Articles de revues : « Resistance QTL »

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Drake-Stowe, Katherine, Nicolas Bakaher, Simon Goepfert, Berangere Philippon, Regis Mark, Paul Peterson et Ramsey S. Lewis. « Multiple Disease Resistance Loci Affect Soilborne Disease Resistance in Tobacco (Nicotiana tabacum) ». Phytopathology® 107, n^o 9 (septembre 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, et Viktor Korzun. « Marker-Assisted Selection for Disease Resistance in Wheat and Barley Breeding ». Phytopathology® 102, n^o 6 (juin 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 et 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, n^o 1 (janvier 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 et Claudia Teixeira Guimaraes. « Quantitative Trait Loci and Resistance Gene Analogs Associated with Maize White Spot Resistance ». Plant Disease 101, n^o 1 (janvier 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, et Conxita Royo. « Dissecting the Genetic Architecture of Leaf Rust Resistance in Wheat by QTL Meta-Analysis ». Phytopathology® 105, n^o 12 (décembre 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 et 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, n^o 1 (15 juin 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, n^o 2 (5 novembre 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 et J. M. Bonman. « Barley Stripe Rust Resistance QTL : Development and Validation of SNP Markers for Resistance to Puccinia striiformis f. sp. hordei ». Phytopathology® 106, n^o 11 (novembre 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 et Chawade. « QTL Mapping and Transcriptome Analysis to Identify Differentially Expressed Genes Induced by Septoria Tritici Blotch Disease of Wheat ». Agronomy 9, n^o 9 (4 septembre 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 et Allen Van Deynze. « Genetic Analysis of Resistance to Multiple Isolates of Phytophthora capsici and Linkage to Horticultural Traits in Bell Pepper ». HortScience 54, n^o 7 (juillet 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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Yang, Zhuping, Jeannie Gilbert, George Fedak et Daryl J. Somers. « Genetic characterization of QTL associated with resistance to Fusarium head blight in a doubled-haploid spring wheat population ». Genome 48, n^o 2 (1 avril 2005) : 187–96. http://dx.doi.org/10.1139/g04-104.

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Fusarium head blight (FHB) is one of the most important fungal wheat diseases worldwide. Understanding the genetics of FHB resistance is the key to facilitating the introgression of different FHB resistance genes into adapted wheat. The objectives of the present study were to detect and map quantitative trait loci (QTL) associated with FHB resistance genes and characterize the genetic components of the QTL in a doubled-haploid (DH) spring wheat population using both single-locus and two-locus analysis. A mapping population, consisting of 174 DH lines from the cross between DH181 (resistant) and AC Foremost (susceptible), was evaluated for type I resistance to initial infection during a 2-year period in spray-inoculated field trials, for Type II resistance to fungal spread within the spike in 3 greenhouse experiments using single-floret inoculation, and for resistance to kernel infection in a 2001 field trial. One-locus QTL analysis revealed 7 QTL for type I resistance on chromosome arms 2DS, 3AS, 3BS, 3BC (centromeric), 4DL, 5AS, and 6BS, 4 QTL for type II resistance on chromosomes 2DS, 3BS, 6BS, and 7BL, and 6 QTL for resistance to kernel infection on chromosomes 1DL, 2DS, 3BS, 3BC, 4DL, and 6BS. Two-locus QTL analysis detected 8 QTL with main effects and 4 additive by additive epistatic interactions for FHB resistance and identified novel FHB resistance genes for the first time on chromosomes 1DL, 4AL, and 4DL. Neither significant QTL by environment interactions nor epistatic QTL by environment interactions were found for either type I or type II resistance. The additive effects of QTL explained most of the phenotypic variance for FHB resistance. Marker-assisted selection for the favored alleles at multiple genomic regions appears to be a promising tool to accelerate the introgression and pyramiding of different FHB resistance genes into adapted wheat genetic backgrounds.Key words: Triticum aestivum, Fusarium graminearum, microsatellite, additive effect, additive by additive epistatic effect.

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Yu, J. B., G. H. Bai, W. C. Zhou, Y. H. Dong et F. L. Kolb. « Quantitative Trait Loci for Fusarium Head Blight Resistance in a Recombinant Inbred Population of Wangshuibai/Wheaton ». Phytopathology® 98, n^o 1 (janvier 2008) : 87–94. http://dx.doi.org/10.1094/phyto-98-1-0087.

