccinia triticina (Pt) pathotype 104-1,3,4,6,7,8,9,10,12+Lr37 and linked marker location in the short arm of chromosome 2B. Lr16 was not effective against the Pt pathotypes used in field study. Genotype C16.14 was proved to carry at least two adult plant resistance (APR) genes located on chromosomes 1D and 3B through iSelect 90K SNP based selective genotyping of C16.14/Aus91433 RILs. The chromosome 3B located resistance was proved to be Lr74 through genotyping of markers closely linked with this gene. In addition to Yr29/Lr46, two other consistent QTL for stripe resistance were detected in Arrivato/Bansi RIL population through DArTseq mapping. QYr.sun-1BS.1 corresponded to Yr24 and QYr.sun-1BS.2 was temporarily named YrAr. Both of these genes produced intermediate responses when present alone. Two QTL located on different linkage groups of chromosome 2B were identified in addition to Lr46/Yr29. QLr.sun-2B.1 appeared to be either a new gene or an allele of Lr16. Aus27506 was shown to carry QLr.sun-2D in addition to Lr46 and QLr.sun-2B was contributed by Aus27229 in Aus27506/Aus27229 population. QLr.sun-2D and QLr.sun-2B appears to be new loci. Comparison of chitin accumulation in the flag leaves with the performance of QTL indicated that combination of two QTL prevent the fungal growth resulting in low disease severity.
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Wondimu, Meseret. "Coffee leaf rust : epidemiology and management in Ethiopia." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338806.
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Mammadov, Jafar. "Towards Cloning the Leaf Rust Resistance Gene Rph5." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/28704.
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Leaf rust caused by Puccinia hordei is an important disease of barley (Hordeum vulgare) in many regions of the world. Yield losses up to 62% have been reported in susceptible cultivars. The Rph5 gene confers resistance to the most prevalent races (8 and 30) of barley leaf rust in the United States. Therefore, the molecular mapping of Rph5 is of great interest. Genetic studies were performed by analysis of 93 and 91 F2 plants derived from the crosses 'Bowman' (rph5) x 'Magnif 102' (Rph5) and 'Moore' (rph5) x Virginia 92-42-46 (Rph5), respectively. Linkage analysis positioned the Rph5 locus to the extreme telomeric region of the short arm of barley chromosome 3H at 0.2 cM proximal to RFLP marker VT1 and 0.5 cM distal from RFLP marker C970 in the Bowman x Magnif 102 population. Synteny between rice chromosome 1 and barley chromosome 3 was employed to saturate the region within the sub-centimorgan region around Rph5 using sequence-tagged site (STS) markers that were developed based on barley expressed sequence tags (ESTs) syntenic to the phage (P1)-derived artificial chromosome (PAC) clones comprising distal region of the rice chromosome 1S. Five rice PAC clones were used as queries to blastn 370,258 barley ESTs. Ninety four non-redundant EST sequences were identified from the EST database and used as templates to design 174 pairs of primer combinations. As a result, 10 EST-based STS markers were incorporated into the 'Bowman' x 'Magnif 102' high-resolution map of the Rph5 region. More importantly, six markers, including five EST-derived STS sequences, co-segregate with Rph5. Genes, represented by these markers, are putative candidates for Rph5. Results of this study demonstrate the usefulness of rice genomic resources for efficient deployment of barley EST resources for marker saturation of targeted barley genomic region.<br>Ph. D.
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Zwonitzer, John C. "Identification and mapping of a resistance gene to barley leaf rust(Puccinia hordei G. Otth)." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/36494.
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<p> Barley leaf rust (<I>Puccinia hordei</I> G. Otth) has been the cause of numerous and often devastating disease epidemics since the beginning of agriculture. Leaf rust is one of the most important diseases that affect barley (<I>Hordeum vulgare</I> L.) throughout the world. The pathogen <I>Puccinia hordei</I> is an obligate parasite. Symptoms of barley leaf rust may range from small chlorotic flecks to large pustules containing spores. Leaf rust epidemics reduce yields and grain quality.</p>
<p>Deployment of resistant cultivars is one of the most effective and economical means of controlling barley leaf rust. Identification and incorporation of new and effective sources of resistance are crucial to the success of barley breeding programs. Two types of resistance have been identified. They are race-specific resistance and partial resistance. A hypersensitive reaction by the host to infection of <I>P. hordei</I> isolates lacking corresponding virulence genes is indicative of race-specific resistance that is controlled by major genes. Sixteen race-specific genes (R<I>ph</I>1 to R<I>ph</I>16) have been identified. Partial resistance is generally polygenic and is often more durable that race-specific resistance.</p>
<p>The purpose of this research is to determine the inheritance of resistance to leaf rust in the barley experimental line VA 92-42-46, to identify the gene(s) conferring resistance, identify putative resistance related markers, and to map the gene(s) to one or more barley chromosomes using molecular markers. The Virginia barley line 92-42-46 was selected for this research project because it possesses resistance to <I>P. hordei</I> race 30, which has overcome resistance conferred by R<I>ph</I>7. Crosses were made between VA 92-42-46 and Moore, a susceptible cultivar to leaf rust. Inheritance studies were performed by screening F<sub>2</sub> progeny and F<sub>2:3</sub> families against race 8 and race 30 to determine the number of leaf rust resistance genes in VA 92-42-46. Allelism tests were performed to determine gene identity. A single dominant gene at the R<I>ph</I>5 locus or a tightly linked gene confers the resistance to P. hordei in VA 92-42-46. </p>
<p>Two populations, 'Moore' X VA 92-42-46 and 'Bowman' X 'Magnif', were used in this study for mapping molecular markers to provide comparison and confirmation of results. 'Magnif' possesses the resistance gene R<I>ph</I>5. Bulked segregant analysis was used to identify polymorphic RFLP and SSR markers that were used for mapping in each population. Linkage analysis revealed that the R<I>ph</I>5 gene maps to barley chromosome 3 (3H) above the centromeric region in the 'Moore' X VA 92-42-46 population. These findings agree with previous research that identified linkage between R<I>ph</I>5 and R<I>ph</I>7 on chromosome 3. The results obtained in this study do not support previous research that had reported the resistance gene R<I>ph</I>5 was located on barley chromosome 7 (5H). Further research should be conducted to verify the results of this study using the 'Bowman' X 'Magnif' population. The markers screened in the region above the centromere region of barley chromosome 3 were monomorphic for the 'Bowman' X 'Magnif' population except for the marker MWG561. Therefore, additional markers above the centromere of barley chromosome 3 should be screened.</p><br>Master of Science
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Grabow, Bethany. "Environmental conditions associated with stripe rust and leaf rust epidemics in Kansas winter wheat." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32835.
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Doctor of Philosophy<br>Department of Plant Pathology<br>Erick D. DeWolf<br>Stripe rust (caused by Puccinia striiformis f. sp. tritici) and leaf rust (caused by Puccinia triticina) are the top two diseases of winter wheat (Triticum aestivum) with a 20-year average yield loss of 4.9% in Kansas. Due to the significant yield losses caused by these diseases, the overall objective of this research was to identify environmental variables that favor stripe and leaf rust epidemics. The first objective was to verify the environmental conditions that favor P. triticina infections in an outdoor field environment. Wheat was inoculated with P. triticina and exposed to ambient weather conditions for 16 hours. Number of hours with temperature between 5 to 25°C and relative humidity >87% were highly correlated and predicted leaf rust infections with 89% accuracy. The results of this outdoor assay were used to develop variables to evaluate the association of environment with regional leaf rust epidemics.
Before regional disease models can be developed for a forecast system, suitable predictors need to be identified. Objectives two and three of this research were to identify environmental variables associated with leaf rust and stripe rust epidemics and to evaluate these predictors in models. Mean yield loss on susceptible varieties was estimated for nine Kansas crop reporting districts (CRD’s). Monthly environmental variables were evaluated for association with stripe rust epidemics (>1% yield loss), leaf rust epidemics (>1% yield loss), severe stripe rust epidemics (>14% yield loss) and severe leaf rust epidemics (>7% yield loss) at the CRD scale. Stripe rust and leaf rust epidemics were both strongly associated with soil moisture conditions; however, the timing differed between these diseases. Stripe rust epidemics were associated with soil moisture in fall and winter, and leaf rust epidemics during winter and spring. Severe stripe rust and leaf rust epidemics were associated with favorable temperature (7 to 12°C) and temperature (15 to 20°C) with relative humidity (>87%) or precipitation in May using tree-based methods of classification, respectively. The preliminary models developed in this research could be coupled with disease observations and varietal resistance information to advise growers about the need for foliar fungicides against these rusts in Kansas winter wheat.
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Nsabiyera, Vallence. "Genetic analysis and development of molecular markers linked with rust resistance in wheat." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17847.
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The main aim of this study was to develop closely linked markers for rust resistance genes Lr48, Lr49 and Sr48. In addition, mapping of adult plant stripe rust resistance in a landrace Aus27284 was also performed. Close SNP-Lr48 associations were identified using the iSelect 90K Infinium Array. Five SNP markers co-segregated with Lr48 and IWB70147 mapped 0.3 cM proximal. Kompetitive allele-specific PCR (KASP) assays were developed for linked SNP. In contrast, the KASP markers developed from the iSelect 90K Infinium SNP array for Lr49 did not result in close marker-trait association. Sequence comparison of flow sorted chromosome 4B from parents VL404 (Lr49) and WL711 (lr49) resulted in close association of sunKASP_21 (0.4 cM) with Lr49. The Arina/Cezanne RIL population was used to develop markers linked with Sr48 using the DArTseq platform and the iSelect 90K Infinium SNP Array. DArTseq based linkage map located Sr48 on the short arm of chromosome 2D. Marker sun590 derived from a DArTseq marker mapped 0.4 cM distal to Sr48. Sr48 was earlier mapped in the long arm of chromosome 2A in the Arina/Forno RIL population based on repulsion linkage with Yr1. The detection of 2AL-2DS translocation in Forno through genomic in-situ hybridisation (GISH) appears to have resulted in pseudo-linkage to locate Sr48 in chromosome 2AL. Aus27284 was susceptible to stripe rust at the seedling stage and exhibited resistance in field experiments. Genetic analysis showed monogenic segregation and the resistance gene was temporarily designated YrAW11. YrAW11 was located on chromosome 3BS near the centromere and KASP¬_65624/KASP_58449 and KASP_53113 flanked this locus. The closely linked markers identified in this study were tested on a set of Australian and Nordic wheat genotypes to validate their suitability for marker assisted selection (MAS). The results indicated that IWB70147, sunKASP_21, sun590 and KASP-53113 can be used for MAS of Lr48, Lr49, Sr48 and YrAW11, respectively.
