Relevant bibliographies by topics / Resistance QTL

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Academic literature on the topic 'Resistance QTL'

Author: Grafiati
Published: 15 March 2025

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Journal articles on the topic "Resistance QTL"

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Drake-Stowe, Katherine, Nicolas Bakaher, Simon Goepfert, Berangere Philippon, Regis Mark, Paul Peterson, and Ramsey S. Lewis. "Multiple Disease Resistance Loci Affect Soilborne Disease Resistance in Tobacco (Nicotiana tabacum)." Phytopathology® 107, no. 9 (September 2017): 1055–61. http://dx.doi.org/10.1094/phyto-03-17-0118-r.

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Phytophthora nicotianae and Ralstonia solanacearum are two of the most important pathogens affecting tobacco worldwide. Greater insight regarding genetic systems controlling resistance to these two soilborne pathogens, as well as identification of DNA markers associated with genomic regions controlling this resistance, could aid in variety development. An evaluation of 50 historical tobacco lines revealed a high positive correlation between resistances to the two pathogens, preliminarily suggesting that some genomic regions may confer resistance to both pathogens. A quantitative trait loci (QTL) mapping experiment designed to investigate the genetic control of soilborne disease resistance of highly resistant ‘K346’ tobacco identified four QTL significantly associated with resistance to P. nicotianae (explaining 60.0% of the observed phenotypic variation) and three QTL to be associated with R. solanacearum resistance (explaining 50.3% of the observed variation). The two QTL with the largest effect on Phytophthora resistance were also found to be the QTL with the greatest effects on resistance to Ralstonia. This finding partially explains previously observed associations between resistances to these two pathogens among U.S. current cultivars and within breeding populations. Further study is needed to determine whether these relationships are due to the same genes (i.e., pleiotropy) or favorable coupling-phase linkages that have been established over time.
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Miedaner, Thomas, and Viktor Korzun. "Marker-Assisted Selection for Disease Resistance in Wheat and Barley Breeding." Phytopathology® 102, no. 6 (June 2012): 560–66. http://dx.doi.org/10.1094/phyto-05-11-0157.

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Marker-assisted selection (MAS) provides opportunities for enhancing the response from selection because molecular markers can be applied at the seedling stage, with high precision and reductions in cost. About each of 50 genes conferring monogenic resistances and hundreds of quantitative trait loci (QTL) for quantitative disease resistances have been reported in wheat and barley. For detecting single-major gene resistance, MAS could be easily applied, but is often not necessary because the resistances are selected phenotypically. In quantitative disease resistances, MAS would be very useful, but the individual QTL often have small effects. Additionally, only a few monogenic resistances are durable and only a few QTL with high effects have been successfully transferred into elite breeding material. Further economic and biological constraints, e.g., a low return of investment in small-grain cereal breeding, lack of diagnostic markers, and the prevalence of QTL–background effects, hinder the broad implementation of MAS. Examples in which MAS has been successfully applied to practical breeding are the wheat rust resistance genes Lr34 and Yr36, the eyespot resistance gene Pch1, the recessive resistance genes rym4/rym5 to barley yellow mosaic viruses, mlo to barley powdery mildew, and two QTL for resistance to Fusarium head blight in wheat (Fhb1 and Qfhs.ifa-5A). Newly identified broad-spectrum resistance genes/QTL conferring resistance to multiple taxa of pathogens offer additional perspectives for MAS. In the future, chip-based, high-throughput genotyping platforms and the introduction of genomic selection will reduce the current problems of integrating MAS in practical breeding programs and open new avenues for a molecular-based resistance breeding.
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Zwonitzer, John C., Nathan D. Coles, Matthew D. Krakowsky, Consuelo Arellano, James B. Holland, Michael D. McMullen, Richard C. Pratt, and Peter J. Balint-Kurti. "Mapping Resistance Quantitative Trait Loci for Three Foliar Diseases in a Maize Recombinant Inbred Line Population—Evidence for Multiple Disease Resistance?" Phytopathology® 100, no. 1 (January 2010): 72–79. http://dx.doi.org/10.1094/phyto-100-1-0072.

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Southern leaf blight (SLB), gray leaf spot (GLS), and northern leaf blight (NLB) are all important foliar diseases impacting maize production. The objectives of this study were to identify quantitative trait loci (QTL) for resistance to these diseases in a maize recombinant inbred line (RIL) population derived from a cross between maize lines Ki14 and B73, and to evaluate the evidence for the presence genes or loci conferring multiple disease resistance (MDR). Each disease was scored in multiple separate trials. Highly significant correlations between the resistances and the three diseases were found. The highest correlation was identified between SLB and GLS resistance (r = 0.62). Correlations between resistance to each of the diseases and time to flowering were also highly significant. Nine, eight, and six QTL were identified for SLB, GLS, and NLB resistance, respectively. QTL for all three diseases colocalized in bin 1.06, while QTL colocalizing for two of the three diseases were identified in bins 1.08 to 1.09, 2.02/2.03, 3.04/3.05, 8.05, and 10.05. QTL for time to flowering were also identified at four of these six loci (bins 1.06, 3.04/3.05, 8.05, and 10.05). No disease resistance QTL was identified at the largest-effect QTL for flowering time in bin 10.03.
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Lana, Ubiraci Gomes de Paula, Isabel Regina Prazeres de Souza, Roberto Willians Noda, Maria Marta Pastina, Jurandir Vieira Magalhaes, and Claudia Teixeira Guimaraes. "Quantitative Trait Loci and Resistance Gene Analogs Associated with Maize White Spot Resistance." Plant Disease 101, no. 1 (January 2017): 200–208. http://dx.doi.org/10.1094/pdis-06-16-0899-re.

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Maize white spot (MWS), caused by the bacterium Pantoea ananatis, is one of the most important maize foliar diseases in tropical and subtropical regions, causing significant yield losses. Despite its economic importance, genetic studies of MWS are scarce. The aim of this study was to map quantitative trait loci (QTL) associated with MWS resistance and to identify resistance gene analogs (RGA) underlying these QTL. QTL mapping was performed in a tropical maize F2:3 population, which was genotyped with simple-sequence repeat and RGA-tagged markers and phenotyped for the response to MWS in two Brazilian southeastern locations. Nine QTL explained approximately 70% of the phenotypic variance for MWS resistance at each location, with two of them consistently detected in both environments. Data mining using 112 resistance genes cloned from different plant species revealed 1,697 RGA distributed in clusters within the maize genome. The RGA Pto19, Pto20, Pto99, and Xa26.151.4 were genetically mapped within MWS resistance QTL on chromosomes 4 and 8 and were preferentially expressed in the resistant parental line at locations where their respective QTL occurred. The consistency of QTL mapping, in silico prediction, and gene expression analyses revealed RGA and genomic regions suitable for marker-assisted selection to improve MWS resistance.
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Soriano, Jose Miguel, and Conxita Royo. "Dissecting the Genetic Architecture of Leaf Rust Resistance in Wheat by QTL Meta-Analysis." Phytopathology® 105, no. 12 (December 2015): 1585–93. http://dx.doi.org/10.1094/phyto-05-15-0130-r.

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Leaf rust is an important disease that causes significant yield losses in wheat. Many studies have reported the identification of quantitative trait loci (QTL) controlling leaf rust resistance; therefore, QTL meta-analysis has become a useful tool for identifying consensus QTL and refining QTL positions among them. In this study, QTL meta-analysis was conducted using reported results on the number, position, and effects of QTL for leaf rust resistance in bread and durum wheat. Investigation of 14 leaf rust resistance traits from 19 studies involving 20 mapping populations and 33 different parental lines provided information for 144 unique QTL that were projected onto the Wheat Composite 2004 reference map. In total, 35 meta-QTL for leaf rust resistance traits were identified in 17 wheat chromosomes and 13 QTL remained as unique QTL. The results will facilitate further work on the cloning of QTL for pyramiding minor- and partial-effect resistance genes to develop varieties with durable resistance to leaf rust.
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Abdelmajid, Kassem My, Laura Ramos, Leonor Leandro, Gladys Mbofung, David L. Hyten, Stella K. Kantartzi, Robert L. Grier IV, Victor N. Njiti, Silvia Cianzio, and Khalid Meksem. "The ‘PI 438489B’ by ‘Hamilton’ SNP-Based Genetic Linkage Map of Soybean [Glycine max (L.) Merr.] Identified Quantitative Trait Loci that Underlie Seedling SDS Resistance." Plant Genetics, Genomics, and Biotechnology 1, no. 1 (June 15, 2017): 18–30. http://dx.doi.org/10.5147/pggb.v1i1.148.