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Use of diverse sources of Fusarium head blight (FHB)-resistant germplasm in breeding may significantly improve wheat resistance to FHB. Wangshuibai is an FHB-resistant Chinese landrace unrelated to cv. Sumai 3, the most commonly used FHB-resistant source. In all, 139 F6 recombinant inbred lines were developed from a cross between Wangshuibai and an FHB-susceptible cultivar, Wheaton, to map quantitative trait loci (QTL) for wheat resistance to initial infection (type I resistance), spread of FHB symptoms within a spike (type II resistance), and deoxynivalenol (DON) accumulation (type III resistance) in infected grain. The experiments were conducted in a greenhouse at Manhattan, KS from 2003 to 2005. More than 1,300 simple-sequence repeat and amplified fragment length polymorphism markers were analyzed in this population. Five QTL for type I resistance were detected on chromosomes 3AS, 3BS, 4B, 5AS, and 5DL after spray inoculation; seven QTL for type II resistance were identified on chromosomes 1A, 3BS, 3DL, 5AS, 5DL, and 7AL after point inoculation; and seven QTL for type III resistance were detected on chromosomes 1A, 1BL, 3BS, 5AS, 5DL, and 7AL with the data from both inoculation methods. These QTL jointly explained up to 31.7, 64, and 52.8% of the phenotypic variation for the three types of FHB resistance, respectively. The narrow-sense heritabilities were low for type I resistance (0.37 to 0.41) but moderately high for type II resistance (0.45 to 0.61) and type III resistance (0.44 to 0.67). The QTL on the distal end of 3BS, 5AS, and 5DL contributed to all three types of resistance. Two QTL, on 7AL and 1A, as well as one QTL near the centromere of 3BS (3BSc), showed effects on both type II and type III resistance. Selection for type II resistance may simultaneously improve type I and type III resistance as well. The QTL for FHB resistance identified in Wangshuibai have potential to be used to pyramid FHB-resistance QTL from different sources.

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Zhang, Ningwen W., Koen Pelgrom, Rients E. Niks, Richard G. F. Visser et Marieke J. W. Jeuken. « Three Combined Quantitative Trait Loci from Nonhost Lactuca saligna Are Sufficient to Provide Complete Resistance of Lettuce Against Bremia lactucae ». Molecular Plant-Microbe Interactions® 22, n^o 9 (septembre 2009) : 1160–68. http://dx.doi.org/10.1094/mpmi-22-9-1160.

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The nonhost resistance of wild lettuce (Lactuca saligna) to downy mildew (Bremia lactucae) is based on at least 15 quantitative trait loci (QTL), each effective at one or more plant developmental stages. We used QTL pyramiding (stacking) to determine how many of these QTL from L. saligna are sufficient to impart complete resistance towards B. lactucae to cultivated lettuce, L. sativa. The alleles of four of the most promising QTL, rbq4, rbq5, rbq6+11, and rbq7 are effective at both the young and adult plant stages. Lines with these four QTL in all possible combinations were generated by crossing the respective backcross inbred lines (BIL). Using the 11 resulting lines (combiBIL), we determined that combinations of three QTL, rbq4, rbq5, and rbq6+11, led to increased levels of resistance; however, one QTL, rbq7, did not add to the resistance level when combined with the other QTL. One line, tripleBIL268, which contains the three QTL rbq4, rbq5, and rbq6+11, was completely resistant to B. lactucae at the young plant stage. This suggests that these three QTL are sufficient to confer the complete resistance of the nonhost L. saligna and any additional QTL in L. saligna are redundant. Histological analysis of B. lactucae infection in L. saligna, the BIL, and the combiBIL 48 h after inoculation revealed different microscopical phenotypes of resistance. The QTL differed with respect to the stage of the infection process with which they interfered.

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Crawford, Allan M., Sin H. Phua, John C. McEwan, Ken G. Dodds, Craig C. Wright, Chris A. Morris, Stuart A. Bisset et Richard S. Green. « Finding disease resistance QTL in sheep ». Animal Biotechnology 8, n^o 1 (avril 1997) : 13–22. http://dx.doi.org/10.1080/10495399709525862.

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Iimura, Kazunari, Kimihisa Tasaki, Yoshiko Nakazawa et Masayuki Amagai. « QTL analysis of strawberry anthracnose resistance ». Breeding Research 15, n^o 3 (2013) : 90–97. http://dx.doi.org/10.1270/jsbbr.15.90.

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Liu, L., Y. D. Zhang, H. Y. Li, Y. Q. Bi, L. J. Yu, X. M. Fan, J. Tan, D. P. Jeffers et M. S. Kang. « QTL Mapping for Gray Leaf Spot Resistance in a Tropical Maize Population ». Plant Disease 100, n^o 2 (février 2016) : 304–12. http://dx.doi.org/10.1094/pdis-08-14-0825-re.