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So, Yoon-Sup. "Corn leaf aphid and polysora rust resistance in tropical maize." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/7012.
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This research includes two separate studies both of which incorporated generation mean analyses to interpret genetically the resistance to com leaf aphid and polysora rust in tropical maize. The first study focused on resistance to corn leaf aphid in tropical sweet corn inbred Hi38-71. An inoculation technique using hair-pin clip cages and infestation quantification method using digital image analysis were developed for this study. During the study, a heavy natural infestation of com leaf aphids occurred in a seed production nursery. Yield loss by ranged from 38.9% to 98.8%, with an average loss of 71.7%. The clip-cage method was effective in distinguishing resistant and susceptible plants under field conditions. Resistance to com leaf aphid from Hi38-71 appeared to be monogenic and recessive. Aphid reproduction and population growth were measured on four different genotypes of varying aphid tolerance. Aphids on Hi38-71 had poorest performance over all aspects of growth and reproduction examined. Difference in number of progenies produced and days to 50% mortality appeared to account for most of the difference observed in the genetic study. The second study estimated genetic parameters for polysora rust resistance in Hi38-71. Hi38-71 exhibited moderately high resistance to polysora rust as well as resistance to com leaf aphid. Generation mean analysis showed that epistatic interactions of [aa] and [dd] along with simple dominance and additive gene effects were involved in controlling resistance in Hi38-71 to polysora rust. It is concluded that polysora resistance breeding cannot be based on selection of a single parent but a hybrid-breeding or reciprocal recurrent selection approach appears justified. The tropical sweet corn inbred, Hi38-71 is a sib line of Hi38 which was bred from a bt-1 conversion of AA8sh2. AA8sh2 was studied for its resistance to corn leaf aphid in 1970's in Hawaii and was converted to common rust resistance, Rd1-D which broke down due to evolved racial variation of the pathogen. Hi38-71 is thus of particular value in sweet corn breeding for tropical regions. This is due not only to its resistance to corn leaf aphid and polysora, but to its high sweet corn qualities and generally good combining abilities.<br>xiii, 86 leaves
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Smith, Lauren M. "Mapping of drought tolerance and leaf rust resistance in wheat." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/799.
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DAKOURI, ABDULSALAM. "Genetic analysis of leaf rust resistance gene Lr34 in wheat." SpringerLink, 2010. http://hdl.handle.net/1993/13236.
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Effective at the adult plant stage, Lr34 is the most important resistance gene to leaf rust. Usage of closely linked molecular markers is the best strategy to facilitate the incorporation of economically important genes in an adapted plant germplasm. Ten novel molecular markers spanning the Lr34 locus were developed, including six microsatellites (cam), one insertion site-based polymorphism (caISBP), two single nucleotide polymorphisms (caSNP) and one indel marker (caIND). Marker caIND11 is the best diagnostic marker for marker assisted selection of Lr34. Two novel haplotypes of Lr34 were discovered in the germplasm. Analysis of these markers on five segregating populations revealed a recombination between caSNP4 and cam8 which provided further support for the identity of the ABC transporter as Lr34. Using Lr34-specific markers, the world collection (WC) was divided into five major haplotypes (H) of which H1 was consistently associated with the resistance phenotype Lr34+. SNP12-C is the functional unit of Lr34. Maximum parsimony network and other observations revealed that H4, an Lr34- haplotype, was probably the most ancient haplotype and H1 the most recent and that it likely arose after the advent of hexaploid wheat. Analysis of geographical distribution showed that H1 was at a high frequency in the Asian germplasm while H4 was more frequent in the European germplasm. Lr34, a gain of function mutation, was hypothesized to have originated in Asia. The (WC) was characterized for seedling and adult plant resistance using gene specific markers and gene postulation. Fourteen seedling genes were determined or postulated in the collection. Lr1, Lr10, Lr3 and Lr20 were the most highly represented genes while Lr9, Lr14b, Lr3ka and/or Lr30 and Lr26 were rare. The WC was evaluated for field resistance. The rust rating in the field ranged from nearly immune (1R) to highly susceptible (84S). Most Lr34 containing accessions had maximum rust severity (MRS) of 35%. The high levels of resistance in some accessions are likely the result of synergy between APR genes or between APR and seedling genes. Accessions that were highly resistant should be considered potential sources of resistance for future wheat breeding program to improve leaf rust resistance.
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Mehnaz. "Genetic and molecular characterization of leaf rust resistance in barley." Thesis, The University of Sydney, 2020. https://hdl.handle.net/2123/27511.
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Cereal crops play a vital role in global food security. Barley is the fourth most important cereal crop globally and second to wheat in Australia with important uses as animal feed, raw material for brewing malt and human food. Rust pathogens significantly reduce yield and production of barley. Barley leaf rust (BLR) is the most prevalent foliar fungal disease, which can be best managed through genetic resistance. This research focuses on various components of genetic resistance for controlling BLR and highlights the exploitation of untapped genetic diversity of H. spontaneum in finding new sources of resistance. Furthermore, it also elaborates the use of various latest genomic resources that can be utilized to underpin the mechanism of resistance against BLR.
This dissertation provides detailed insight to the genetics of resistance of BLR. Chapter 1 starts with general introduction about BLR and its global status as well as its importance in Australia. Chapter 2 comprises a detailed review of the literature on BLR, dissecting various components of resistance, old vs new technologies for genetic mapping and gaps in previous studies. Chapter 3 of this thesis provides detail about “Discovery and fine mapping of Rph28: a new gene conferring resistance to Puccinia hordei from wild barley”. Chapter 4 focused on “Characterization of leaf rust resistance in a panel of international barley germplasm from Middle East and Central Asia sourced from Australian Grain Gene Bank (AGG)” to identify new sources of resistance. In Chapter 5, the development of mapping populations from selected AGG-lines, identification of genomic regions for BLR in these populations and fine mapping of underlying resistance (RphAGG396) in one of these populations is discussed in detail. Chapter six of this thesis comprises general discussion and recommendations based on outcomes of research findings.
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Oliveira, Cleber Macedo de. "Interactions of Ricoseius loxocheles (Acari: Phytoseiidae) and coffee leaf rust." Universidade Federal de Viçosa, 2012. http://locus.ufv.br/handle/123456789/3951.
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Previous issue date: 2012-07-12<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>O cafeeiro apresenta perdas econômicas devido a pragas e doenças. Entre as pragas, os ácaros fitófagos merecem atenção devido à redução da área fotossintética. Além dos danos dos ácaros, alguns patógenos também atacam plantas de café como a ferrugem-do-cafeeiro, Hemileia vastatrix (Uredinales). Este patógeno causa perdas de produtividade de 30% em algumas variedades de Coffea arabica. Ácaros da família Phytoseiidae normalmente controlam populações de ácaros fitófagos e podem desenvolver-se e reproduzirem usando diversas fontes alimentares, além dos ácaros presa. Dentro da família Phytoseiidae, que é composto por ácaros carnívoros e os que se alimentam de pólen, em levantamentos foi encontrado a espécie Ricoseius loxocheles (De Leon) (Acari: Phytoseiidae) sobre áreas de necrose causada pela ferrugem do cafeeiro, durante sua fase reprodutiva. Existem poucas informações sobre o seu desenvolvimento, parâmetros biológicos e hábitos alimentares. Avaliou-se a taxonomia, desenvolvimento, parâmetros de sobrevivência e reprodução de R. loxocheles alimentando-se de urediosporos da ferrugem do cafeeiro e sua capacidade predatória e sucesso reprodutivo sobre Oligonychus ilicis (McGregor, 1971). Uredosporos da ferrugem-do-cafeeiro apoiaram a sobrevivência, desenvolvimento e reprodução do ácaro fitoseídeo estudado e este não foi capaz de predar O. ilicis. A sobrevivência e oviposição de R. loxocheles só foi observada quando este ácaro alimentou-se de ferrugem. Em arenas sem o fungo esses parâmetros foram iguais as arenas sem alimento. A reprodução tem a exigência nutricional mais elevada do que o desenvolvimento. R. loxocheles alimentados com ferrugem obteve parâmetros reprodutivos mais elevados do que outros fitoseídeos alimentados em outros fungos, alguns ácaros ou pólen. Conclui-se que este ácaro é um fitoseídeo generalista e são necessários mais estudos para medir a capacidade de alimentarem-se em outras fontes alimentares, tais como ácaros fitófagos pragas do cafeeiro. É possível que R. loxocheles tenha um papel no controle da ferrugem do cafeeiro, uma vez que se alimenta de uma grande quantidade de uredosporos da ferrugem.<br>Coffee crops have economic losses due pests and diseases. Among them, the phytophagous mites deserve attention due to the reducing photosynthetic area caused on the leaves. Besides of mite damages, some pathogens also attack coffee plants, as the coffee rust fungus, Hemileia vastatrix (Uredinales). This pathogen cause yield losses around 30% in some varieties of Coffea arabica. Predatory mites from the Phytoseiidae family normally control phytophagous mites and can develop and reproduce using various alternative food sources than their primary prey, tetranychid mites. Within the Phytoseiidae family that is composed by carnivorous and pollen-feeding mites, we surveyed in the field the species Ricoseius loxocheles (De Leon) (Acari: Phytoseiidae) on the necrosis area caused by coffee rust during its reproductive phase. Searching in the literature showed that there is little information related to this mite development, biological parameters and feeding habits. So, this study was carried out to assess the taxonomy, development, survivorship and reproduction parameters of R. loxocheles feeding on coffee rust fungus, its predation capacity on Oligonychus ilicis (McGregor, 1971) and its reproductive success. Coffee rust supported the survival, development and reproduction of the phytoseiid mite and that it was not able to feed on different stages of O. ilicis. Survival and oviposition of R. loxocheles was only observed when this mite was in arenas with fungi. In arenas without fungi these parameters were equal as arenas without food. It is known that reproduction has a higher nutritional requirement than development. The fertility of R. loxocheles fed on coffee rust is highest that the other phytoseiid fed in others fungi or some mites or pollen. We suggest that this mite is a phytoseiid generalist and it is necessary more studies to measure the ability of this mite specie to feed on other food sources, such as herbivore mites pests of coffee crops. It is possible that R. loxocheles has a role in the control of coffee rust since it feeds on a large amount of rust uredospore.