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Soybeans [Glycine max (L.) Merr.] are susceptible to many diseases including fungal diseases such as soybean sudden death syndrome (SDS). Several studies reported SDS resistance quantitative trait loci (QTL) on the soybean genome using different recombinant inbred line (RIL) populations and low density genetic linkage maps. High density exclusively single nucleotide polymorphisms-based (SNP-based) maps were not yet reported in soybean. The objectives of this study were (1) to construct a high density SNP-based genetic linkage map of soybean using the ‘PI438489B’ by ‘Hamilton’ (PIxH, n=50) recombinant inbred line population, and (2) to map QTL for SDS resistance using this high-density reliable genetic SNP-based map. The PI438489B by Hamilton high-density SNP-based genetic map was a high density map composed of 31 LGs, 648 SNPs, and covered 1,524.7 cM with an average of 2.37 cM between two adjacent SNP markers. Fourteen significant QTL were identified for SDS resistance using interval mapping (IM) and composite interval mapping (CIM) with LOD scores that ranged between 2.6 and 5.0. Twelve QTL were identified for foliar disease severity (FDS) and three QTL for root rot severity (RRS) of which one QTL underlain both FDS and RRS. The fourteen QTL were mapped onto ten separate chromosomes of the soybean genome. Seven of the intervals encompassing the QTL had been identified previously (on LGs C1, C2, D1b, G, L, N and O) associated with resistance to SDS but seven were novel (LGs A2 (2), B1, C2, D1a, D1b and O). We constructed the first PI438489B by Hamilton exclusively SNP-Based map and identified fourteen QTL that underlie SDS resistance including both resistances to foliar and root rot symptoms caused by Fusarium virguliforme infection. The QTL discovered here for SDS resistance could be useful to include in breeding programs in developing soybean cultivars resistant to SDS.
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Hackenberg, Dieter, Elvis Asare-Bediako, Adam Baker, Peter Walley, Carol Jenner, Shannon Greer, Lawrence Bramham, et al. "Identification and QTL mapping of resistance to Turnip yellows virus (TuYV) in oilseed rape, Brassica napus." Theoretical and Applied Genetics 133, no. 2 (November 5, 2019): 383–93. http://dx.doi.org/10.1007/s00122-019-03469-z.

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Abstract Key message Partially dominant resistance to Turnip yellows virus associated with one major QTL was identified in the natural allotetraploid oilseed rape cultivar Yudal. Abstract Turnip yellows virus (TuYV) is transmitted by the peach-potato aphid (Myzus persicae) and causes severe yield losses in commercial oilseed rape crops (Brassica napus). There is currently only one genetic resource for resistance to TuYV available in brassica, which was identified in the re-synthesised B. napus line ‘R54’. In our study, 27 mostly homozygous B. napus accessions, either doubled-haploid (DH) or inbred lines, representing a diverse subset of the B. napus genepool, were screened for TuYV resistance/susceptibility. Partial resistance to TuYV was identified in the Korean spring oilseed rape, B. napus variety Yudal, whilst the dwarf French winter oilseed rape line Darmor-bzh was susceptible. QTL mapping using the established Darmor-bzh × Yudal DH mapping population (DYDH) revealed one major QTL explaining 36% and 18% of the phenotypic variation in two independent experiments. A DYDH line was crossed to Yudal, and reciprocal backcross (BC1) populations from the F1 with either the susceptible or resistant parent revealed the dominant inheritance of the TuYV resistance. The QTL on ChrA04 was verified in the segregating BC1 population. A second minor QTL on ChrC05 was identified in one of the two DYDH experiments, and it was not observed in the BC1 population. The TuYV resistance QTL in ‘R54’ is within the QTL interval on Chr A04 of Yudal; however, the markers co-segregating with the ‘R54’ resistance are not conserved in Yudal, suggesting an independent origin of the TuYV resistances. This is the first report of the QTL mapping of TuYV resistance in natural B. napus.
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Esvelt Klos, K., T. Gordon, P. Bregitzer, P. Hayes, X. M. Chen, I. A. del Blanco, S. Fisk, and J. M. Bonman. "Barley Stripe Rust Resistance QTL: Development and Validation of SNP Markers for Resistance to Puccinia striiformis f. sp. hordei." Phytopathology® 106, no. 11 (November 2016): 1344–51. http://dx.doi.org/10.1094/phyto-09-15-0225-r.

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Quantitative trait loci (QTL) for barley stripe rust resistance were mapped in recombinant inbred lines (RIL) from a ‘Lenetah’ × ‘Grannelose Zweizeilige’ (GZ) cross. GZ is known for a major seedling resistance QTL on chromosome 4H but linked markers suitable for marker-assisted selection have not been developed. This study identified the 4H QTL (log of the likelihood [LOD] = 15.94 at 97.19 centimorgans [cM]), and additional QTL on chromosomes 4H and 6H (LOD = 5.39 at 72.7 cM and 4.24 at 34.46 cM, respectively). A QTL on chromosome 7H (LOD = 2.04 at 81.07 cM) was suggested. All resistance alleles were derived from GZ. Evaluations of adult plant response in Corvallis, OR in 2013 and 2015 provided evidence of QTL at the same positions. However, the minor QTL on 4H was not statistically significant in either location/year, while the 7H QTL was significant in both. The single-nucleotide polymorphism markers flanking the resistance QTL were validated in RIL from a ‘95SR316A’ × GZ cross for their ability to predict seedling resistance. In 95SR316A × GZ, 91 to 92% of RIL with GZ alleles at the major 4H QTL and at least one other were resistant to moderate in reaction. In these populations, at least two QTL were required to transfer the barley stripe rust resistance from GZ.
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Odilbekov, He, Armoniené, Saripella, Henriksson, Singh, and Chawade. "QTL Mapping and Transcriptome Analysis to Identify Differentially Expressed Genes Induced by Septoria Tritici Blotch Disease of Wheat." Agronomy 9, no. 9 (September 4, 2019): 510. http://dx.doi.org/10.3390/agronomy9090510.

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Resistance to Septoria tritici blotch (STB) is an economically important trait in many wheat-breeding programs across the world. Several quantitative trait loci (QTL) for STB resistance were identified in wheat but due to the dynamic pathogen population it is necessary to continuously identify new resistance genes/QTL and determine the underlying resistance mechanism. In this work, we integrated QTL mapping and transcriptome profiling to identify candidate genes underlying QTL associated with STB resistance in bread wheat at the seedling stage. The results revealed four QTL on chromosomes 1BS, 1BL, 3AS and 3DL for STB resistance. Among these, two QTL on 2BL and 3DL were mapped for chlorosis, necrosis and pycnidia while the other two on 1BS and 3AS were associated with necrosis and pycnidia. Among the four identified QTL, genes were identified in three QTL (1BS, 2BL and 3DL). In total, 238 differentially expressed genes (DEGs) were localized in 1BS, 16 DEGs in 2BL and 80 DEGs in 3DL QTL region respectively. F-box protein, NBS-LRR disease resistance genes and receptor-like protein kinase were the most over-represented. The results emphasize the importance of integrating QTL and transcriptome analysis to accelerate the identification of key genes underlying the traits of interest.
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Chunthawodtiporn, Jareerat, Theresa Hill, Kevin Stoffel, and Allen Van Deynze. "Genetic Analysis of Resistance to Multiple Isolates of Phytophthora capsici and Linkage to Horticultural Traits in Bell Pepper." HortScience 54, no. 7 (July 2019): 1143–48. http://dx.doi.org/10.21273/hortsci13359-18.