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A tropical gray leaf spot (GLS)-resistant line, YML 32, was crossed to a temperate GLS-susceptible line, Ye 478, to produce an F2:3 population for the identification of quantitative trait loci (QTL) associated with resistance to GLS. The population was evaluated for GLS disease resistance and flowering time at two locations in Yunnan province. Seven QTL using GLS disease scores and six QTL using flowering time were identified on chromosomes 2, 3, 4, 5, and 8 in the YML 32 × Ye 478 maize population. All QTL, except one identified on chromosome 2 using flowering time, were overlapped with the QTL for GLS disease scores. The results indicated that QTL for flowering time in this population strongly corresponded to QTL for GLS resistance. Among the QTL, qRgls.yaas-8-1/qFt.yaas-8 with the largest genetic effect accounted for 17.9 to 18.1 and 11.0 to 21.42% of variations for GLS disease scores and flowering time, respectively, and these should be very useful for improving resistance to GLS, especially in subtropical maize breeding programs. The QTL effects for resistance to GLS were predominantly additive in nature, with a dominance effect having been found for two QTL on the basis of joint segregation genetic analysis and QTL analysis.

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Francki, M. G., M. Shankar, E. Walker, R. Loughman, H. Golzar et H. Ohm. « New Quantitative Trait Loci in Wheat for Flag Leaf Resistance to Stagonospora nodorum Blotch ». Phytopathology® 101, n^o 11 (novembre 2011) : 1278–84. http://dx.doi.org/10.1094/phyto-02-11-0054.

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Stagonospora nodorum blotch (SNB) is a significant disease in some wheat-growing regions of the world. Resistance in wheat to Stagonospora nodorum is complex, whereby genes for seedling, flag leaf, and glume resistance are independent. The aims of this study were to identify alternative genes for flag leaf resistance, to compare and contrast with known quantitative trait loci (QTL) for SNB resistance, and to determine the potential role of host-specific toxins for SNB QTL. Novel QTL for flag leaf resistance were identified on chromosome 2AS inherited from winter wheat parent ‘P92201D5’ and chromosome 1BS from spring wheat parent ‘EGA Blanco’. The chromosomal map position of markers associated with QTL on 1BS and 2AS indicated that they were unlikely to be associated with known host–toxin insensitivity loci. A QTL on chromosome 5BL inherited from EGA Blanco had highly significant association with markers fcp001 and fcp620 based on disease evaluation in 2007 and, therefore, is likely to be associated with Tsn1-ToxA insensitivity for flag leaf resistance. However, fcp001 and fcp620 were not associated with a QTL detected based on disease evaluation in 2008, indicating two linked QTL for flag leaf resistance with multiple genes residing on 5BL. This study identified novel QTL and their effects in controlling flag leaf SNB resistance.

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Malihipour, Ali, Jeannie Gilbert, George Fedak, Anita Brûlé-Babel et Wenguang Cao. « Mapping the A Genome for QTL Conditioning Resistance to Fusarium Head Blight in a Wheat Population with Triticum timopheevii Background ». Plant Disease 101, n^o 1 (janvier 2017) : 11–19. http://dx.doi.org/10.1094/pdis-02-16-0144-re.

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Development and use of resistant wheat cultivars is the most practical and economical approach for the control of Fusarium head blight (FHB). In the present study, a population of recombinant inbred lines derived from the cross between ‘AC Brio’ (a Canadian bread wheat cultivar moderately susceptible to FHB) and ‘TC 67’ (an FHB-resistant cultivar derived from Triticum timopheevii) was used to map quantitative trait loci (QTL) for FHB resistance using microsatellite molecular markers. Multiple interval mapping detected several QTL for FHB resistance on the chromosomes 5AL and 6A. The QTL detected in the marker interval of cfd6.1-barc48 on chromosome 5AL explained 10.9, 5.2, and 7.8% of phenotypic variation for disease incidence (type I resistance), disease severity (a combination of type I and type II resistance), and Fusarium-damaged kernels (FDK) (type IV resistance) under field conditions, respectively. The second QTL mapped to 5AL, in the marker interval of cfd39-cfa2185, explained 19.4 and 20.6% of phenotypic variation for FDK under field conditions and disease severity in the greenhouse (type II resistance), respectively. The QTL located on chromosome 6A conferred resistance to disease incidence and severity under field conditions and to disease severity in the greenhouse, explaining 6.8 to 11.8% of phenotypic variation for these traits. Several QTL for agronomic traits were also mapped in this study, including one and two QTL to the chromosomes 2A and 5AL, respectively, all for plant height, and two QTL to chromosome 6A for plant height and flowering date, respectively. The 5AL QTL for FHB resistance mapped in the marker interval of cfd39-cfa2185 in the present study is a novel QTL that originated from T. timopheevii and is reported here for the first time. Further validation of this QTL is required for wheat breeding programs to enhance resistance levels to FHB.