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Hung, Hsiao-Yi. "Characterization of a gene from breeding line WX93D180 conferring resistance to leaf rust (Puccinia triticina) in wheat." Texas A&M University, 2007. http://hdl.handle.net/1969.1/85877.
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Wheat (Triticum aestivum L. em. Thell, 2n=6x=42, AABBDD) is subjected to
significant yield losses by the endemic leaf rust pathogen, Puccinia triticina (Roberge ex
Desmaz. F. sp. tritici). Breeding for resistance to this disease is a more appropriate
option both environmentally and economically over fungicidal application. More than 57
leaf rust resistance genes in wheat have been identified and many of the resistance genes
have been successfully introgressed into resistant cultivars, yet the continuous shifting of
predominant races of P. triticina continues to be a challenge to breeders. Pyramiding
multiple resistance genes into a single resistant cultivar is one of the preferred strategies
to develop superior disease resistant cultivars. Efficient pyramiding requires the
utilization of markers closely linked to the resistance genes. The objectives of this study
were to characterize a novel source of resistance to leaf rust introgressed into the
breeding line WX93D180-R-8-1, to determine its inheritance, map position, and linkage
with molecular markers suitable for marker assisted selection. According to the pedigree
of WX93D180, TX86D1310*3/TTCC417, the resistance in this breeding line should be
derived from TTCC417 (Turkey tritici cereal collection), which was thought to be Triticum monococcum, which is a diploid species made up of only the A genome.
However, our marker analyzes results indicated the resistance gene is located in the D
genome and has the same location as the cloned leaf rust resistance gene Lr21. We
verified the result in our population using primers from Lr21 and found the same
segregation pattern with the phenotypic data (disease response). Therefore the pedigree
is incorrect, TTCC417 was misidentified, or the resistance was not from TTCC417.
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Neugebauer, Kerri Allison. "Identification of wheat genes induced by Puccinia triticina." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/34465.
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Doctor of Philosophy<br>Department of Plant Pathology<br>Harold N. Trick<br>Bread wheat (Triticum aestivum L.) is an important staple crop for 35% of the world’s population. One economically important pathogen of wheat is Puccinia triticina, the causal agent of leaf rust, can cause up to 50% yield loss during epidemics. Despite the lack of an alternate host to complete the sexual stages, P. triticina still has variation within the population, which can make achieving durable resistance difficult. This study aims to gain a better understanding of the P. triticina-wheat interaction by identifying wheat genes that are induced by individual and multiple races. Six P. triticina races were evaluated on a susceptible variety of wheat at six days post inoculation. RNA was sequenced and 63 wheat genes were identified that showed varying expression in response to the six P. triticina races. Fifty-four wheat genes were characterized during the first seven days of infection using real-time PCR. Race specific gene expression was found in three wheat genes with race differences on Lr2A, Lr2C, and Lr17A. Wheat genes that had similar expression in response to all six races were also identified. Seven of the characterized genes were then silenced using RNAi hairpin constructs. The transgenic plants were molecularly characterized and inoculated with a virulent P. triticina race in the T₂ generation. However, the endogenous genes were not silenced and the transgenic plants maintained susceptibility. A mutation approach was also used to identify wheat genes involved in infection. A mutant population of 3780 wheat plants was created using EMS. Fifteen hundred mutants from the M1 population were screened for plants with a different infection phenotype compared to the non-mutated control and 570 were selected. After two additional generations of selection, eight resistant mutants were obtained. The gene expression of the seven previously identified genes were evaluated and one mutant showed reduced expression of an ER molecular chaperone gene. This research uses a forward and reverse genetics approach to identify and evaluate the function of wheat genes in the wheat-P. triticina interaction. Although RNAi could not determine the gene function, the knockout mutant shows that the identified genes may have a crucial role in infection.
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Johansson, Leif. "Resistance in Salix against willow leaf rust caused by Melampsora epitea /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5741-6.pdf.
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Dinh, Xuan Hoan. "Molecular genetics of barley (Hordeum vulgare): Leaf rust (Puccinia hordei) interactions." Thesis, The University of Sydney, 2020. https://hdl.handle.net/2123/24567.
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Leaf rust caused by Puccinia hordei is one of the most common and widely distributed rust diseases of barley. Deploying genetic resistance is considered as the most effective and environmentally friendly approach to control this disease. Among 27 designated loci conferring resistance to P. hordei, three genes, namely Rph1, Rph15, and Rph22, have been previously isolated. In this study, the Rph3 gene was isolated using the positional cloning approach. A high-resolution map of the gene constructed using 10,411 F2 plants from six segregating populations delimited the Rph3 locus between two markers covering an interval of 0.024 cM. The physical map revealed that these two closest markers delimited a region of 8.5kb bp in Rph3-carrying cultivars such as cv. Barke and 98kb bp in cultivars lacking Rph3 such as cv. Morex. Two putative genes were determined within the 8.5kb region using FGENESH. The candidate gene for Rph3 was validated by mutational analysis, where four independent point mutations confirmed that ORF2 is Rph3. The resistance gene Rph3 encodes a protein of unknown function that does not belong to any known plant disease resistance protein family. The amino acid sequence showed no sequence homology to any domains/motifs of known function. Predictions using various tools revealed five to seven transmembrane helices in the structure of RPH3. Gene expression was locally induced at the infection site by pathotypes avirulent for Rph3. The current results suggest that the Rph3 gene acts like an executor gene that is regulated by transcriptional activator-like (TAL) effectors. A second study determined that resistance to P. hordei pathotype 5477 P- in the barley line 67:ZBS15 was conferred by two genes interacting in a complementary manner. One of these two genes is Rph3 and the other one was supposed to be Rph5 or an allele of Rph5 or an independent locus in the same genomic region as that of Rph5.
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Abdul, Suleiman Dangana. "Brown rust of wheat : temperature sensitivity, genetic analysis and pathogen variation." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321534.
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Samils, Berit. "Population genetic structure of Melampsora larici-epitea, a willow leaf rust fungus /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5844-7.pdf.
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Sun, Xiaochun. "Genetic characterization of wheat genes resistance to tan spot and leaf rust." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1606.
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Helfer, Stephan. "Characteristics of leaf rust fungi of temperate cereals and their host relationships." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/28219.
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This thesis describes work carried out mainly on the uredinial stage of the leaf rust fungi of temperate cereals, comprising the brown rusts of barley, rye and wheat as well as oat crown rust and the wheat and barley yellow rusts. The taxonomic position of these pathogens was investigated in colony growth studies carried out under controlled conditions, with an emphasis on characters which were independant of cereal host factors. A clear morphological distinction could be made between oat crown rust, wheat brown rust, barley brown rust, rye brown rust and the yellow rusts of wheat and barley. However, no distinction apart from the host range could be made between wheat and barley yellow rust. In culture experiments the isolates were tested for their ability to grow on detached leaves of their host plants, and some of the isolates were used in axenic culture studies. All the isolates showed identical virulence patterns on detached leaves as on whole host plants. None of the isolates tested could be maintained in axenic culture. Cytogenetical characteristics were studied in some of the rust isolates. The dikaryotic binucleate condition prevailed in all isolates up to the stage of stomatal penetration. Attempts to obtain hybridisation between different races of wheat yellow rust failed. Quantitative aspects of colony growth and development were investigated in a series of studies in controlled conditions. Differences in response to inoculum density were observed in experiments with barley brown rust and yellow rust and were related to the different patterns of epidemic development of these two species. The colony growth patterns of the cereal leaf rusts in host and non-host relationships showed strong host preference. However, unexpected colony development occurred in some of the pathogen/non-host combinations.
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BARBIERI, MIRKO. "THE GENETICS OF LEAF RUST RESISTANCE IN THE MODEL GRASS BRACHYPODIUM DISTACHYON." Doctoral thesis, Università Cattolica del Sacro Cuore, 2009. http://hdl.handle.net/10280/640.
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Brachypodium distachyon è stato recentemente proposto come pianta modello per le Triticeae che includono frumento e orzo. L’obbiettivo del presente studio è stato quello di identificare regioni genomiche associate con la resistenza quantitativa alla ruggine fogliare in Brachypodium. Le malattie causate dalle ruggini fogliari causano ingenti perdite in termini di produzione delle specie cerealicole. Una popolazione di 110 individui F2 è stata sviluppata incrociando due linee inbred di Brachypodium e una mappa di linkage di marcatori AFLP è stata create. La mappa di linkage consiste di 192 loci AFLP in dieci gruppi di linkage, e copre una lunghezza pari a 1,231 Kosambi cM. Allo scopo di identificare loci coinvolti nella resistenza quantitativa sulla mappa, i 110 individui F2 sono stati valutati per la loro reazione alla ruggine fogliare allo stadio di plantula e a quello adulto. Per confermare i risultati delle piante F2, le rispettive famiglie F3 sono state studiate per la loro resistenza alla ruggine fogliare in due esperimenti indipendenti. Due loci genomici sembrano essere maggiormente coinvolti nella resistenza.<br>Brachypodium distachyon has been proposed as a model species for the tribe of the Triticeae, which includes wheat and barley. The objective of our study was to identify the genomic regions associated with quantitative resistance to leaf rust in Brachypodium. Leaf rust diseases cause significant reductions annually in yield of cereal crops worldwide. An F2 mapping population of 110 individuals was generated between two Brachypodium inbred lines and a AFLP-based linkage map was developed. The linkage map consists of 192 AFLP loci in ten linkage groups, and spans a total genetic length of 1,231 Kosambi cM. To locate quantitative resistance loci on the map, the 110 F2 plants were evaluated for their reaction to the leaf rust at both seedling and adult plant stages. To improve QTL identification, F2-derived F3 families were studied for resistance to leaf rust in two independent experiments. Two major genomic regions involved in resistance to leaf rust were detected.
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BARBIERI, MIRKO. "THE GENETICS OF LEAF RUST RESISTANCE IN THE MODEL GRASS BRACHYPODIUM DISTACHYON." Doctoral thesis, Università Cattolica del Sacro Cuore, 2009. http://hdl.handle.net/10280/640.