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Phytophthora capsici is one of the major pathogens found in pepper production, especially in bell pepper. Due to the high level of genetic diversity of the pathogen, bell pepper varieties with broad genetic resistance are essential for disease management. Criollo de Morelos – 334 (CM334), a landrace that has a high level of genetic resistance to P. capsici, has been used as the resistant source for P. capsici to generate a recombinant inbred line (RIL) population with the susceptible bell pepper cultivar Maor. From the resulting population, quantitative trait locus (QTL) models explaining resistance to each of four isolates of P. capsici were derived from QTL regions on three chromosomes using stepwiseqtl in R/qtl. A single region of chromosome 5 contained major QTL for resistance to each of the four isolates. Two isolate-specific QTL conferring resistance to isolates PWB53 and PWB106 were located on chromosomes 10 and 11, respectively. Both isolate-specific QTL had epistatic interactions with a major QTL on chromosome 5. Using the pepper reference genome and gene annotation, candidate genes for P. capsici resistance within 1.5-logarithm of odds (LOD) interval were identified. Based on functional annotations derived from Arabidopsis thaliana and solanaceous crop databases, multiple candidate genes related to resistance (R) gene complexes or to plant immune system were found under the QTL on all three chromosomes. A comparison of the locations of resistance QTL and previously identified horticultural QTL using the same population revealed tight linkage between resistance to P. capsici and a stem pubescence QTL o chromosome 10. Both candidate genes for P. capsici resistance and the linkages between resistance and horticultural traits could be applied for selection to broad resistance to P. capsici in bell pepper–breeding programs.
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Dissertations / Theses on the topic "Resistance QTL"

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Sabry, Ahmed Mohamed-Bashir. "QTL mapping of resistance to sorghum downy mildew in maize." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/460.

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Sorghum downy mildew (SDM) of maize is caused by the oomycete Peronosclerospora sorghi (Weston and Uppal) C. G. Shaw. The disease can cause devastating yield losses in maize (Zea mays L.). Quantitative trait loci (QTLs) mediating resistance to SDM were mapped using both restriction fragment length polymorphisms (RFLPs), and simple sequence repeats (SSRs) in 220 F2 individual maize progeny derived from a cross between two extremes; highly susceptible inbred parent SC-TEP5-19-1-3-1-4-1-1 (white) and highly resistant inbred P345C4S2B46-2-2-1-2-B-B-B (yellow). The phenotypic expression was assessed on F2:3 families in a wide range of environments under natural field infection and in a controlled greenhouse screening method. Heritability estimates of disease reaction ranged from 93.3% in Thailand sit 1 to 48% in Thailand sit 2. One hundred and thirty three polymorphic markers were assigned to the ten chromosomes of maize with LOD scores exceeding 4.9 covering about 1265 cM with an average interval length between markers of 9.5 cM. About 90% of the genome was located within a 10 cM distance to the nearest marker. Three putative QTLs were detected in association with resistance to SDM in different environments using composite interval mapping. Despite environmental and symptom differences, one QTL on chromosome 2 bin 9 had a major effect in all trials and explained up to 70% of the phenotypic variation in Thailand where the highest disease pressure was experienced. Two other QTLs on chromosome 3 bin 5 and chromosome 9 bin 2 had a minor effect, each explaining no more than 4% of the phenotypic variation. These results revealed one major gene and two minor genes that control sorghum downy mildew resistance. These markers should be very useful in breeding programs in facilitating the introgression of the resistance genes into commercial varieties. Marker-assisted selection for these loci should be useful in incorporating SDM resistance genes in maize across environments, even in the absence of the pathogen.
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Gambone, Katherine. "Mapping stem rust resistance genes in ‘Kingbird’." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32496.

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Master of Science
Department of Plant Pathology
William Bockus
Robert Bowden
Stem rust, caused by the fungus Puccinia graminis f. sp. tritici, has historically been one of the most important diseases of wheat. Although losses have been much reduced in the last fifty years, new highly virulent races of the pathogen have recently emerged in East Africa. These new races are virulent on nearly all of the currently deployed resistance genes and therefore pose a serious threat to global wheat production. The spring wheat variety ‘Kingbird’ is thought to contain multiple quantitative trait loci (QTLs) that provide durable, adult-plant resistance against wheat stem rust. Stem rust-susceptible Kansas winter wheat line ‘KS05HW14’ was backcrossed to Kingbird and 379 recombinant lines were advanced to BC₁F₅ and then increased for testing. The lines were screened for stem rust resistance in the greenhouse and field in Kansas and in the field in Kenya over multiple years. We identified 16,237 single nucleotide polymorphisms (SNPs) with the Wheat 90K iSelect SNP Chip assay. After filtering for marker quality, linkage maps were constructed for each wheat chromosome. Composite interval mapping and multiple-QTL mapping identified seven QTLs on chromosome arms 2BL, 2DS, 3BS, 3BSc, 5DL, 7BL, and 7DS. Six QTLs were inherited from Kingbird and one QTL on 7BL was inherited from KS05HW14. The location of the QTL on 2BL is approximately at locus Sr9, 3BS is at Sr2, 3BSc is at Sr12, and 7DS is at Lr34/Yr18/Sr57. Although no QTL was found on 1BL, the presence of resistance gene Lr46/Yr29/Sr58 on 1BL in both parents was indicated by the gene-specific marker csLV46. QTLs on 2DS and 5DL may be related to photoperiod or vernalization genes. Pairwise interactions were only observed with race QFCSC, most notably occurring with QTLs 2BL and 3BSc. These results confirm that there are multiple QTLs present in Kingbird. Ultimately, the identification of the QTLs that make Kingbird resistant will aid in the understanding of durable, non-race-specific resistance to stem rust of wheat.
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Cai, Jin. "Mapping QTL for fusarium head blight resistance in Chinese wheat landraces." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/13703.

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Master of Science
Department of Agronomy
Allan Fritz
Fusarium head blight (FHB) is one of the most devastative diseases in wheat. Growing resistant cultivars is one of the most effective strategies to minimize the disease damage. Huangcandou (HCD) is a Chinese wheat landrace showing a high level of resistance to FHB spread within a spike (type II). To identify quantitative traits loci (QTL) for resistance in HCD, a population of 190 recombinant inbred lines (RILs) were developed from a cross between HCD and Jagger, a susceptible hard winter wheat (HWW) released in Kansas. The population was evaluated for type II resistance at the greenhouses of Kansas State University. After initial marker screening, 261 polymorphic simple-sequence repeats (SSR) between parents were used for analysis of the RIL population. Among three QTL identified, two from HCD were mapped on the short arms of chromosomes 3B (3BS) and 3A (3AS). The QTL on the distal end of 3BS showed a major effect on type II resistance in all three experiments. This QTL coincides with a previously reported Fhb1, and explained 28.3% of phenotypic variation. The QTL on 3AS explained 9.7% of phenotypic variation for mean PSS over three experiments. The third QTL from chromosome 2D of Jagger explained 6.5% of phenotypic variation. Allelic substitution using the closest marker to each QTL revealed that substitution of Jagger alleles of two QTL on 3AS and 3BS with those from HCD significantly reduced the PSS. HCD containing both QTL on 3AS and 3BS with a large effect on type II resistance can be an alternative source of FHB resistance for improving FHB type II resistance in wheat. Besides, meta-analyses were used to estimate 95% confidence intervals (CIs) of 24 mapped QTL in five previously mapped populations derived from Chinese landraces: Wangshuibai (WSB), Haiyanzhong (HYZ), Huangfangzhu (HFZ), Baishanyuehuang (BSYH) and Huangcandou (HCD). Nineteen QTL for FHB type II resistance were projected to 10 QTL clusters. Five QTL on chromosomes 1A, 5A, 7A, and 3BS (2) were identified as confirmed QTL that have stable and consistent effects on FHB resistance and markers in these meta-QTL regions should be useful for marker-assisted breeding.
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Fytrou, Anastasia. "Drosophila immunity : QTL mapping, genetic variation and molecular evolution." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4742.