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Zhu, Shuquan, Kurt J. Leonard et Heidi F. Kaeppler. « Quantitative Trait Loci Associated with Seedling Resistance to Isolates of Puccinia coronata in Oat ». Phytopathology® 93, n^o 7 (juillet 2003) : 860–66. http://dx.doi.org/10.1094/phyto.2003.93.7.860.

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In our previous report, quantitative trait loci (QTL) for field adult plant resistance to crown rust were identified in an oat population of 152 F5:6 recombinant inbred lines from the cross of ‘Ogle’ (susceptible)/MAM17-5 (resistant). The objectives of the present study were to identify in the same population, the number, genomic location, and effect of QTL and digenic QTL epistasis associated with greenhouse seedling resistance to isolates of Puccinia coronata to determine if the QTL detected are isolate-specific and to compare them with previously detected QTL for field resistance. Reaction type was scored on greenhouse seedlings inoculated with three isolates. Composite interval mapping was conducted to identify genomic regions associated with resistance using a framework map of 272 molecular markers. Two QTL, Pcq1 and Pcq2, were identified for resistance to each of the three isolates. Pcq1, the major QTL controlling field resistance, did not confer detectable greenhouse seedling resistance when present singly; however, Pcq1 did serve as an enhancer of seedling resistance when it was combined with Pcq2. The final model explained 76.5, 77.9, and 79.3% of total phenotypic variation for resistance to isolates MNB248, MNB249, and MNB251, respectively. Race-specificity of quantitative resistance remains to be further examined.

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Bernal, Eduardo, Debora Liabeuf et David M. Francis. « Evaluating Quantitative Trait Locus Resistance in Tomato to Multiple Xanthomonas spp. » Plant Disease 104, n^o 2 (février 2020) : 423–29. http://dx.doi.org/10.1094/pdis-03-19-0669-re.

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Bacterial spot of tomato is a foliar disease caused by four Xanthomonas species. Identifying genetic resistance in wild tomatoes and subsequent breeding of varieties has been a strategy to reduce the loss from this disease because control using pesticides has been ineffective. Three independent sources of resistance have been identified with quantitative trait loci (QTL) mapping to the centromeric region on chromosome 11. These sources are derived from Hawaii 7998 (QTL-11A), PI 114490 (QTL-11B), and LA2533 (QTL-11C). To determine which QTL introgression from chromosome 11 provides the greatest resistance to multiple species, we developed near-isogenic lines (NILs) using marker-assisted backcrossing. In parallel, we developed an NIL that contains Rx-4/Xv3, which provides major gene resistance to Xanthomonas perforans. Additionally, we combined Rx-4/Xv3 resistance with QTL-11A. These sources of resistance were independently introduced into the susceptible parent, OH88119. During a 3-year period from 2016 to 2018, we evaluated backcross-derived families and NILs from each source in independent field trials inoculated with X. perforans, X. euvesicatoria, or X. gardneri. Our results suggest that both QTL-11C and QTL-11A combined with Rx-4/Xv3 provide effective genetic resistance against multiple Xanthomonas species. In addition, we provide evidence for additive to dominant genetic action for the QTL introgressions.

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Srinivasachary, N. Gosman, A. Steed, S. Faure, R. Bayles, P. Jennings et P. Nicholson. « Mapping of QTL associated with Fusarium head blight in spring wheat RL4137 ». Czech Journal of Genetics and Plant Breeding 44, No. 4 (22 janvier 2009) : 147–59. http://dx.doi.org/10.17221/70/2008-cjgpb.