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Brachypodium distachyon è stato recentemente proposto come pianta modello per le Triticeae che includono frumento e orzo. L’obbiettivo del presente studio è stato quello di identificare regioni genomiche associate con la resistenza quantitativa alla ruggine fogliare in Brachypodium. Le malattie causate dalle ruggini fogliari causano ingenti perdite in termini di produzione delle specie cerealicole. Una popolazione di 110 individui F2 è stata sviluppata incrociando due linee inbred di Brachypodium e una mappa di linkage di marcatori AFLP è stata create. La mappa di linkage consiste di 192 loci AFLP in dieci gruppi di linkage, e copre una lunghezza pari a 1,231 Kosambi cM. Allo scopo di identificare loci coinvolti nella resistenza quantitativa sulla mappa, i 110 individui F2 sono stati valutati per la loro reazione alla ruggine fogliare allo stadio di plantula e a quello adulto. Per confermare i risultati delle piante F2, le rispettive famiglie F3 sono state studiate per la loro resistenza alla ruggine fogliare in due esperimenti indipendenti. Due loci genomici sembrano essere maggiormente coinvolti nella resistenza.<br>Brachypodium distachyon has been proposed as a model species for the tribe of the Triticeae, which includes wheat and barley. The objective of our study was to identify the genomic regions associated with quantitative resistance to leaf rust in Brachypodium. Leaf rust diseases cause significant reductions annually in yield of cereal crops worldwide. An F2 mapping population of 110 individuals was generated between two Brachypodium inbred lines and a AFLP-based linkage map was developed. The linkage map consists of 192 AFLP loci in ten linkage groups, and spans a total genetic length of 1,231 Kosambi cM. To locate quantitative resistance loci on the map, the 110 F2 plants were evaluated for their reaction to the leaf rust at both seedling and adult plant stages. To improve QTL identification, F2-derived F3 families were studied for resistance to leaf rust in two independent experiments. Two major genomic regions involved in resistance to leaf rust were detected.
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Nyori, Peter Michael Bulli. "Genetics of resistance to leaf and stripe rust diseases in the spring wheat 'Amadina'." Diss., Kansas State University, 2010. http://hdl.handle.net/2097/4611.
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Doctor of Philosophy<br>Department of Agronomy<br>Allan K. Fritz<br>In this research, a recombinant inbred line (RIL) population derived from cross between a leaf rust- and stripe rust-susceptible spring wheat ‘Avocet S’ and a slow leaf- and stripe-rusting resistant spring wheat ‘Amadina’ was used to postulate and map leaf rust seedling resistance genes, identify quantitative trait loci (QTL) for slow-rusting resistance against leaf and stripe rust, and study slow leaf-rusting components, latent period and infection frequency. Two known Lr genes (Lr23, and Lr26) were identified to be present in ‘Amadina’ through gene postulation, pedigree, cytogenetic, and polymerase chain reaction analyses. One unknown gene associated with seedling resistance was also mapped on chromosome 1BL. In greenhouse experiment, it was estimated that at least five genes conditioning final disease severity (FS) and latent period (LP), and four genes conditioning infection frequency (IF), segregated in the population. Correlations between LP and FS, and LP and IF were moderately negative, and that between IF and FS was moderately positive, indicating inter-dependence of the traits. Two QTL on chromosomes 1BL and 6BL were associated with LP and FS, and three QTL on chromosomes 1BL, 6BL and 2DS were associated with IF. Segregation of the RIL population in field experiment indicated that there were at least four and three adult plant resistance (APR) genes involved in resistance for leaf and stripe rust. Six QTL on chromosomes 3AL, 4AL, 1BL, 5BL, and 7BL were associated with APR for leaf rust, and seven QTL on chromosome 4AL, 5AL, 1BL, 2BL, 4BL, 5BL, 2DL, and 4D were associated with APR for stripe rust. Our results indicated that the major portion of genetic variability for slow-rusting resistance was additive gene action, and, to some extent, epistasis. In this research, we also explored the utility of remote sensing and geographic information systems (GIS) and analytical operations to discriminate leaf rust pustules from other parts of leaf and to accurately determine pustule size in ‘Amadina’ and ‘Avocet S’.
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Mwangi, Symon Munanda. "Status of Northen Leaf Blight, Phaeosphaeria maydis Leaf Spot, Southern Leaf Blight, Rust, Maize Streak Virus and Physiologic Specialization of Exserohilum turcicum in Kenya." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/26093.
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Exserohilum turcicum, Phaeosphaeria maydis, Bipolaris maydis, Puccinia polysora, Puccinia sorghi and maize streak virus were the most serious maize pathogens found in Kenya during a 1995/96 survey of 65 farms representing all the agro-ecological zones. Exserohilum turcicum - induced blight was observed in all maize producing areas with disease incidence reaching over 45%. Lesions were sometimes over 400 mm long by 25 mm in width. Southern leaf blight caused by Bipolaris maydis was most severe in the Kenyan maize granary located in the highlands west of the Rift Valley where it occurred alone or with Phaeosphaeria maydis leaf spot. Incidences of over 75% were recorded for southern leaf blight and Phaeosphaeria maydis leaf spot in western Kenya and over 85% for Phaeosphaeria maydis leaf spot in Thika, Nyeri, Muranga and Kirinyaga Districts of Central Province. Common rust caused by Puccinia sorghi was equally severe in the areas of Molo, Njoro and Bahati in Nakuru District with severity levels of over 65%. Lowland rust caused by Pucinia polysora was important in the coastal region with over 75% disease severity in Kwale District. Traces of lowland rust were observed in Kirinyaga District. Maize streak virus was severe in the Lake Victoria region of western Kenya, central areas of Kenya and in the Coast. This disease was severe where Napier grass (Pennisetum purpureum) with streak like symptoms was near the infected maize plots. Individual cultures of Exserohilum turcicum were not appreciably different in appearance but varied in growth rates at 22oC. A total of nineteen isolates of Exserohilum turcicum were classified into races using the Ht gene bearing maize differential inbred lines. Three isolates were race 0, three were race 1, one was race 2, one was race 3, two isolates were race 12, and eight did not fit in the known classification. These were named and grouped as k1, k2 and k3. The k3 race was virulent to HtN gene only. Four Kenyan and two American lines were inoculated with eight isolates of Exserohilum turcicum. All the Kenyan lines were susceptible to the isolates used. Tables of means comparisons and figures for disease occurrence and severity are provided. This is the first time disease prevalence and severity has been documented for maize in Kenya.<br>Ph. D.
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Herrera-Foessel, Sybil A. "Enhancing the genetic diversity and durability of leaf rust resistance in durum wheat /." Uppsala : Dept. of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200701.pdf.
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Ibrahim, Mohamed Somo. "Characterization of Common Wheat Translocations Carrying Leaf Rust Resistance Genes from Alien Species." Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25828.
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Leaf rust caused by Puccinia triticina Erikss may inflict significant yield losses in wheat; however, can be controlled by breeding for increased host resistance. In earlier studies, effective, resistance has been transferred to common wheat from the wild relatives Thinopyrum ponticum (Lr19), Aegilops sharonensis (Lr56), Ae. peregrina (Lr59), and Ae. neglecta (Lr62). Each translocation was subsequently re-engineered by the induction of homoeologous chromosome exchanges with a normal wheat chromosome to remove unneeded alien chromatin. For each gene the 3-8 most promising recombinants that retained the least linkage drag, but could not be differentiated, were identified. This study employed physical and genetic mapping in conjunction with molecular markers and genomic in situ hybridization to identify those recombinants that are best suited for breeding. For each gene, the recombinant with the least alien chromatin that also appeared to be fully compensating was identified and marker loci suitable for marker-assisted selection were suggested.<br>North Dakota Wheat Commission<br>Minnesota Wheat Research and Promotion Council
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Troskie, Christiaan. "Identification and characterisation of markers linked to the leaf rust resistance gene LR37." Diss., University of Pretoria, 2000. http://hdl.handle.net/2263/29076.
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Sun, Qun. "Genome-Wide Association Mapping of Host Resistance to Stem Rust, Leaf Rust, Tan Spot, and Septoria Nodorum Blotch in Cultivated Emmer Wheat." Diss., North Dakota State University, 2015. http://hdl.handle.net/10365/24881.
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Cultivated emmer wheat (Triticum turgidum ssp. dicoccum) is a good source of genes for resistance to several major diseases of wheat. The objectives of this study were to use genome-wide association analysis to detect genomic regions in cultivated emmer germplasm harboring novel resistance genes to four wheat diseases: stem rust, leaf rust, tan spot, and Septoria nodorum blotch (SNB). A natural population including 180 cultivated emmer accessions with a high level of geographic diversity was assembled as the association-mapping panel. This cultivated emmer panel was evaluated phenotypically by scoring reactions to stem rust, leaf rust, tan spot, and SNB and was genotyped using a 9K SNP Infinium array. After filtering for missing data points and minor allele frequency (MAF), 4,134 SNPs were used for association analysis using 178 emmer accessions. Based on principle component (PC) analysis, five subpopulations strongly associated with geographic origins were suggested by the first three PCs. Genome-wide association analysis revealed that 222, 42, 146, and 42 SNPs were significantly associated with resistance to stem rust, leaf rust, tan spot, and SNB, respectively, at the significant level of 1 percentile. Among the significant SNPs at the significant level of 0.1 percentile, ten, one, nine, and one co-located with known genes or QTL associated with resistance to the four diseases, respectively. The remaining significant SNPs were located in the genomic regions where no known resistance genes have been identified for the four diseases. This evidence suggests that some of the emmer wheat accessions carry novel genes conferring resistance to the four diseases. Additionally, 14, three, eight, and five LD blocks harboring at least one significant SNP were identified and might harbor putative QTL related to resistance to the four diseases, respectively. These studies provide information about the genomic regions in cultivated emmer that are associated with resistance to stem rust, leaf rust, tan spot, and SNB. Results from these studies provide guidance for selecting emmer accessions when decisions are being made about the parents that will be used for the development of new resistant germplasm and mapping populations for identifying novel genes conferring resistance to major wheat diseases.<br>Chinese Scholarship Council (CSC)
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Aqeel, Abdullah Mohammad. "USING MANUAL DEFOLIATION TO SIMULATE SOYBEAN RUST: EFFECT ON GROWTH AND YIELD FORMATION." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/223.