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Drosophila is involved in a wide range of interactions with parasites and pathogens (parasitoid wasps, bacteria, fungi, viruses). Drosophila hosts vary greatly at the species, population and individual level, in their response against such organisms, and much of this variation has a genetic basis. In this thesis I explored three aspects of this variation. First, using recombination mapping based on SNPs and a variation of bulk segregant analysis, I identified a QTL region on the right arm of the third chromosome of D. melanogaster associated with resistance to at least some of the parasitoid species / strains used in the experiments. The location of the QTL was further explored with deficiency complementation mapping and was narrowed down to the 96D1-97B1 region. The success of the deficiency mapping suggests that the resistant allele is not completely dominant. Second, I investigated patterns of molecular evolution in a set of immunity-related genes, using sequences from a D. melanogaster and a D. simulans population and a set of genes without known involvement in immunity for comparison. I found evidence that several of these genes have evolved under different selection pressure in each species, possibly indicating interactions with different parasites. The immunity genes tested appear to be evolving faster compared to non-immunity genes, supporting the idea that the immune system is evolving under strong selective pressure from parasites. Finally, in a D. melanogaster – sigma virus system, I measured genetic variation in the transmission of different virus genotypes, in different environments. There was poor correlation between temperatures, suggesting that environmental heterogeneity could constraint evolution of resistance (to virus transmission). The correlation between viral genotypes was also low, although relatively stronger for more closely phylogenetically related viral strains. Such interactions between host genotypes, virus genotypes and environmental conditions can maintain genetic variation in virus transmission.
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Wright, Emily Elizabeth. "Identification of Native FHB Resistance QTL in the SRW Wheat Cultivar Jamestown." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/64327.

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Fusarium Head Blight (FHB) is a devastating fungal disease of wheat (Triticum aestivum L.) and results in significant economic losses due to reductions in grain yield and the accumulation of mycotoxins, such as deoxynivalenol (DON) and nivalenol (NIV). As a result, breeding programs have been working to identify resistance genes in wheat varieties known to be resistant to FHB. Some of the major quantitative trait loci (QTL) for FHB resistance identified to date have been from exotic sources such as 'Sumai3' and the Chinese landrace Wangshuibai, and native resistance has been identified in North American cultivars such as Ernie and Truman which are being used in breeding programs. This study was conducted to characterize and map QTL for resistance to FHB in the soft red winter wheat cultivar Jamestown and to identify tightly linked DNA markers associated with those QTL so that marker-assisted selection (MAS) can be used in pyramiding these and other known QTL into elite backgrounds. Types of resistance assessed in this study include: Type I (resistance to initial infection; incidence), Type II (resistance to spread in wheat spike; severity), and decreases in mycotoxin accumulation (DON) and percentage of Fusarium damaged kernels (FDK). A population composed of 186 F5:7 recombinant-inbred lines (RILs) from the cross Pioneer Brand '25R47'/Jamestown were used to evaluate these traits in six environments (MD, NC, and VA in 2011 and 2012). This study identified a QTL for resistance to DON accumulation and FHB severity on the wheat chromosome 1B. The QTL accounted for 12.7% to 13.3% of the phenotypic variation in DON accumulation and 26.1% of the phenotypic variation in FHB severity. The most diagnostic marker for the QTL on chromosome 1B associated with resistance to FHB severity and DON accumulation is Xwmc500.6 located 7.2 cM from the QTL peak and flanked by markers Xwmc500.7 and Xgwm273.2 (28.2 cM interval).
Master of Science
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Asea, Godfrey Rox. "Genetic characterization of partial resistance and comparative strategies for improvement of host-resistance to multiple foliar pathogens of maize." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133833939.

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Lee, Jonghoon, Nur K. Izzah, Murukarthick Jayakodi, Sampath Perumal, Ho J. Joh, Hyeon J. Lee, Sang-Choon Lee, et al. "Genome-wide SNP identification and QTL mapping for black rot resistance in cabbage." BioMed Central Ltd, 2015. http://hdl.handle.net/10150/610296.

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BACKGROUND: Black rot is a destructive bacterial disease causing large yield and quality losses in Brassica oleracea. To detect quantitative trait loci (QTL) for black rot resistance, we performed whole-genome resequencing of two cabbage parental lines and genome-wide SNP identification using the recently published B. oleracea genome sequences as reference. RESULTS: Approximately 11.5 Gb of sequencing data was produced from each parental line. Reference genome-guided mapping and SNP calling revealed 674,521 SNPs between the two cabbage lines, with an average of one SNP per 662.5 bp. Among 167 dCAPS markers derived from candidate SNPs, 117 (70.1%) were validated as bona fide SNPs showing polymorphism between the parental lines. We then improved the resolution of a previous genetic map by adding 103 markers including 87 SNP-based dCAPS markers. The new map composed of 368 markers and covers 1467.3 cM with an average interval of 3.88 cM between adjacent markers. We evaluated black rot resistance in the mapping population in three independent inoculation tests using F₂:₃ progenies and identified one major QTL and three minor QTLs. CONCLUSION: We report successful utilization of whole-genome resequencing for large-scale SNP identification and development of molecular markers for genetic map construction. In addition, we identified novel QTLs for black rot resistance. The high-density genetic map will promote QTL analysis for other important agricultural traits and marker-assisted breeding of B. oleracea.
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Singh, Gurminder. "Resistance Screening and QTL Mapping in Wheat and Triticale Against Root-Lesion Nematode." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31886.

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Root-lesion nematode (RLN, Pratylenchus neglectus) invades the roots of wheat and causes yield losses throughout the world. Genetic resistance is the most economical and effective means to manage RLNs. The objective of this study were to identify source of resistance to RLN in a small collection of wheat germplasm and to map quantitative trait loci (QTL) associated with RLN resistance in two; one wheat and one triticale recombinant inbred line (RIL) populations. Out of wheat lines, three were resistant, including hard red spring wheat cultivars Brennan, SY Ingmar, and SY Soren. A number of genomic regions in wheat and rye were identified as QTL for RLN resistance. My research provides a better understanding of the genetic basis of P. neglectus resistance and important tools for RLN resistance breeding.
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Pirseyedi, Seyed Mostafa. "QTL Analysis for Fusarium Head Blight Resistance in Tunisian-Derived Durum Wheat Populations." Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27014.

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Durum (2n=4x=28; AABB) wheat is the grain of choice for the production of high-quality pasta products. Fusarium spp. are causal pathogens for Fusarium Head Blight (FHB). Limited host resistance to this disease exists among adapated durum cultivars. The use of Tunisian-derived durum lines for integration of FHB resistance in cultivars was evaluated. The genetic characterization of FHB resistance was evaluated, and markers assosciated with FHB resistance are presented in two populations. Two backcross inbred line (BIL) populations derived from cross between a resistant durum genotype `Tunisian 108' and susceptible durum wheat cultivars `Ben' and `Lebsock' were screened to identify QTL for FHB resistance. Analysis of variance showed significant effect of genotypes on FHB severity and incidence despite high level of interaction between environment and genotypes. A total of 329 and 331 DArT and microsatellite markers covered a distance of 1887.6 and 1748 cM in two populations respectively. Composite interval mapping using two linkage maps and the phenotypic data revealed 11 different FHB resistance QTL on seven different chromosomes (1A, 1B, 2B, 3B, 5A, 5B, and 7B) in Tunisian/Ben derived population and 15 different FHB resistant QTL on seven different chromosomes (1A, 1B, 3A, 3B, 4A, 5A, and 6B) in population derived from cross between Tunisian/Lebsock. At least two novel QTL were identified on chromosome 2B (Qfhb.ndsu-2B) 4A (Qfhs.ndsu-4A) in Tunisian/Ben//Ben and Tunisian/Lebsock//Lebsock population respectively. Location of the two FHB resistance QTL on chromosome 1B and two QTL on 5A were identical in both populations. Owing to cumulative effects of resistance QTL, high level of transgressive segregation was observed in both populations. Our finding revealed an alternative tetraploid FHB resistance source from Tunisian genomic background that can be utilized with associated markers for wheat geremplasm enhancement.
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Wang, Hehe. "Identification and Dissection of Soybean QTL Conferring Resistance to Phytophthora sojae." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1321389470.

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Book chapters on the topic "Resistance QTL"

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Sun, Jingxian, Duo Lv, Yue Chen, Jian Pan, Run Cai, and Junsong Pan. "QTL Mapping for Disease Resistance in Cucumber." In Compendium of Plant Genomes, 81–92. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-88647-9_7.

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Zheng, Chunfang, Khalid Y. Rashid, Sylvie Cloutier, and Frank M. You. "QTL and Candidate Genes for Flax Disease Resistance." In The Flax Genome, 121–48. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-16061-5_7.