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Fusarium head blight (FHB) is a destructive disease of wheat worldwide. We aimed to map QTL for FHB resistance in RL4137, a FHB resistant line derived from Frontana using 90 recombinant inbred lines (RIL) from a cross between RL4137 and the moderately FHB resistant variety Timgalen. A total of seven putative FHB resistance QTL (1B, 2B, 3A, 6A, 6B, 7A and 7D) were identified and in all but one instance, the alleles from RL4137 had a positive effect on FHB resistance. The QTL, Qfhs.jic-2band Qfhs.jic-6b contributed by the alleles from RL4137 and Timgalen, respectively were detected in multiple trials. Our study also identified three QTL for plant height (2B, 4A and 5B), two QTL for weight of infected spikelets from infected ears (2B and 6A) and one QTL for “awns” (2B). The QTL mapped on 2B for PH, WIS and awns co-localized with Qfhs.jic-2b. The FHB QTL on 1B and 6B were not associated with PH QTL and that the minor PH QTL on 4A and 5B, did not co-localise with any other FHB resistance QTL.

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Steffenson, B. J., et K. P. Smith. « Breeding Barley for Multiple Disease Resistance in the Upper MidwestRegion of the USA ». Czech Journal of Genetics and Plant Breeding 42, No. 3 (21 novembre 2011) : 79–86. http://dx.doi.org/10.17221/3646-cjgpb.

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The Upper Midwest is one of the largest barley production areas in the USA. In this region, diseases can markedly reduce both the yield and quality of the crop. Molecular and classical breeding techniques are being employed to develop cultivars with resistance to five different diseases in the Minnesota barley improvement program. Stem rust and spot blotch have been successfully controlled for many years through the deployment of the major gene Rpg1 and a major effect QTL, respectively. A sequence characterized amplified region (SCAR) marker developed from the sequence of Rpg1 has made marker-assisted selection (MAS) for stem rust resistance highly effective. The major QTL controlling durable adult plant spot blotch resistance was first identified in the Steptoe/Morex population. This QTL was completely suppressed in the Harrington/Morex and Dicktoo/Morex populations, highlighting the importance of genetic background for the expression of resistance. The onset of Fusarium head blight (FHB) in 1993 led to dramatic changes in the focus of the breeding program. Significant resources have been expended to develop populations for mapping resistance QTL and identify closely linked markers for MAS. This is a difficult challenge because FHB resistance is controlled by many QTL with small effects. Sources of resistance to net blotch and Septoria speckled leaf blotch (SSLB) have been identified in a number of barley accessions. These resistances are simply inherited and are being introgressed into elite lines via phenotypic and MAS. Continued progress toward multiple disease resistance will require efficient phenotypic screening, MAS, and utilization of discoveries in barley genomics to manage numerous resistance genes and desirable gene complexes assembled over decades of breeding.  

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Miklas, Phillip N., Richard Delorme et Ron Riley. « Identification of QTL Conditioning Resistance to White Mold in Snap Bean ». Journal of the American Society for Horticultural Science 128, n^o 4 (juillet 2003) : 564–70. http://dx.doi.org/10.21273/jashs.128.4.0564.

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Host resistance is an important component of integrated disease management strategies for control of Sclerotinia white mold disease in snap bean (Phaseolus vulgaris L.). Few resistant snap bean cultivars have been bred, however, because genetic resistance to white mold is not well understood. This study was conducted to examine inheritance and identify quantitative trait loci (QTL) for white mold resistance in an F5:7 recombinant inbred line (RIL) population (`Benton'/NY6020-4). `Benton' snap bean is susceptible to white mold. Snap bean germplasm line NY6020-4 has partial resistance. The parents and 77 F5:7 RILs were tested for resistance to white mold across four greenhouse and two field environments. Moderately high heritability estimates were observed for straw test (0.73) and field (0.62) reaction. Selective mapping of 27 random amplified polymorphic DNA (RAPD) markers detected two QTL conditioning resistance to white mold on linkage groups B6 and B8 of the core map. The B6 QTL explained 12% and B8 QTL 38% of the variation for disease reaction in the straw test. The two QTL explained 13% and 26% disease reaction in the field, respectively. Favorable alleles for all the QTL were derived from NY6020-4, except for the B6 QTL conditioning resistance to white mold in the field, which was derived from `Benton'. The B6 QTL was located near the Ur-4 rust resistance gene, and was associated with canopy height and lodging traits that condition disease avoidance. The B8 QTL was associated with increased internode length, an undesirable trait in snap bean, which may hamper use of white mold resistance derived from NY6020-4.

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Liu, C., J. Ma, H. B. Li, Y. X. Liu, G. R. Liu, S. M. Wen, M. X. Zhou, G. J. Yan et S. Chakraborty. « The homoeologous regions on long arms of group 3 chromosomes in wheat and barley harbour major crown rot resistance loci ». Czech Journal of Genetics and Plant Breeding 47, Special Issue (20 octobre 2011) : S109—S114. http://dx.doi.org/10.17221/3264-cjgpb.