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Field experiments were conducted in Kentucky and Louisiana in 2008 and 2009 (split-plot in a randomized complete block design with four replications) to investigate it is possible to simulate with manual defoliation the effect of soybean rust (SBR) (Phakopsora pachyrhizi Syd. and P. Syd) injury on a healthy soybean [Glycine max, (L.) Merr.] canopy, understand how defoliation affects the growth dynamics and canopy light interception, and if defoliation affectsleaf senescence and nitrogen remobilization during the seed-filling period. Two manual defoliation treatments based on changes in effective leaf area index (ELAI) (calculated as the reduction in leaf area equivalent to SBR-induced premature leaf abscission, loss in green leaf area, and reduction in photosynthetic capacity of diseased leaves) in infected canopies in Brazil were used to simulate SBR infection at growth stage R2 (full flowering) and R5 (beginning of seed-fill). Both defoliation treatments reduced yield in all experiments and the reduction was larger for the treatments at growth stage R2. The yield losses were equivalent to that observed in infected soybean canopies in Brazil. This suggests that a system of manual defoliation to simulate changes in effective leaf area duration shows promise as a tool to simulate the impact of SBR on soybean yield. The radiation use efficiency and crop growth rate from growth stage R2 to R5 were not influenced by defoliation. Defoliation started at growth stage R2 reduced seed number per unit area, while defoliation started at growth stage R5 reduced seed size due to shortening the seed-fill duration and a lower seed growth rate. There is no evidence that manual defoliation affected leaf senescence or nitrogen redistribution to the seed. This study found that the reduction of light interception by SBR was the main reason for the reductions in soybean growth and yield.
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Stirling, Brigid V. "Molecular characterization of major gene resistance in a populus-leaf rust pathosy[s]tem /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5512.
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Salmon, Lesley Anne. "The occurrence of races of rust and leaf spot pathogens of groundnut (Arachis hypogaea)." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46460.
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Huang, Li. "High-resolution mapping and molecular cloning of leaf rust resistance gene Lr21 in wheat /." Search for this dissertation online, 2002. http://wwwlib.umi.com/cr/ksu/main.
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Jesus, Junior Waldir Cintra de. "Effects of angular leaf spot and rust on plant growth and yield of Phaseolus vulgaris." Universidade Federal de Viçosa, 2001. http://www.locus.ufv.br/handle/123456789/11523.
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Previous issue date: 2001-03-09<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Este trabalho teve por objetivo estudar o efeito da mancha angular (Phaeoisariopsis griseola) e da ferrugem (Uromyces appendiculatus) sobre o crescimento e produção do feijoeiro (Phaseolus vulgaris).A tese foi organizada em cinco capítulos. Os dois primeiros capítulos foram escritos utilizando-se dados coletados a partir de 3 experimentos de campo, em que foram efetuadas diferentes análises. Os demais capítulos referem-se a resultados obtidos em experimentos independentes. Capítulo 1. No presente capítulo foram estudados os efeitos da mancha angular e da ferrugem, isoladas e conjuntas, sobre o crescimento (área abaixo da curva de progresso da área foliar, duração da área foliar sadia e absorção da área foliar sadia) e produção do feijoeiro. Em todos os experimentos não houve diferença estatística entre os tratamentos no tocante às variáveis área abaixo da curva de progresso da área foliar (AULAPC), duração da área foliar sadia (HAD) e absorção da área foliar sadia (HAA), entretanto todos os tratamentos inoculados diferiram do controle em severidade de doença e produção. Em geral, não obteve-se relação entre produção e doença, ao passo que a produção relacionou-se linearmente com as variáveis HAD e HAA. Concluiu-se que a mancha angular causa desfolha, enquanto que a ferrugem não afeta a área foliar. A ferrugem causou maior redução na produção se comparado à mancha angular, porém o decréscimo na fotossíntese causado pela mancha angular foi duas vezes maior. Capítulo 2. Neste capítulo foram investigados os efeitos da mancha angular e da ferrugem, isoladas e conjuntas, sobre a troca gasosa (taxa fotossintética líquida, condutância estomática e transpiração) do feijoeiro. A inoculação das plantas com P. griseola (tratamento P), U. appendiculatus (tratamento U) e com ambos patógenos (tratamento P+U) causou significante redução na taxa fotossintética líquida e na produção. Os tratamentos P e P+U resultaram em redução significativa da condutância estomática. A partir da análise dos dados foi observado que os efeitos das doenças sobre a produção podem ser explicados por decréscimos na condutância estomática e na taxa fotossintética líquida. Capítulo 3. No referido capítulo foram analisadas as relações entre mancha angular, área foliar sadia, área foliar efetiva e produção do feijoeiro. Não foi observada relação entre severidade visual ou virtual e produção, entretanto relação linear positiva foi obtida entre as variáveis duração da área foliar sadia (HAD), absorção da área foliar sadia (HAA), duração da área foliar efetiva (ELAD), absorção da área foliar efetiva (ELAA) e produção. Foi observado constância nos valores de inclinação (coeficiente angular), obtidos a partir da regressão linear entre produção e índice de área foliar sadio (HLAI), independentemente da data de plantio e estádio de crescimento do feijoeiro (de R6 a R8). HLAI é proposta como variável explanatória para um sistema transportável de manejo da doença, possibilitando recomendações precisas em nível de produtor. Capítulo 4. Neste capítulo foram avaliadas estraté gias de manejo da mancha angular do feijoeiro baseadas em aplicação de molibdênio e controle químico. Foi observado que a aplicação de molibdênio causou decréscimo na intensidade da doença, bem como promoveu incrementos na área foliar, na taxa fotossintética líquida e na produção do feijoeiro. O controle químico da mancha angular deve ser realizado durante a fase de florescimento, através de uma ou duas aplicações fungicidas. Capítulo 5. No presente capítulo foi testado a aplicabilidade do equipamento LAI-2000 (Li-Cor) para estimar o índice de área foliar (LAI) do feijoeiro. Foi concluído que o equipamento pode ser empregado sem restrições na cultura do feijoeiro.<br>The main purpose of the thesis was to understand the effects of angular leaf spot (Phaeoisariopsis griseola) and rust (Uromyces appendiculatus) on the variables related to plant growth and yield of common bean (Phaseolus vulgaris). This thesis was organized in to five chapters. In the first two chapters data from three field experiments were analyzed using different approaches. The last three chapters referred to independent experiments. Chapter 1. The effects of angular leaf spot and rust, separately or combined, on host growth (expressed as area under leaf area progress curve - AULAPC, healthy leaf area duration - HAD, and healthy leaf area absorption - HAA) and yield of individual bean plants were investigated. All inoculated treatments had significantly more severe disease and less yield than the control treatment. In general, yield was not related to disease severity or area under disease progress curve. In contrast, the highest yields were always related to the highest values of HAD, and HAA. The relationship between yield and HAD, and HAA was linear. It was concluded that angular leaf spot reduced the leaf area because of defoliation while rust did not affect the leaf area. Rust reduced yield more than four times that of angular leaf spot, although the decrease in photosynthesis to angular leaf spot was twice that of rust. Chapter 2. The effect of angular leaf spot and rust, separately or combined, on leaf gas exchange (net photosynthetc rate, stomatal conductance, and transpiration) of common bean was reported. The inoculation of plants with P. griseola (P), U. appendiculatus (U), and a combination of the two pathogens (P+U) caused a significant reduction in the net photosynthetic rate and yield. Treatments P and P+U resulted in a significant reduction of stomatal conductance. The interactive effects of the pathogens on yield could be explained in part by the decreases in stomatal conductance and in the net photosynthetic rate of diseased bean leaves. Chapter 3. The relationships among angular leaf spot, healthy leaf area, effective leaf area, and pod yield of common bean were evaluated. Visual and virtual severity, and area under disease progress curve (AUDPC) showed no correlation with pod yield. However, healthy leaf area duration (HAD), healthy leaf area absorption (HAA), effective leaf area duration (ELAD), and effective leaf area absorption (ELAA) were significantly correlated with pod yield. The relationships between yield and HAD, HAA, ELAD, and ELAA were linear in each of the three trials. The slope of the yield-healthy leaf area index (HLAI) relationship proved to be stable, regardless of planting date and bean growth stage (from R6 to R8). HLAI is proposed as a key explanatory variable for a transportable system of disease management; it may be useful in producing precise recommendations at the farm level. Chapter 4. The strategies to manage angular leaf spot on common bean based in molybdenum application and chemical control were studied. It was observed that the molybdenum treatments showed smaller severity of angular leaf spot, and higher leaf area, net photosynthetic rate and yield, than the treatments that had no Mo. To control angular leaf spot, it was important to spray fungicide once or twice during the flowering period, which takes place ca. 25 to 45 days after planting. Chapter 5. The applicability of the equipment LAI-2000 (Li-Cor) to estimate leaf area index (LAI) was tested. It was concluded that the equipment could be used to estimate LAI on common bean.
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Washington, W. S. "The susceptibility of cultivated "rubus" varieties to "Phragmidium violaceum", the cause of blackberry leaf rust, and fungicides for the control of the disease /." Title page, contents and summary only, 1985. http://web4.library.adelaide.edu.au/theses/09A/09aw319.pdf.
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Vatter, Thomas [Verfasser]. "Locating QTL conferring resistance against net blotch, leaf rust, and stripe rust in the wild barley nested association mapping (NAM) population HEB-25 / Thomas Vatter." Halle, 2018. http://d-nb.info/1175950580/34.
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Singh, Lovepreet. "Characterization of new sources and superior gene combinations for durable resistance to leaf rust in barley." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/24783.
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One hundred fourteen barley lines were screened with diverse pathotypes (pts) of Puccinia hordei in the greenhouse (GH) and field to characterize resistance. The GH tests revealed the presence of all stage resistance (ASR) genes Rph1, Rph2, Rph3, Rph12 and Rph19 either individually or in combination, whereas field tests revealed the presence of adult plant resistance (APR) in 74.5% of the test lines. Molecular markers linked to known genes demonstrated presence of Rph15 (3 lines), Rph20 (5 lines), Rph23 (8 lines), Rph24 (19 lines), and the combinations Rph20+Rph23 or Rph20+Rph24 or Rph23+Rph24 (8 lines). The remaining 49 resistant lines probably carry new uncharacterized ASR and/or APR genes. Genome wide association studies (GWAS) detected a total of 15 QTL that were strongly associated with markers. Among them, QTL MTA8_R2 (chromosome 7H) has the largest effect in controlling leaf rust.