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Taleei, A., H. Kanouni, and M. Baum. "QTL Analysis of Ascochyta Blight Resistance in Chickpea." In Communications in Computer and Information Science, 25–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-10236-3_3.

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da Silva Pereira, Guilherme, Carla Cristina da Silva, João Ricardo Bachega Feijó Rosa, Olusegun Olusesan Sobowale, Gabriel de Siqueira Gesteira, Marcelo Mollinari, and Zhao-Bang Zeng. "New Analytical Tools for Molecular Mapping of Quantitative Trait Loci in Sweetpotato." In Compendium of Plant Genomes, 69–84. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-65003-1_6.

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AbstractQuantitative trait loci(QTL) mapping is an important tool in sweetpotato research, contributing to the understanding of genetic architecture of various traits, including dry matter, nematode resistance, and flesh color. Early QTL work was carried out by using marker information alone via single marker analysis (SMA), or based on parent-specific linkage map using interval mapping (IM), composite interval mapping (CIM), and multiple interval mapping (MIM). Initially developed for inbred diploid species populations, these methods did not fully consider the complex autopolyploid, outcrossing nature of sweetpotato. Technological and methodological advances made it possible to obtain integrated, fully phased genetic maps for the crop. A random-effect MIM approach that leverages identity-by-descent based on QTL genotype conditional probabilities has been employed since with increasing power and resolution. To illustrate QTL identification in sweetpotato, we used publicly available data from ‘Beauregard’ × ‘Tanzania’ full-sib family ($$N = 315$$ N = 315 ) evaluated for flesh color in Peru. Several methods were able to detect two QTL on chromosomes 3 and 12 each for this trait in the same genomic regions. Despite the importance of such methods, there is need to extend existing models to account for multi-trait or multi-environment data and to evaluate their application in genomic-enabled prediction.
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Li, Chengdao, Sanjiv Gupta, Xiao-Qi Zhang, Sharon Westcott, Jian Yang, Robert Park, Greg Platz, Robert Loughman, and Reg Lance. "A Major QTL Controlling Adult Plant Resistance for Barley Leaf Rust." In Advance in Barley Sciences, 285–300. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-4682-4_24.

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Shahzadi, Asifa, Samra Farooq, Ali Razzaq, Fozia Saleem, Gelyn D. Sapin, Shabir Hussain Wani, and Vincent Pamugas Reyes. "Advancement in QTL Mapping to Develop Resistance Against European Corn Borer (ECB) in Maize." In Maize Improvement, 25–40. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-21640-4_2.

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Curley, J., S. C. Sim, G. Jung, S. Leong, S. Warnke, and R. E. Barker. "QTL Mapping of Gray Leaf Spot Resistance in Ryegrass, and Synteny-based Comparison with Rice Blast Resistance Genes in Rice." In Developments in Plant Breeding, 37–46. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/1-4020-2591-2_3.

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Yang, Jian, Chengdao Li, Xue Gong, Sanjiv Gupta, Reg Lance, Guoping Zhang, Rob Loughman, and Jun Zhu. "Large Population with Low Marker Density Verse Small Population with High Marker Density for QTL Mapping: A Case Study for Mapping QTL Controlling Barley Net Blotch Resistance." In Advance in Barley Sciences, 301–15. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-4682-4_25.

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Houston, R. D., A. Gheyas, A. Hamilton, D. R. Guy, A. E. Tinch, J. B. Taggart, B. J. McAndrew, C. S. Haley, and S. C. Bishop. "Detection and Confirmation of a Major QTL Affecting Resistance to Infectious Pancreatic Necrosis (IPN) in Atlantic Salmon (Salmo Salar)." In Animal Genomics for Animal Health, 199–204. Basel: KARGER, 2008. http://dx.doi.org/10.1159/000317160.

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Toffolatti, Silvia Laura, Marisol Prandato, Luca Serrati, Helge Sierotzki, Ulrich Gisi, and Annamaria Vercesi. "Evolution of Qol resistance in Plasmopara viticola oospores." In The Downy Mildews - Biology, Mechanisms of Resistance and Population Ecology, 199–206. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-94-007-1281-2_14.

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Conference papers on the topic "Resistance QTL"

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Mukiibi, R., D. Robledo, C. Peñaloza, S. Ferraresso, R. Franch, D. Bertotto, M. Freguglia, et al. "573. A major QTL affects resistance to viral nervous necrosis in farmed European seabass." In World Congress on Genetics Applied to Livestock Production. The Netherlands: Wageningen Academic Publishers, 2022. http://dx.doi.org/10.3920/978-90-8686-940-4_573.

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Calboli, F. C. F., H. Koskinen, A. Nousianen, C. Fraslin, R. D. Houston, and A. Kause. "565. Conserved QTL and chromosomal inversions affect resistance to columnaris disease in two rainbow trout populations." In World Congress on Genetics Applied to Livestock Production. The Netherlands: Wageningen Academic Publishers, 2022. http://dx.doi.org/10.3920/978-90-8686-940-4_565.

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Mirskaya, G. V., E. V. Kanash, N. V. Kocherina, N. A. Rushina, D. V. Rusakov, and Yu V. Chesnokov. "QTL MAPPING THAT DETERMINE TRAITS OF GRAIN PRODUCTIVITY IN SOFT SPRING WHEAT (TRITICUM AESTIVUM L.) UNDER DIFFERENT LEVELS OF NITROGEN NUTRITION." In The All-Russian Scientific Conference with International Participation and Schools of Young Scientists "Mechanisms of resistance of plants and microorganisms to unfavorable environmental". SIPPB SB RAS, 2018. http://dx.doi.org/10.31255/978-5-94797-319-8-527-530.

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"Exploring wheat genotype influence on microbiome-mediated take-all disease suppression." In Plant Health 2024. American Phytopathological Society, 2024. http://dx.doi.org/10.1094/aps-ph24-027.

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Take-all disease caused by Gaeumannomyces tritici, a fungal root pathogen, significantly impacts wheat production globally. Effective biocontrol for take-all is the buildup of a 2,4-diacetylphloroglucinol-producing Pseudomonas spp, which both antagonizes the pathogen and induces plant disease resistance. Previous work found that wheat genotypes vary in accumulating Pseudomonas spp in the rhizosphere, with those hosting more Pseudomonas spp being more resistant to disease. Here, we aim to identify plant genetic markers associated with this variation. In a greenhouse experiment, we grew two recombinant inbred lines (RILs) known to be segregating for their ability to support disease-suppressive Pseudomonas spp. First, each RIL was grown for three weeks, after which above-ground tissue was removed and the same RIL was re-planted into the same soil for seven cycles. Following the final cycle, we infested the soil with the take-all pathogen to assess take-all severity. Our preliminary results will include disease data from this inoculation effort. We expect that soil from specific RILs will display better defense mechanisms against take-all. Next, we will collect rhizosphere soil samples to characterize bacterial and fungal symbionts, correlating microbial community profiles with disease data against quantitative trait locus (QTL) maps. Understanding how wheat genotypes accumulate protective populations of Pseudomonas and other soil microbes can provide new tools for managing an important disease of this staple food crop.
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Amromin, Eduard, Svetlana Kovinskaya, Marina Mizina, and Igor Mizine. "Quasi-Linear Theory of Ship Wave Resistance and CFD Analysis of Ship’s Environmental Impact." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45440.

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Quasi-linear theory (QLT) introduces corrections to the Havelock integral and makes it possible to operate with realistic wave amplitudes and length into framework of linear theory. These corrections for wave amplitude and length are based on implicit employment of the model 2D problems for nonlinear waves of highest magnitude (Stokes waves). There is both description of algorithms and comparison with towing test results for diverse ships here. A substantially novel (and environmentally important) aspect of this paper is application of QLT to computation of ship wave resistance in shallow waters.
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McCoy, Terry H., and Jeffrey Thomas. "SSC Resistance of QT-900 and QT-1000 Coiled Tubing." In SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition. Society of Petroleum Engineers, 2006. http://dx.doi.org/10.2118/99557-ms.

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Santos, Jessika Teodoro, Naiany Pereira Silva, Rizia Rocha Silva, Vitor Alves Marques, Rafael Ribeiro Alves, Nathan Muci Aguiar Damasio, and Carlos Alexandre Vieira. "Evaluation of quality of life of women breast cancer survivors who received resistance training for 12 months." In Brazilian Breast Cancer Symposium 2024, 83. Mastology, 2024. http://dx.doi.org/10.29289/259453942024v34s1083.