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Crown rot (CR), caused by various Fusarium species, has become an important cereal disease worldwide and growing resistant varieties is an essential strategy to reduce the $A80 mil annual loss from CR in Australia. To facilitate the breeding of resistant varieties, we have screened 2514 wheat and 1059 barley genotypes and identified several lines with high levels of CR resistance in each crop. Initially focused on two wheat and one barley resistance sources, we have identified major QTL with unprecedented magnitudes. Two wheat QTL explain between 35% (LOD 7.6) and 49% (LOD 10.8) and the barley QTL explains up to 63% (LOD 14.8) of the phenotypic variance. One of the wheat QTL has been further assessed in four validation populations, and the presence of this QTL alone reduces CR severity by 33% on average. Surprisingly, all of the three major CR QTL are located in similar regions on the long arms of the homoeologous group 3 chromosomes, the two wheat QTL on 3BL and the barley QTL on 3HL. The possible homoeologous relationship between the 3BL wheat QTL and the 3HL barley QTL warrants further investigation. Relative rearrangements between 3H and 3B chromosomes are unknown, although the relative distances between the different QTL and the centromeres seem to be different. Compared with the barley QTL, the 3BL wheat QTL seems to be more distally located. However genetic distance can be affected by many factors including the use of different populations, thus the differences in genetic distances between the two different genera may have only limited value. The physical map of wheat chromosome 3B, which was recently made available as the first such resources for wheat, would make such a study much easier. Results will be presented on the detection, genetic analysis and mapping of these new sources of CR resistance.

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Zhou, Hao, et Brian J. Steffenson. « Association Mapping of Septoria Speckled Leaf Blotch Resistance in U.S. Barley Breeding Germplasm ». Phytopathology® 103, n^o 6 (juin 2013) : 600–609. http://dx.doi.org/10.1094/phyto-10-12-0271-r.

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Septoria speckled leaf blotch (SSLB) is a sporadic but important disease of barley (Hordeum vulgare) in the Upper Midwest region of the United States and Prairie Provinces of Canada that is caused primarily by Septoria passerinii. Most of the widely grown cultivars in the region are susceptible to the disease. To identify and map SSLB resistance loci in U.S. barley breeding germplasm, we employed an association mapping approach using 3,840 breeding lines and cultivars and nearly 3,000 single-nucleotide polymorphism markers previously mapped to the seven barley chromosomes. SSLB infection responses (IRs) were assayed on seedling plants in the greenhouse using a 0-to-5 scale. From the analysis of four yearly panels consisting of 960 lines each, four quantitative trait loci (QTL) for SSLB resistance were identified: one on chromosome 1H (Rsp-qtl-H_12_31144), one on chromosome 3H (Rsp-qtl-3H_12_31488), and two on chromosome 6H (Rsp-qtl-6H_11_21032 and Rsp-qtl-6H_11_10064). Individual resistance QTL reduced the mean IR from 9 to 38% compared with lines lacking any resistance alleles. However, the combination of all four resistance QTL together reduced the mean IR by 83%. The markers found associated with these QTL will be valuable for programs utilizing marker-assisted selection for SSLB resistance.

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Thauvin, Jean-Noël, Joanne Russell, Dominique Vequaud, Mark Looseley, Micha Bayer, Pierre-Marie Le Roux, Pierre Pin, Robbie Waugh et Anna Avrova. « Genome-Wide Association Study for Resistance to Rhynchosporium in a Diverse Collection of Spring Barley Germplasm ». Agronomy 12, n^o 4 (24 mars 2022) : 782. http://dx.doi.org/10.3390/agronomy12040782.

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Rhynchosporium is one of the main biotic stresses on barley production worldwide. A set of 312 spring barley accessions was tested in four different locations over 3 years, to identify novel genetic resistances to rhynchosporium and to explore the allelic diversity for resistance genes present in this global germplasm collection. High-density genotypes from exome capture and RNA-seq were used to conduct high-resolution association mapping. Seven quantitative trait loci (QTL) were detected, including one in the Rrs2 region, amongst five containing known resistances. Relatively short physical intervals harbouring these resistances were proposed, providing a platform for the identification of underlying genes and tightly linked genetic markers for use in marker assisted selection. Genes encoding kinases were present in four of the QTL, in addition to Rrs1 and Rrs18, two loci known to contribute to rhynchosporium resistance. The frequencies and distributions of these novel and known QTL were superimposed on the regional origin of the landrace genotypes comprising the genome-wide association studies (GWAS) panel, highlighting the value of genetic resources as a source of diverse genetically controlled resistance to rhynchosporium. The detected QTL along with their linked genetic markers, could be exploited either directly for breeding purposes or for candidate gene identification in future studies.