Temperature and interaction studies revealed that the expression of Rph1.a, Rph2.b, Rph4.d and Rph10.o altered with temperature, whereas the expression of genes Rph3.c, Rph5.e, Rph6.f, Rph12 (9.z), Rph13.x and Rph15.ad was concluded to be non-sensitive to temperature. Amongst a selection of lines carrying Rph20 (Flagship), Rph23 (Yerong) and Rph24 (ND24260), only seedlings of Flagship showed improved resistance with lower temperatures against pt 200 P-, whereas seedlings of Yerong and ND24260 showed high IT at all three temperatures with pt 5457 P+. When RphASR genes were combined with the APR gene Rph20, combinations Rph2.b+Rph20, Rph4.d+Rph20, Rph5.e+Rph20, Rph9.i+Rph20 and Rph15.ad+Rph20 showed an enhanced level of resistance. Seedlings carrying the combination Rph5.e+Rph20 remained resistant even when challenged with the Rph5.e-virulent pt 220 P+ + Rph13, suggesting a residual or ghost effect of Rph5.e when present in combination with Rph20. This study was the first to demonstrate that several ASR Rph genes interact with the APR gene Rph20 in an additive manner.
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Segovia, Vanesa. "Identification of wheat leaf rust (Puccinia triticina. ERIKS.) genes expressed during the early stages of infection." Diss., Kansas State University, 2010. http://hdl.handle.net/2097/6759.
Full textAbstract:
Doctor of Philosophy<br>Department of Plant Pathology<br>John P. Fellers<br>Harold Trick<br>In Kansas, wheat (Triticum aestivum L.) is severely affected by the biotrophic fungus Puccinia triticina (leaf rust). Although resistant varieties have been developed, the fungus tends to overcome new sources resistance very quickly. Plants have evolved a single gene (R genes) defense network that can recognize specific pathogen effectors (Avr), in a gene-for-gene manor. In rusts, effectors are secreted proteins responsible for inducing the uptake of nutrients and inhibit host defense responses. Identification of secreted proteins during the infection may help to understand the mode of infection of P. triticina. Little is known about molecular interactions in the pathosystem wheat-leaf rust and no Avr genes from cereal rusts have been cloned. In order to understand pathogenicity in leaf rust and generate new alternatives for disease control, the goal of this research is identify P. triticina secreted proteins from a collection of expressed genes during the infection, and to characterize putative Avr function for three candidates. From 432 EST’s derived from haustoria and infected plants, fifteen secreted proteins were identified and 10 were selected as potential avirulence candidates. Pt3 and Pt 51 are two P. triticina (Pt) candidates expressed specifically in the haustoria and encode small cysteine-rich secreted proteins. Eight candidates are expressed at early stages of infection, during spore germination and 6 days after inoculation. They are small-secreted proteins. None are repetitive elements or have nuclear localization signals. They also do not share a conserved motif with known filamentous fungus Avr proteins. Five candidates are novel proteins, two have similarity with predicted proteins, one is homologous with Hesp-379-like protein, one is homologous with superoxide dismutase, and one has a cell glucanase predicted function. Pt3, Pt12 and Pt27 were tested by transient expression experiments using co-bombardment with GUS into leaf rust resistant isogenic lines. Reduction in the expression of reporter gene GUS co-expressed with Pt27 indicates a potential avirulence factor for Lr26 in wheat.
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Martinati, Juliana Camargo. "Aspectos bioquímicos em plantas de cafeeiro tratadas com silício." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/64/64133/tde-03122009-154619/.
Full textAbstract:
A maioria das plantas consegue defender-se contra infecções fúngicas por meios naturais, que podem ser induzidos por uma série de elicitores bióticos ou abióticos. O silício (Si) solúvel tem mostrado que é capaz de induzir resistência em várias espécies de plantas contra inúmeros patógenos. Neste trabalho foi proposta a avaliação dos compostos contento Si na redução dos sintomas da ferrugem causada pelo fungo biotrófico Hemileia vastatrix em plantas de cafeeiros suscetíveis bem como avaliar os parâmetros bioquímicos envolvidos nos processos de resistência. Primeiramente, foram estudadas duas fontes de Si (silicato de Ca/Mg e silicato de potássio) em cinco doses para padronizar uma dose/fonte para os experimentos futuros. Foi possível observar que as plantas de cafeeiros não tiveram diferença significativa nos parâmetros de desenvolvimento como altura das plantas, área foliar, número de folhas para nenhuma das fontes e doses analisadas. Porém quando se tratava da contagem do número de lesões por cm2, a fonte silicato de potássio na dose de 5mM conseguiu suprimir em até 60% o desenvolvimento das lesões causadas pelo fungo. Com a fonte e dose estabelecidas, o segundo passo do trabalho foi avaliar quais os processos bioquímicos envolvidos na resistência conferida pelo Si em plantas de cafeeiro. Foram analisadas as atividades das enzimas relacionadas ao estresse oxidativo (peroxidases guaiacol e ascorbato, catalases, e superóxido desmutases) e relacionadas à defesa (glucanase, quitinase e PAL). As folhas foram coletadas para a obtenção do extrato protéico em diferentes intervalos de tempo após a inoculação com o fungo: as 24, 48, 72 e 96 horas após a inoculação e como controle foi utilizado o tempo zero (sem inoculação). Nesta fase foi possível observar que a atividade das enzimas CAT, SOD, APX foi maior em plantas tratadas indicando que o Si parece estimular uma resposta mais rápida ao estresse oxidativo. O mesmo ocorreu com as enzimas relacionadas à defesa. A partir destes resultados podemos afirmar que o Si estimula uma resposta de defesa mais rápida em plantas de café suscetíveis à ferrugem quando inoculadas com o fungo patogênico<br>Most plants can defend themselves against fungal infections by natural means, which can be induced by a number of biotic and abiotic elicitors. Soluble silicon (Si) has been shown to induce resistance in a number of plant species against several pathogens. The objective of this work was to assess the influence of silicon application of symptoms caused by the biotrophic fungus Hemileia vastatrix in susceptible coffee plants and evaluate the biochemistry process involved in defense mechanism. First of all, were studied two Si sources (Ca/Mg silicate and potassium silicate) in five doses to standardize dose/source for the future experiments. The statistical analysis showed that no difference was observed in relation to plant height, leaf area and number of leaves. However, the number of lesions reduced 60% in the higher silicon dose when compared to the number of lesions in control plants. Infected plants were found to have a linear decrease of lesions with the increase of silicate concentration. The lowest number of lesions per leaf area was observed in plants that received 5 M of Si from potassium silicate. This result indicates the use of silicon as an alternative for an ecological management system for coffee disease protection. The second step of this work was to evaluate the biochemistry process involved in resistance induced by Si in susceptible coffee plants. The activity of the enzymes related to oxidative stress (peroxidases, catalase, and superoxide desmutase) and related to defense (glucanase, chitinase, PAL) was evaluated. The leaves were collected in different time intervals after the fungus inoculation (24, 48, 72 e 96 hours after the fungus inoculation) in order to obtain the protein extract. It was possible to observe that the activity of CAT, SOD and APX was higher in Si-treated coffee plants suggesting that Si could stimulate a faster response to oxidative stress. The same situation occurred to the defense related enzymes. By the results obtained here it is possible to verify that Si can stimulate a faster defense response in susceptible coffee plants when inoculated with coffee leaf rust fungus
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Boylu, Baris. "Genetic Screening Of Turkish Wheat Varieties For The Durable Resistance Gene, Lr34." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613140/index.pdf.
Full textAbstract:
Wheat diseases such as rusts and powdery mildews are among the most
important and ancient diseases that affect wheat cultivation worldwide.
The pathogen race specific resistance genes cannot maintain long lasting
resistance. On the other hand, the presence of genes confers the non-race
specific resistance last much longer. The durable resistance phenotypes in
wheat against various rust and powdery mildew diseases were reported as
Lr34, Yr18, and Pm38 separately<br>nevertheless, they were known to locate
very close to each other based on linkage analysis. Recently, it was shown
that all of these resistance phenotypes are indeed conferred by the same
gene, encoding Adenosine triphosphate&ndash<br>binding cassette transporter
(ABC-transporter) type protein. The way with which this transporter is
functioning to maintain the durable resistance against different types of
pathogens is still unknown.
v
The presence of LR34 (or ABC-transporter) gene resistant allele can be
detected by specially designed markers. In spite of the few DNA sequence
differences between the resistant and the susceptible alleles, the easily
applicable PCR based markers allow the detection of the presence of this
durable resistant allele on any given variety or cultivar. In our study, 62
different Turkish bread wheat varieties were screened by the gene specific
molecular markers, developed from those LR34 gene mutation sites. The
11 cultivars determined to contain the resistant allele. This study is the
first screening of Turkish cultivars for the presence of LR34 gene.
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Schachermayr, Gabriele. "Identification and localization of molecular markers linked to leaf rust resistance genes in wheat (Triticum aestivum L.) /." [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10957.
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Harrison, Nicole Rezac. "Using next-generation sequencing technologies to develop new molecular markers for the leaf rust resistance gene Lr16." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/17662.
Full textAbstract:
Master of Science<br>Department of Plant Pathology<br>John P. Fellers<br>Allan K. Fritz<br>Leaf rust is caused by Puccinia triticina and is one of the most widespread diseases of wheat worldwide. Breeding for resistance is one of the most effective methods of control. Lr16 is a leaf rust resistance gene that provides partial resistance at the seedling stage. One objective of this study was to use RNA-seq and in silico subtraction to develop new resistance gene analog (RGA) markers linked to Lr16. RNA was isolated from the susceptible wheat cultivar Thatcher (Tc) and the resistant Thatcher isolines TcLr10, TcLr16, and TcLr21. Using in silico subtraction, Tc isoline ESTs that did not align to the Tc reference were assembled into contigs and analyzed using BLAST. Primers were designed from 137 resistance gene analog sequences not found in Tc. A population of 260 F[subscript]2 lines derived from a cross between the rust-susceptible cultivar Chinese Spring (CS) and a Thatcher isoline containing Lr16 (TcLr16) was developed for mapping these markers. Two RGA markers XRGA266585 and XRGA22128 were identified that mapped 1.1 cM and 23.8 cM from Lr16, respectively. Three SSR markers Xwmc764, Xwmc661, and Xbarc35 mapped between these two RGA markers at distances of 4.1 cM, 10.7 cM, and 16.1 cM from Lr16, respectively. Another objective of this study was to use genotyping-by-sequencing (GBS) to develop single nucleotide polymorphism (SNP) markers closely linked to Lr16. DNA from 22 resistant and 22 susceptible F[subscript]2 plants from a cross between CS and TcLr16 was used for GBS analysis. A total of 39 Kompetitive Allele Specific PCR (KASP) markers were designed from SNPs identified using the UNEAK and Tassel pipelines. The KASP marker XSNP16_TP1456 mapped 0.7 cM proximal to Lr16 in a TcxTcLr16 population consisting of 129 F[subscript]2 plants. These results indicate that both techniques are viable methods to develop new molecular markers. RNA-seq and in silico subtraction were successfully used to develop two new RGA markers linked to Lr16, one of which was more closely linked than known SSR markers. GBS was also successfully used on an F[subscript]2 population to develop a KASP marker that is the most closely linked marker to Lr16 to date.