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Objective: The study aimed to assess the impact of a 12-month resistance training (RT) protocol on the quality of life (QoL) of woman breast cancer (BC) survivors. Methodology: This is an experimental study, lasting 12 months and involving 10 women (58.80±6.94 years) BC survivors. QoL was evaluated using the FACT B+4 (Functional Assessment of Cancer Therapy – BC + Arm Subscale) composed of the domains: physical well-being (PWB), social/family well-being (SWB), well- -being emotional (EWB), functional well-being (FWB), BC specific aspects (BCS), Trial Outcomes Index (TOI), FACT-B, and FACT-G. To analyze the two dependent measurements (pre- and post-intervention), we used the paired student t-test (parametric data) described as mean and standard error (SE) and the Wilcoxon test (non-parametric) described as median and SE. Results: For QoL, there was a significant difference for SWB with an improvement of 6.10 (SE 2.11) points (t(9)=2.883, p=0.018; d=1.14 “large”) and FWB improvement of 7.60 (SE 2.77) points (t(9)=2.736, p=0.023; d=0.86 “large”). As for TOI, FACT-G, and FACT-B, there was a significant increase post-training, with gains of 13.60 (SE 4.02), 17.10 (SE 5.07), and 21.90 (SE 6.31) points, respectively, with significant differences for TOI (t(9)=3.376, p=0.008; d=1.06 “large”), FACT-G (t(9)=3.372, p=0.009; d=1.06 “large”), and FACT-B (t(9)=3.468, p=0.007; d=1.09 “large”). The Wilcoxon test indicated an improvement in BCS after the intervention, with a median of 4.00 (SE 2.14) points (W=3.500, p=0.027, rB=0.84 “large”). Conclusion: RT after 12 months of intervention is significantly beneficial in improving the QoL of women BC survivors.
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McCoy, Terry H. "SSC Resistance of QT-900 Coiled Tubing." In SPE/ICoTA Coiled Tubing Conference and Exhibition. Society of Petroleum Engineers, 2005. http://dx.doi.org/10.2118/93786-ms.

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Taleei, Alireza, Homayoun Kanouni, Michael Baum, Seyed Ali Peyghambari, Seyed Mahmood Okhovat, and Mathew Abang. "Identification and Mapping of QTLs for Resistance to Ascochyta Blight (Pathotype III) in Chickpea." In 2008 Second International Conference on Future Generation Communication and Networking (FGCN). IEEE, 2008. http://dx.doi.org/10.1109/fgcn.2008.184.

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Okada, Masato, Shin Terada, Yuki Kataoka, Takeshi Kihara, Takuya Miura, and Masaaki Otsu. "Burnishing Characteristics of Sliding Burnishing Process With Active Rotary Tool Targeting Stainless Steel." In JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/lemp2020-8515.

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Abstract This paper investigates the burnishing characteristics of a developed sliding burnishing method with active rotary tool targeting a martensitic stainless steel. Two types of martensitic stainless steel, annealing (AN) stainless steel and quenching and tempering (QT) stainless steel, were targeted. The burnishing characteristics evaluated included surface roughness, profile, microstructure, subsurface hardness, bending property, and corrosion resistance. A sufficiently smooth surface, approximately Ra = 0.1 μm and Ra = 0.025 μm in both materials, respectively, was obtained using the developed burnishing method; irregular profile smoothing occurred due to the material flow of the subsurface. The subsurface hardness increased at a depth of 40 μm or more when using the developed burnishing method on the AN material, but no effect was observed for the QT material. Moreover, the bending yield point and strength of the sheet shape workpiece increased by applying the burnishing process to the AN material. The influence of the burnishing process on the bending properties was also observed for the QT material. Corrosion resistance can be improved through the burnishing process.
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Reports on the topic "Resistance QTL"

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Santa S, Juan David, Jhon Alexander Berdugo C., Teresa Mosquera V., Nubia Liliana Cely, Mauricio Soto S., and Carlos H. Galeano M. QTL analysis for late blight resistance in an Andean Tetraploid potato population. Corporación Colombiana de Investigación Agropecuaria - AGROSAVIA, 2016. http://dx.doi.org/10.21930/agrosavia.poster.2016.49.

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Un problema fitosanitario importante en la producción de papa en Colombia es el tizón tardío, causado por el oomiceto Phythopthora infestans (Mont) de Bary. Este problema fitosanitario puede alcanzar hasta el 100% de las pérdidas en el campo. En este momento, la producción de papa en Colombia cuenta con poca resistencia cultivares y dependientes del manejo de enfermedades principalmente en el uso de fungicidas, por lo tanto el control químico representa un impacto negativo en el medio ambiente y el consumidor. Por lo general, múltiples genes o QTL controlan la resistencia cuantitativa a las enfermedades. Para resistencia hasta el tizón tardío, un mapa de consenso reportó 24 meta QTL agrupando 144 QTLs reportados previamente. Los avances en las plataformas de genotipado, como el Innium Potato Array, han hecho posible mapeo genético de alta densidad en genotipos tetraploides de diversos caracteres con interés agronómico. A pesar de estos avances, la investigación sobre la genética de la papa tetraploide y específicamente sobre la resistencia a enfermedades es limitada. Por lo tanto, los objetivos del presente estudio fueron: construir un mapa de ligamiento y para mapear QTL de resistencia a P. infestans usando la cruz F1 RN × 2384.
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Wisniewski, Michael E., Samir Droby, John L. Norelli, Noa Sela, and Elena Levin. Genetic and transcriptomic analysis of postharvest decay resistance in Malus sieversii and the characterization of pathogenicity effectors in Penicillium expansum. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7600013.bard.

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Blue mold of apple caused by Penicilliumexpansumis a major postharvest disease. Selection for postharvest disease resistance in breeding programs has been ignored in favor of fruit quality traits such as size, color, taste, etc. The identification of postharvest disease resistance as a heritable trait would represent a significant accomplishment and has not been attempted in apple. Furthermore, insight into the biology of the pathogenicity of P. expansumin apple could provide new approaches to postharvest decay management. Hypothesis: Postharvest resistance of apple to P. expansumcan be mapped to specific genetic loci and significant quantitative-trait-loci (QTLs) can be identified that account for a major portion of the population variance. Susceptibility of apple fruit to P. expansumis dependent on the ability of the pathogen to produce LysM effectors that actively suppress primary and/or secondary resistance mechanisms in the fruit. Objectives: 1) Identify QTL(s) and molecular markers for blue mold resistance in GMAL4593 mapping population (‘Royal Gala’ X MalussieversiiPI613981), 2) Characterize the transcriptome of the host and pathogen (P. expansum) during the infection process 3) Determine the function of LysM genes in pathogenicity of P. expansum. Methods: A phenotypic evaluation of blue mold resistance in the GMAL4593 mapping population, conducted in several different years, will be used for QTL analysis (using MapQTL 6.0) to identify loci associated with blue mold resistance. Molecular markers will be developed for the resistance loci. Transcriptomic analysis by RNA-seq will be used to conduct a time course study of gene expression in resistant and susceptible apple GMAL4593 genotypes in response to P. expansum, as well as fungal responses to both genotypes. Candidate resistance genes identified in the transcriptomic study and or bioinformatic analysis will be positioned in the ‘Golden Delicious’ genome to identify markers that co-locate with the identified QTL(s). A functional analysis of LysM genes on pathogenicity will be conducted by eliminating or reducing the expression of individual effectors by heterologous recombination and silencing technologies. LysMeffector genes will also be expressed in a yeast expression system to study protein function. Expected Results: Identification of postharvest disease resistance QTLs and tightly-linked genetic markers. Increased knowledge of the role of effectors in blue mold pathogenic
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Levin, Ilan, John Thomas, Moshe Lapidot, Desmond McGrath, and Denis Persley. Resistance to Tomato yellow leaf curl virus (TYLCV) in tomato: molecular mapping and introgression of resistance to Australian genotypes. United States Department of Agriculture, October 2010. http://dx.doi.org/10.32747/2010.7613888.bard.