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Würschum, Tobias, Willmar L. Leiser, Simon M. Langer, Matthew R. Tucker et Thomas Miedaner. « Genetic Architecture of Cereal Leaf Beetle Resistance in Wheat ». Plants 9, n^o 9 (28 août 2020) : 1117. http://dx.doi.org/10.3390/plants9091117.

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Wheat production can be severely damaged by endemic and invasive insect pests. Here, we investigated resistance to cereal leaf beetle in a panel of 876 winter wheat cultivars, and dissected the genetic architecture underlying this insect resistance by association mapping. We observed an effect of heading date on cereal leaf beetle infestation, with earlier heading cultivars being more heavily infested. Flag leaf glaucousness was also found to be correlated with resistance. In line with the strong effect of heading time, we identified Ppd-D1 as a major quantitative trait locus (QTL), explaining 35% of the genotypic variance of cereal leaf beetle resistance. The other identified putative QTL explained much less of the genotypic variance, suggesting a genetic architecture with many small-effect QTL, which was corroborated by a genomic prediction approach. Collectively, our results add to our understanding of the genetic control underlying insect resistances in small-grain cereals.

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Calenge, F., A. Faure, M. Goerre, C. Gebhardt, W. E. Van de Weg, L. Parisi et C. E. Durel. « Quantitative Trait Loci (QTL) Analysis Reveals Both Broad-Spectrum and Isolate-Specific QTL for Scab Resistance in an Apple Progeny Challenged with Eight Isolates of Venturia inaequalis ». Phytopathology® 94, n^o 4 (avril 2004) : 370–79. http://dx.doi.org/10.1094/phyto.2004.94.4.370.

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The major scab resistance gene Vf, extensively used in apple breeding programs, was recently overcome by the new races 6 and 7 of the fungal pathogen Venturia inaequalis. New, more durable, scab resistance genes are needed in apple breeding programs. F1 progeny derived from the cross between partially resistant apple cv. Discovery and apple hybrid ‘TN10-8’ were inoculated in the greenhouse with eight isolates of V. inaequalis, including isolates able to overcome Vf. One major resistance gene, Vg, and seven quantitative trait loci (QTL) were identified for resistance to these isolates. Three QTL on linkage group (LG)12, LG13, and LG15 were clearly isolate-specific. Another QTL on LG5 was detected with two isolates. Three QTL on LG1, LG2, and LG17 were identified with most isolates tested, but not with every isolate. The QTL on LG2 displayed alleles conferring different specificities. This QTL co-localized with the major scab resistance genes Vr and Vh8, whereas the QTL on LG1 colocalized with Vf. These results contribute to a better understanding of the genetic basis of the V. inaequalis-Malus × domestica interaction.

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Shao, Yujiao, Yusen Shen, Feifei He et Zaiyun Li. « QTL Identification for Stem Fiber, Strength and Rot Resistance in a DH Population from an Alien Introgression of Brassica napus ». Plants 11, n^o 3 (29 janvier 2022) : 373. http://dx.doi.org/10.3390/plants11030373.

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Stem fiber, stem strength and stem-rot resistance are important agronomic traits in Brassica napus. To understand the molecular mechanism that controls the stem-related traits, we investigated the stem lignin (ADL), cellulose (Cel), hemicellulose (Hem) content, S/G monolignol ratio (SG), stem breaking force (BF), breaking strength (F) and Sclerotinia sclerotiorum resistance (SSR). Each trait was significantly positively or negatively correlated with more than three of the other six traits. QTL mapping for ADL, Cel, Hem, SG, BF, F and SSR were performed using a doubled haploid population derived from an intertribal B. napus introgression line ‘Y689′ crossed with B. napus cv. ‘Westar’. A total of 67 additive QTL were identified and integrated into 55 consensus QTL by meta-analysis. Among the 55 consensus QTL, 23 (41.8%) QTL were co-located and were integrated into 11 unique QTL. The QTL by environment (Q × E) interactions were analyzed and 22 combined QTL were identified. In addition, candidate genes within the QTL intervals were proposed based on the known function of Arabidopsis orthologs. These results provided valuable information for improving lodging resistance, S. sclerotiorum resistance and mechanized harvesting of B. napus.