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Aoun, Meriem. "Genomic Mapping of Leaf Rust and Stem Rust Resistance Loci in Durum Wheat and Use of RAD-Genotype by Sequencing for the Study of Population Genetics in Puccinia Titicina." Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25909.
Full textAbstract:
Leaf rust, caused by Puccinia triticina Erikss. (Pt), and stem rust, caused by Puccinia graminis f. sp. tritici Erikss. and E. Henn (Pgt), are among the most devastating diseases of durum wheat (Triticum turgidum L. var. durum). This study focused on the identification of Lr and Sr loci using association mapping (AM) and bi-parental population mapping. From the AM conducted on the USDA-National Small Grain Collection (NSGC), 37 loci associated with leaf rust response were identified, of which 14 were previously uncharacterized. Inheritance study and bulked segregant analysis on bi-parental populations developed from eight leaf rust resistance accessions from the USDA-NSGC showed that five of these accessions carry single dominant Lr genes on chromosomes 2B, 4A, 6BS, and 6BL. The other three accessions have Lr genes with more complex inheritance. All eight accessions carry different genes than those already mapped in durum cultivars except one accession with Lr61. Linkage mapping in two of the bi-parental populations showed that the gene in PI 209274 (LrCA) was mapped to 6BS between SNPs IWA3298 and IWB39456, while the gene in PI 192051 (LrPort) was mapped to 4AL, flanked by IWA4254 and IWA8341. Resistance to Pgt-race TTKSK was also observed in PI 534304 and PI 192051. PI 534304 was found to carry Sr13 on chromosome 6AL, while PI 192051 carries a novel Sr gene (SrPort) mapped to 7AS flanked by IW8390 and IWA1805. The genotype PI 192051 has an additional QTL (QSr.ndsu-5B) to Pgt races in a field trial in Ethiopia in 2016. The QSr.ndsu-5B was mapped to 5BL and delimited by IWA6992 and IWA2181. The study of virulence diversity in Pt isolates collected from several countries identified seven races among 51 isolates collected from durum wheat and 21 races among 40 isolates collected from common wheat. The phylogeny study on 30 Pt isolates based on the Restriction-Associated DNA (RAD)-Genotype by Sequencing (GBS), clustered the isolates into eight clades, with higher diversity in the SNP genotypes in common wheat isolates compared to that in durum wheat isolates. RAD-GBS is identified as a suitable and informative genotyping technique to study the population genetics of Pt.<br>North Dakota Wheat Commission<br>NDSU State Board of Agricultural Research and Education
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Fatima, Fizza. "Genome-Wide Association Study for Disease Traits In Wheat and Its Wild Relatives." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40900.
Full textAbstract:
Wheat is the most widely grown crop in the world and as such, is an essential source of energy and nutrition. The challenges that breeders presently face is to increase production to feed the rising population of the world, while also accounting for climate change, pollution, water and environmental stresses. As genetic uniformity of modern cultivars has increased vulnerability to pests and diseases, the wild relatives of wheat offer a rich source of genetic diversity and stress tolerance traits, that can be harnessed and transferred in to modern wheat.
In this study, we used array-based genotyping to explore genetic diversity in 385 domesticated and non-domesticated lines of wheat and their wild relatives. Genetic characterization using the wheat 90K array, and subsequent filtering and validation mapped 9,570 single nucleotide polymorphic markers onto the wheat reference genome. Phylogenetic analyses illustrated four major clades, clearly separating the wild species from the domesticated, and the ancient Triticum turgidum species from modern T. turgidum cultivars.
Using this diverse germplasm, a genome-wide association study (GWAS) was performed for leaf rust, the most widespread rust disease of wheat. Identification of novel sources of resistance is necessary to maintain disease resistance and stay ahead in the plant-pathogen evolutionary arms race. GWAS was conducted using eight statistical models for infection types against six leaf rust isolates and leaf rust severity rated in field trials for 3-4 years at 2-3 locations in Canada. Functional annotation of genes containing significant quantitative trait nucleotides (QTNs) identified 96 disease-related nucleotide associated with leaf rust resistance. A total of 21 QTNs were in haplotype blocks or within flanking markers of at least 16 known leaf rust (Lr) resistance genes. The remaining significant QTNs were considered loci that putatively harbor new Lr resistance genes. Future efforts to validate these loci will help understand their role in disease resistance and promote their utility for marker-assisted selection in pre-breeding.
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Saito, Belisa Cristina [UNESP]. "Characterization of corn inbred lines for disease resistance." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150400.
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Previous issue date: 2017-03-03<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>O milho é uma das culturas mais extensamente cultivadas em todo mundo. A incidência e a severidade de doenças têm aumentado significativamente nos últimos anos acarretando perdas no rendimento e afetando a qualidade dos grãos. Muitos trabalhos têm sido desenvolvidos na tentativa de identificar híbridos resistentes às principais doenças que acometem a cultura do milho, mas poucos são os relatos de estudos com linhagens. Dessa forma, o objetivo deste estudo foi: 1) identificar linhagens resistentes e susceptíveis com base na área abaixo da curva de progresso de doenças (AACPD) para os sintomas de ferrugem tropical (TR), ferrugem polissora (SR), cercosporiose (GLS), helmintosporiose (NLB), mancha marrom (PBS) e mancha branca (PLS); 2) identificar linhagens resistentes e suscetíveis com base nos parâmetros de adaptabilidade e estabilidade fenotípica para os sintomas de cercosporiose, helmintosporiose, mancha marrom e mancha branca; 3) identificar as melhores datas de semeadura, com a maior ocorrência das doenças, para fins de avaliação de linhagens e outros genótipos para resistência. Cinquenta linhagens, derivadas de populações com grãos flint e dent, foram avaliadas em blocos casualizados com três repetições, aos 45, 60, 75 e 90 dias após a semeadura em duas épocas, para medição da AACPD. Para a análise de adaptabilidade e estabilidade, 41 linhagens foram avaliadas em blocos casualizados com três repetições, 30 dias após o florescimento feminino, em onze épocas de semeadura, usando o método de análise de regressão. Foram atribuídas notas de 1, 2, 3, 4, 5, 6, 7, 8 e 9 correspondendo a 0, 1, 10, 20, 30, 40, 60, 80 e > 80% de área foliar com sintomas de doença. Para a AACPD, a análise de variância conjunta foi significativa para TR, SR, GLS e PLS e a interação linhagens x épocas foi significativa para ferrugem tropical e polissora. Para GLS e NLB as 41 linhagens foram classificadas como resistentes, sendo que as maiores severidades de doenças ocorreram nas semeaduras entre Junho e Setembro. As linhagens IVF1-3, IVF1-7, IVF1 -9, IVF1-10, IVF1 -11, IVF1 -25, IVF1-230, IVD1-2, IVD1 -2-1, IVD1-3, IVD1-9, IVD1 -12, 2F, 3F, 6F, 9F, 10F, 4C, 2D e 7D foram classificadas como resistentes para as doenças estudadas, sendo indicadas para o desenvolvimento de sintéticos. Para a mancha marrom e mancha branca, as semeaduras de Abril, Junho, Julho e Agosto apresentaram maiores severidades de doenças. As linhagens IVD1-9, IVD1-10, 7D, 10D e 2F podem ser indicadas no desenvolvimento de sintéticos resistentes.<br>Corn is one of the most widely cultivated crops in the worldwide. The incidence and severity of diseases affecting crops have increased significantly in the past years, leading to yield losses and affecting grain quality. Many studies have been carried out with the attempt to identify hybrids that are resistant to the main diseases, but few reports have studied inbred lines. Therefore, the objectives of this study were: 1) identify resistant and susceptible inbred lines based on the area under disease progress curve (AUDPC) for tropical rust, southern rust, gray leaf spot, northern leaf blight, physoderma brown spot and phaeosphaeria leaf spot; 2) identify resistant and susceptible inbred lines based on adaptability and stability parameters for symptoms of gray leaf spot (GLS), northern leaf blight (NLB), physoderma brown spot (PBS) and phaeosphaeria leaf spot (PLS); 3) identify the best planting dates, with the highest occurrence of diseases, for the purpose of evaluating inbred lines and other genotypes for resistance. For AUDPC, fifty inbred lines, derived from populations with flint and dent grains, were evaluated in randomized block designs with three replications, at 45, 60, 75 and 90 days after planting in two seasons. For the analysis of adaptability and stability, forty-one inbred lines were evaluated in randomized blocks with three replications, 30 days after silking, in eleven planting dates, using regression analysis method. The scale of scores from 1, 2, 3, 4, 5, 6, 7, 8 and 9 corresponding to 0, 1, 10, 20, 30, 40, 60, 80 and > 80% of leaf area with disease symptoms was used. For AUDPC, the joint analysis of variance was significant for TR, SR, GLS and PLS, while the interaction inbred lines x environments, was significant for TR and SR. For GLS and NLB, forty-one inbred lines were classified as resistant and the highest severities of diseases occurred in planting dates between June and September. The inbred lines IVF1-3, IVF1-7, IVF1 -9, IVF1-10, IVF1 -11, IVF1 -25, IVF1-230, IVD1-2, IVD1 -2-1, IVD1-3, IVD1-9, IVD1 -12, 2F, 3F, 6F, 9F, 10F, 4C, 2D and 7D were classified as resistant to the diseases studied and are indicated to produce synthetics. For PBS and PLS, the plating dates of April, June, July and August showed higher disease severity. The inbred lines IVD1-9, IVD1-10, 7D,10D and 2F may be indicated to produce synthetics.