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Tomato yellow leaf curl virus (TYLCV) is one of the most devastating viruses of cultivated tomatoes. Although first identified in the Mediterranean region, it is now distributed world-wide. Sequence analysis of the virus by the Australian group has shown that the virus is now present in Australia. Despite the importance of the disease and extensive research on the virus, very little is known about the resistance genes (loci) that determine host resistance and susceptibility to the virus. A symptom-less resistant line, TY-172, was developed at the Volcani Center which has shown the highest resistance level among all tested varieties. Preliminary results show that TY-172 is a good candidate to confer resistance to both TYLCV and to Tomato leaf curl virus (ToLCV) in Queensland conditions. Furthermore, Segregation analysis has previously indicated that the resistance is determined by 2-3 genes. In this proposal we aimed to substantiate that TY-172 can contribute to resistance breeding against TYLCV in Queensland, to develop DNA markers to advance such resistance breeding in both Israel and Queensland, and to exploit these markers for resistant breeding in Australian and Israeli lines. To map quantitative trait loci (QTLs) controlling TYLCVresistance in TY172, appropriate segregating populations were analyzed using 69 polymorphic DNA markers spanning the entire tomato genome. Results show that TYLCV resistance in TY172 is controlled by a previously unknown major QTL, originating from the resistant line, and four additional minor QTLs. The major QTL, termed Ty-5, maps to chromosome 4 and accounts for 39.7-to-46.6% of the variation in symptom severity among segregating plants (LOD score: 33-to-35). The minor QTLs, originated either from the resistant or susceptible parents, were mapped to chromosomes 1, 7, 9 and 11, and contributed 12% to the variation in symptom severity in addition to Ty-5. Further analysis of parental lines as well as large F₁, BC₁F₁, F₂ and BC₁F₂ populations originating from crosses carried out, in reciprocal manner, between TY172 and the susceptible processing line M-82 (LA3475) during spring-summer 2010, indicated that: (1) the minor QTLs we have previously identified are in effect not reproducible, (2)Ty-5 alone can yield highly resistant plants with practically no extra-chromosomal effects, and (3) the narrow-sense heritability estimate of resistance levels, attributed to additive factors responsive to selection, does not significantly deviate from 1. All of these results point to Ty-5 as the sole resistance locus in TY172 thus significantly increasing the likelihood of its successful molecular dissection. The DNA markers developed during the course of this study were transferred together with the TY172 genotype to Queensland. TY172 was crossed to a panel of Australian genotypes and the resulting populations were subjected to segregation analysis. Results showed that resistant locus, Ty-5, is highly reproducible in the Australian conditions as well. The Australian group was also able to make improvements to the marker assays by re-designing primer pairs to provide more robust PCR fragments. The Ty-5 locus has now been introgressed into elite Australian germplasm and selection for TYLCV resistance has begun. Cumulatively, our results show that Ty-5 can be effectively used, together with the TY172 genotype to expedite TYLCV resistance breeding and improve our understanding of the genetics that underline the response of tomato to TYLCV. Contributions to agriculture include: (1) the development of tools for more efficient resistance breeding, allowing the incorporation of resistance to local tomato varieties in Australia, Israel and elsewhere; and (2) establish a solid framework for a future attempt to clone the genes that encode such resistance. The latter will enable to decipher the resistance mechanisms that could be applied to other geminiviruses in tomato and possibly in other plant species.
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Simon, James, and Yigal Cohen. Basil gene pool enrichment for Downy Mildew resistance and QTL development using genotyping by sequencing. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604273.bard.

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Santa Sepúlveda, Juan David, Jhon Berdugo Cely, Mauricio Soto Suárez, Teresa Mosquera, and Carlos Galeano. A genetic linkage map of tetraploid potato (Solanum tuberosum L.) for Phytophthora infestans and Tecia solanivora quantitative resistance. Corporación Colombiana de Investigación Agropecuaria - AGROSAVIA, 2016. http://dx.doi.org/10.21930/agrosavia.poster.2016.28.

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Los avances en la selección asistida de selección molecular y marcadores han sido limitados debido a a los problemas de alta heterocigosis y ploidía en el grupo de papa Andigenum (adg). Recientemente, Se han desarrollado mapas basados ??en SNP de alta densidad para papa diploide y tetraploide. Además, los modelos estadísticos que incluyen la dosificación alélica, están mejorando la vinculación mapeo y análisis de QTL en papa autotetraploide (Hackett et al., 2014). Estos enfoques han facilitado el análisis de QTL de rasgos agronómicos como resistencia a P. infestans (Massa et al., 2015). La producción de papa en Colombia está afectada por el tizón tardío (P. infestans) y guatemalteco la polilla del tubérculo de la papa (T. solanivora) provoca pérdidas de hasta el 100% en el campo y el almacenamiento. Por lo tanto, en para comprender los factores genéticos que subyacen a la resistencia a P. infestans y T. solanivora, el objetivo principal de esta investigación es construir un mapa genético de alta saturación de SNP población tetraploide que se utilizará para mapear la resistencia QTL.
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David, Lior, Yaniv Palti, Moshe Kotler, Gideon Hulata, and Eric M. Hallerman. Genetic Basis of Cyprinid Herpes Virus-3 Resistance in Common Carp. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7592645.bard.

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The goal of this project was to provide scientific and technical basis for initiating the development of breeding protocols using marker assisted selection for viral disease resistance in common carp. The specific objectives were: 1) Establishing families and characterizing the phenotypic and genetic variation of viral resistance; 2) Measuring the dynamics of immune response and developing a method to measure the long term immune memory; 3) Developing markers and generating a new genetic linkage map, which will enable initial QTL mapping; and, 4) Identifying genetic linkage of markers and candidate genes (like MHC and TLRs) with resistance to CyHV-3. The common carp is an important farmed freshwater fish species in the world. Edible carp is second only to tilapia in Israeli aquaculture production and ornamental carp (koi) is an important product in both the US and Israel. Carp industries worldwide have recently suffered enormous economic damage due to a viral disease caused by Cyprinid herpes virus 3 (CyHV-3). Aside from preventative measures, a sustainable solution to this problem will be to establish a genetic improvement program of the resistance of fish to the pathogen. The aims of the project was to take the necessary first steps towards that. The differences in survival rates after infection with CyHV-3 virus among 20 families from six types of crosses between three carp lines (two commercial lines and one wild-type carp) revealed that the wild-type carp and its crosses had a much-improved survival over the crosses of the commercial lines themselves. These crosses set the starting point for breeding of commercial strains with improved resistance. Resistant fish had lower antibody titer against the virus suggesting that resistance might depend more on the innate immunity. A set of 500 microsateliite markers was developed and the markers are currently being used for generating a genetic linkage map for carp and for identifying disease resistance QTL. Fourteen candidate immune genes, some of which were duplicated, were cloned from the carp and SNP markers were identified in them. The expression of these genes varied between tissues and suggested functional divergence of some duplicated genes. Initial association between CyHV-3 resistance and one of the genes was found when SNP alleles in these genes were tested for their segregation between susceptible and resistant progeny. The results of this project have implications to the development of viral resistant commercial carp strains and effective immunization against this aggressive disease. The genetic and immunological knowledge accumulated in this project will not only promote carp and koi production but will also contribute to a broader understanding of fish immunogenetics.
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Dubcovsky, Jorge, Tzion Fahima, Tamar Krugman, and Tyson Howell. Positional cloning of a rye QTL responsible for water stress resistance in wheat based on radiation mapping and comparative genomics. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604265.bard.

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Lapidot, Moshe, and Vitaly Citovsky. molecular mechanism for the Tomato yellow leaf curl virus resistance at the ty-5 locus. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604274.bard.