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Seyfarth, Ralf. "Development of molecular markers for the adult plant leaf rust resistance genes Lr13 and Lr35 in wheat (Triticum aestivum L.) /." [S.l.] : [s.n.], 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13533.
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Njom, Henry Akum. "Mechanism and synchronicity of wheat (Triticum aestivum) resistance to leaf rust (Puccinia triticina) and Russian wheat aphid (Duiraphis noxia) SA1." Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/2700.
Full textAbstract:
Wheat (Triticum aestivum and T. Durum) is an extremely important agronomic crop produced worldwide. Wheat consumption has doubled in the last 30 years with approximately 600 million tons consumed per annum. According to the International Maize and Wheat Improvement Center, worldwide wheat demand will increase over 40 percent by 2020, while land as well as resources available for the production will decrease significantly if the current trend prevails. The wheat industry is challenged with abiotic and biotic stressors that lead to reduction in crop yields. Increase knowledge of wheat’s biochemical constitution and functional biology is of paramount importance to improve wheat so as to meet with this demand. Pesticides and fungicides are being used to control biotic stress imposed by insect pest and fungi pathogens but these chemicals pose a risk to the environment and human health. To this effect, there is re-evaluation of pesticides currently in use by the Environmental Protection Agency, via mandates of the 1996 Food Quality Protection Act and those with higher perceived risks are banned. Genetic resistance is now a more environmental friendly and effective method of controlling insect pest and rust diseases of wheat than the costly spraying with pesticides and fungicides. Although, resistant cultivars effectively prevent current prevailing pathotypes of leaf rust and biotypes of Russian wheat aphid from attacking wheat, new pathotypes and biotypes of the pathogen/pest may develop and infect resistant cultivars. Therefore, breeders are continually searching for new sources of resistance. Proteomic approaches can be utilised to ascertain target enzymes and proteins from resistant lines that could be utilised to augment the natural tolerance of agronomically favourable varieties of wheat. With this ultimate goal in mind, the aim of this study was to elucidate the mechanism and synchronicity of wheat resistance to leaf rust (Puccinia triticina) and Russian wheat aphid (Duiraphis noxia) SA1. To determine the resistance mechanism of the wheat cultivars to leaf rust infection and Russian wheat aphid infestation, a proteomics approach using two-dimensional gel electrophoresis was used in order to determine the effect of RWA SA1 on the wheat cultivars proteome. Differentially expressed proteins that were up or down regulated (appearing or disappearing) were identified using PDQuestTM Basic 2-DE Gel analysis software. Proteins bands of interest were in-gel trypsin digested as per the protocol described in Schevchenko et al. (2007) and analysed using a Dionex Ultimate 3000 RSLC system coupled to an AB Sciex 6600 TripleTOF mass spectrometer. Protein pilot v5 using Paragon search engine (AB Sciex) was used for comparison of the obtained MS/MS spectra with a custom database containing sequences of Puccinia triticina (Uniprot Swissprot), Triticum aestivum (Uniprot TrEMBL) and Russian wheat aphid (Uniprot TrEMBL) as well as a list of sequences from common contaminating proteins. Proteins with a threshold of ≥99.9 percent confidence were reported. A total of 72 proteins were putatively identified from the 37 protein spots excised originating from either leaf rust or Russian wheat aphid experiments. Sixty-three of these proteins were associated with wheat response to stress imposed by RWA SA1 feeding while 39 were associated with infection by Puccinia triticina. Several enzymes involved in the Calvin cycle, electron transport and ATP synthesis were observed to be differentially regulated suggesting greater metabolic requirements in the wheat plants following aphid infestation and leaf rust infection. Proteins directly associated with photosynthesis were also differentially regulated following RWA SA1 infestation and P.
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Dugyala, Sheshanka. "Towards Identifying the Physical and Molecular Components Involved in Resistance to Leaf Rust Pathogen Puccinia Triticina in Wheat and Barley." Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25829.
Full textAbstract:
Genetic resistance is the preferred method to reduce yield losses caused by many diseases including wheat leaf rust. However, in many cases host resistance seems to be short-lived. For decades, scientists have tried and continue trying to understand genetics and physical mechanisms involved in durable host resistance. Incompatible host-pathogen interactions in wheat- Puccinia triticina (Pt) pathosystem can be classified into pre-and post-haustorial. Post-haustorial resistance tends to be involved in race specific resistance and is commonly characterized by presence of hypersensitive reaction (HR), while pre-haustorial resistance do not generally involve HR. The objective of this work was to understand the physical and molecular components associated with resistance mechanisms to Pt. A set of Thatcher near isogenic lines (NIL) carrying different leaf rust (Lr) resistance genes and barley (non-host) genotypes were evaluated in time course experiments for histological analysis and relative fungal DNA quantification. Histological evaluation and q-PCR assay showed differences in time of fungal structures formation and amount of fungal DNA among genotypes. The q-PCR assay could differentiate between resistant and susceptible genotypes at 24 hpi. Additionally, Cq ratio of q-PCR assay allowed for classification of resistant genotypes carrying pre-haustorial (Lr9, Q21860) and those carrying post-haustorial resistance (Lr21, Lr34 and Harrington). To our surprise, despite carrying pre-haustorial resistance, Tc-Lr9 presented HR as early as 6 hpi. Tc-Lr21 presented HR, before (5 hpi) and after haustoria formation (24 hpi). To better characterize the HR and determine if the HR observed was the product of H2O2 accumulation, histochemical and gene expression studies were used. Both methods confirmed that the HR observed in Tc-Lr9 and Tc-Lr21 indeed involved H2O2 accumulation. In addition, up-regulation of hypersensitive induced resistance genes TaHIR1, TaHIR2 was observed in Tc-Lr9. Up-regulation of Tc-Lr21 gene at 5 hpi was observed in Tc-Lr21. The protocols developed and data obtained from this study provide opportunities for quantitatively assess components of resistance and suggest that some previous assumptions about plant-pathogen interaction in host and non-host systems should be revisited.
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Saito, Belisa Cristina. "Characterization of corn inbred lines for disease resistance /." Ilha Solteira, 2017. http://hdl.handle.net/11449/150400.
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Orientador: João Antonio da Costa Andrade<br>Resumo: O milho é uma das culturas mais extensamente cultivadas em todo mundo. A incidência e a severidade de doenças têm aumentado significativamente nos últimos anos acarretando perdas no rendimento e afetando a qualidade dos grãos. Muitos trabalhos têm sido desenvolvidos na tentativa de identificar híbridos resistentes às principais doenças que acometem a cultura do milho, mas poucos são os relatos de estudos com linhagens. Dessa forma, o objetivo deste estudo foi: 1) identificar linhagens resistentes e susceptíveis com base na área abaixo da curva de progresso de doenças (AACPD) para os sintomas de ferrugem tropical (TR), ferrugem polissora (SR), cercosporiose (GLS), helmintosporiose (NLB), mancha marrom (PBS) e mancha branca (PLS); 2) identificar linhagens resistentes e suscetíveis com base nos parâmetros de adaptabilidade e estabilidade fenotípica para os sintomas de cercosporiose, helmintosporiose, mancha marrom e mancha branca; 3) identificar as melhores datas de semeadura, com a maior ocorrência das doenças, para fins de avaliação de linhagens e outros genótipos para resistência. Cinquenta linhagens, derivadas de populações com grãos flint e dent, foram avaliadas em blocos casualizados com três repetições, aos 45, 60, 75 e 90 dias após a semeadura em duas épocas, para medição da AACPD. Para a análise de adaptabilidade e estabilidade, 41 linhagens foram avaliadas em blocos casualizados com três repetições, 30 dias após o florescimento feminino, em onze épocas de semeadura, us... (Resumo completo, clicar acesso eletrônico abaixo)<br>Doutor
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Carpenter, Neal Ryan. "Identification and Mapping of Resistance to Puccinia striiformis and Puccinia triticina in Soft Red Winter Wheat." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/89628.
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Disease resistance is critical in soft red winter wheat (Triticum aestivum L.) cultivars. Leaf rust caused by Puccinia triticina Eriks and stripe rust caused by Puccinia striiformis Westend. f.sp. tritici Eriks. are destructive pathogens of wheat. From 2014 to 2015 phenotypic data was collected at diverse locations for resistance to leaf rust (North Carolina, Texas, and Virginia) and stripe rust (Arkansas, North Carolina, Georgia, Texas, and Virginia) in a Pioneer ‘25R47’ /‘Jamestown’ (P47/JT) population composed of 186 F5:9 recombinant inbred lines (RILs). Analysis of the P47/JT population identified two quantitative trait loci (QTL) for leaf rust resistance on chromosome 5B and two QTL for stripe rust resistance on chromosomes 3B and 6A. Phenotypic variation (%) explained by the putative leaf rust resistance QTL of Jamestown on 5B was as high as 22.1%. Variation explained by the putative stripe rust resistance QTL of Jamestown on 3B and 6A was as high as 11.1 and 14.3%, respectively.
Jamestown is postulated to contain gene Lr18. Seedlings of 186 F5:9 recombinant inbred lines from the P47/JT population and 200 F2 seedlings from eight other crosses including Jamestown and/or the Lr18 host differential line RL6009 (Thatcher*6/Africa 43) were screened with P. triticina race TNRJJ. Genetic analysis of the populations was conducted to validate the presence of Lr18 in Jamestown. Results of linkage analysis identified SNP maker IWB41960 linked within 5 cM of gene Lr18 in all three populations.
From 2016 to 2017 phenotypic data was collected at diverse locations for resistance to leaf rust (Illinois, North Carolina, and Virginia) in a ‘2013412’ (PI 667644) / VA10W-21 (PI 676295) population (412/21) composed of 157 doubled haploid (DH) lines. The 412/21 DH lines were genotyped via genotyping by sequence (GBS). Analysis of the 412/21 population identified one quantitative trait loci (QTL) region associated with adult plant resistance to leaf rust on chromosome 1B. Phenotypic variation (%) explained by the putative leaf rust resistance QTL of 2013412 on 1B was as high as 40.1%. Kompetitive allele-specific (KASP) markers KASP_S1B_8414614 and KASP_S1B_8566239 were developed as markers for use in marker assisted selection.<br>Ph. D.
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Meakin, Helen. "Isolation and characterisation of genes expressed in haustoria during a compatible interaction between the wheat leaf rust Puccunia triticina and wheat (Triticum aestivum)." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408620.
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