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Tomato yellow leaf curl virus (TYLCV) is a major pathogen of tomato that causes extensive crop loss worldwide, including the US and Israel. Genetic resistance in the host plant is considered highly effective in the defense against viral infection in the field. Thus, the best way to reduce yield losses due to TYLCV is by breeding tomatoes resistant or tolerant to the virus. To date, only six major TYLCV-resistance loci, termed Ty-1 to Ty-6, have been characterized and mapped to the tomato genome. Among tomato TYLCV-resistant lines containing these loci, we have identified a major recessive quantitative trait locus (QTL) that was mapped to chromosome 4 and designated ty-5. Recently, we identified the gene responsible for the TYLCV resistance at the ty-5 locus as the tomato homolog of the gene encoding messenger RNA surveillance factor Pelota (Pelo). A single amino acid change in the protein is responsible for the resistant phenotype. Pelo is known to participate in the ribosome-recycling phase of protein biosynthesis. Our hypothesis was that the resistant allele of Pelo is a “loss-of-function” mutant, and inhibits or slows-down ribosome recycling. This will negatively affect viral (as well as host-plant) protein synthesis, which may result in slower infection progression. Hence we have proposed the following research objectives: Aim 1: The effect of Pelota on translation of TYLCV proteins: The goal of this objective is to test the effect Pelota may or may not have upon translation of TYLCV proteins following infection of a resistant host. Aim 2: Identify and characterize Pelota cellular localization and interaction with TYLCV proteins: The goal of this objective is to characterize the cellular localization of both Pelota alleles, the TYLCV-resistant and the susceptible allele, to see whether this localization changes following TYLCV infection, and to find out which TYLCV protein interacts with Pelota. Our results demonstrate that upon TYLCV-infection the resistant allele of pelota has a negative effect on viral replication and RNA transcription. It is also shown that pelota interacts with the viral C1 protein, which is the only viral protein essential for TYLCV replication. Following subcellular localization of C1 and Pelota it was found that both protein localize to the same subcellular compartments. This research is innovative and potentially transformative because the role of Peloin plant virus resistance is novel, and understanding its mechanism will lay the foundation for designing new antiviral protection strategies that target translation of viral proteins. BARD Report - Project 4953 Page 2
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Levin, Ilan, John W. Scott, Moshe Lapidot, and Moshe Reuveni. Fine mapping, functional analysis and pyramiding of genes controlling begomovirus resistance in tomato. United States Department of Agriculture, November 2014. http://dx.doi.org/10.32747/2014.7594406.bard.

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Abstract. Tomato yellow leaf curl virus (TYLCV), a monopartitebegomovirus, is one of the most devastating viruses of cultivated tomatoes and poses increasing threat to tomato production worldwide. Because all accessions of the cultivated tomato are susceptible to these viruses, wild tomato species have become a valuable resource of resistance genes. QTL controlling resistance to TYLCV and other begomoviruses (Ty loci) were introgressed from several wild tomato species and mapped to the tomato genome. Additionally, a non-isogenic F₁diallel study demonstrated that several of these resistance sources may interact with each other, and in some cases generate hybrid plants displaying lower symptoms and higher fruit yield compared to their parental lines, while their respective resistance genes are not necessarily allelic. This suggests that pyramiding genes originating from different resistance sources can be effective in obtaining lines and cultivars which are highly resistant to begomoviruses. Molecular tools needed to test this hypothesis have been developed by our labs and can thus significantly improve our understanding of the mechanisms of begomovirus resistance and how to efficiently exploit them to develop wider and more durable resistance. Five non-allelic Ty loci with relatively major effects have been mapped to the tomato genome using molecular DNA markers, thereby establishing tools for efficient marker assisted selection, pyramiding of multiple genes, and map based gene cloning: Ty-1, Ty-2, Ty-3, Ty-4, and ty-5. This research focused on Ty-3 and Ty-4 due to their broad range of resistance to different begomoviruses, including ToMoV, and on ty-5 due to its exceptionally high level of resistance to TYLCV and other begomoviruses. Our aims were: (1) clone Ty-3, and fine map Ty-4 and Ty-5 genes, (2)introgress each gene into two backgroundsand develop semi isogenic lines harboring all possible combinations of the three genes while minimizing linkage-drag, (3) test the resulting lines, and F₁ hybrids made with them, for symptom severity and yield components, and (4) identify and functionally characterize candidate genes that map to chromosomal segments which harbor the resistance loci. During the course of this research we have: (1) found that the allelic Ty-1 and Ty-3 represent two alternative alleles of the gene coding DFDGD-RDRP; (2) found that ty-5is highly likely encoded by the messenger RNA surveillance factor PELOTA (validation is at progress with positive results); (3) continued the map-based cloning of Ty-4; (4) generated all possible gene combinations among Ty-1, Ty-3 and ty-5, including their F₁ counterparts, and tested them for TYLCV and ToMoV resistance; (5) found that the symptomless line TY172, carrying ty-5, also carries a novel allele of Ty-1 (termed Ty-1ⱽ). The main scientific and agricultural implications of this research are as follows: (1) We have developed recombination free DNA markers that will substantially facilitate the introgression of Ty-1, Ty-3 and ty-5 as well as their combinations; (2) We have identified the genes controlling TYLCV resistance at the Ty-1/Ty-3 and ty-5 loci, thus enabling an in-depth analyses of the mechanisms that facilitate begomovirus resistance; (3) Pyramiding of Ty resistance loci is highly effective in providing significantly higher TYLCV resistance.
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Joel, Daniel M., Steven J. Knapp, and Yaakov Tadmor. Genomic Approaches for Understanding Virulence and Resistance in the Sunflower-Orobanche Host-Parasite Interaction. United States Department of Agriculture, August 2011. http://dx.doi.org/10.32747/2011.7592655.bard.

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Oroginal Objectives: (i) identify DNA markers linked to the avirulence (Avr) locus and locate the Avr locus through genetic mapping with an inter-race Orobanche cumana population; (ii) develop high-throughput fingerprint DNA markers for genotypingO. cumana races; (iii) identify nucleotide binding domain leucine rich repeat (NB-LRR) genes encoding R proteins conferring resistance to O. cumana in sunflower; (iv) increase the resolution of the chromosomal segment harboring Or₅ and related R genes through genetic and physical mapping in previously and newly developed mapping populations of sunflower; and (v) develop high-throughput DNA markers for rapidly and efficiently identifying and transferring sunflower R genes through marker-assisted selection. Revisions made during the course of project: Following changes in O. cumana race distribution in Israel, the newly arrived virulent race H was chosen for further analysis. HA412-HO, which was primarily chosen as a susceptible sunflower cultivar, was more resistant to the new parasite populations than var. Shemesh, thus we shifted sunflower research into analyzing the resistance of HA412-HO. We exceeded the deliverables for Objectives #3-5 by securing funding for complete physical and high-density genetic mapping of the sunflower genome, in addition to producing a complete draft sequence of the sunflower genome. We discovered limited diversity between the parents of the O. cumana population developed for the mapping study. Hence, the developed DNA marker resources were insufficient to support genetic map construction. This objective was beyond the scale and scope of the funding. This objective is challenging enough to be the entire focus of follow up studies. Background to the topic: O. cumana, an obligate parasitic weed, is one of the most economically important and damaging diseases of sunflower, causes significant yield losses in susceptible genotypes, and threatens production in Israel and many other countries. Breeding for resistance has been crucial for protecting sunflower from O. cumana, and problematic because new races of the pathogen continually emerge, necessitating discovery and deployment of new R genes. The process is challenging because of the uncertainty in identifying races in a genetically diverse parasite. Major conclusions, solutions, achievements: We developed a small collection of SSR markers for genetic mapping in O. cumana and completed a diversity study to lay the ground for objective #1. Because DNA sequencing and SNPgenotyping technology dramatically advanced during the course of the study, we recommend shifting future work to SNP discovery and mapping using array-based approaches, instead of SSR markers. We completed a pilot study using a 96-SNP array, but it was not large enough to support genetic mapping in O.cumana. The development of further SNPs was beyond the scope of the grant. However, the collection of SSR markers was ideal for genetic diversity analysis, which indicated that O. cumanapopulations in Israel considerably differ frompopulations in other Mediterranean countries. We supplied physical and genetic mapping resources for identifying R-genes in sunflower responsible for resistance to O. cumana. Several thousand mapped SNP markers and a complete draft of the sunflower genome sequence are powerful tools for identifying additional candidate genes and understanding the genomic architecture of O. cumana-resistanceanddisease-resistance genes. Implications: The OrobancheSSR markers have utility in sunflower breeding and genetics programs, as well as a tool for understanding the heterogeneity of races in the field and for geographically mapping of pathotypes.The segregating populations of both Orobanche and sunflower hybrids are now available for QTL analyses.
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