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Zhou, Wenchun, Frederic L. Kolb, Jianbin Yu, Guihua Bai, Larry K. Boze et Leslie L. Domier. « Molecular characterization of Fusarium head blight resistance in Wangshuibai with simple sequence repeat and amplified fragment length polymorphism markers ». Genome 47, n^o 6 (1 décembre 2004) : 1137–43. http://dx.doi.org/10.1139/g04-069.

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Molecular mapping of Fusarium head blight (FHB) resistance quantitative trait loci (QTL) and marker-assisted selection of these QTL will aid in the development of resistant cultivars. Most reported FHB resistance QTL are from 'Sumai 3' and its derivatives. 'Wangshuibai' is a FHB-resistant landrace that originated from China and is not known to be related to 'Sumai 3'. A mapping population of 139 F5:6 recombinant inbred lines was developed from a cross of 'Wangshuibai' and 'Wheaton'. This population was developed to map the FHB-resistant QTL in 'Wangshuibai' and was evaluated twice for Type II FHB resistance. A total of 1196 simple sequence repeat and amplified fragment length polymorphism markers were screened on this population, and four FHB resistance QTL were detected. A major QTL near the end of 3BS explained 37.3% of the phenotypic variation. Another QTL on 3BS, located close to the centromere, explained 7.4% of the phenotypic variation. Two additional QTL on 7AL and 1BL explained 9.8% and 11.9% of the phenotypic variation, respectively. The simple sequence repeat and amplified fragment length polymorphism markers closely linked to these QTL may be useful for stacking QTL from 'Wangshuibai' and other sources to develop cultivars with transgressive FHB resistance.Key words: head scab, marker-assisted selection, molecular mapping, Triticum aestivum L., wheat.

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Cheng, Bin, Xu Gao, Ning Cao, Yanqing Ding, Tianqing Chen, Qiang Zhou, Yu Gao, Zhihai Xin et Liyi Zhang. « QTL mapping for adult plant resistance to wheat stripe rust in M96-5 × Guixie 3 wheat population ». Journal of Applied Genetics 63, n^o 2 (26 mars 2022) : 265–79. http://dx.doi.org/10.1007/s13353-022-00686-z.

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AbstractDevelopment of cultivars with multiple resistances has proven to be an effective way to prevent diseases in wheat breeding. The Guixie 3 variety (GX3) has shown excellent performance in resistance to stripe rust in field for many years. The purpose of this study was to detect quantitative trait loci (QTL) associated with resistance to stripe rust in the adult plant stage and determine closely linked molecular markers. A population of recombinant inbred lines (n = 228) was derived from a cross between the susceptible landrace Mian 96–5 (M96-5) and GX3 variety and evaluated in multiple field studies, and QTL analysis enabled to elucidate genetic architecture of wheat resistance to stripe rust. A total of 19 QTL for stripe rust resistance were mapped on 12 chromosomes using phenotypic data from multiple field tests over the course of 6 years. These chromosomes included 1B (2), 1D (2), 2A (2), 2B (2), 2D (1), 4B (2), 4D (1), 5A (3), 5B (1), 6A (1), 6B (1), and 7B (1). Two stable QTL on chromosomes 2AS (Qyr.gaas.2A) and 6AL (Qyr.gaas.6A) were detected in six and five different environments, respectively; in both QTL, positive allele was contributed by GX3 variety. Qyr.gaas.2A was found to be crucial for increasing adult plant resistance, which may explain the large phenotypic variation of 45.52%. Our results provide theoretical and molecular insight for wheat breeding and suggest the cloning of genes associated with the GX3 variety may be beneficial in future studies.

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Liu, Yan, Xinshuai Qi, Dave R. Gealy, Kenneth M. Olsen, Ana L. Caicedo et Yulin Jia. « QTL Analysis for Resistance to Blast Disease in U.S. Weedy Rice ». Molecular Plant-Microbe Interactions® 28, n^o 7 (juillet 2015) : 834–44. http://dx.doi.org/10.1094/mpmi-12-14-0386-r.

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Understanding the genetic architecture of adaptation is of great importance in evolutionary biology. U.S. weedy rice is well adapted to the local conditions in U.S. rice fields. Rice blast disease is one of the most destructive diseases of cultivated rice worldwide. However, information about resistance to blast in weedy rice is limited. Here, we evaluated the disease reactions of 60 U.S. weedy rice accessions with 14 blast races, and investigated the quantitative trait loci (QTL) associated with blast resistance in two major ecotypes of U.S. weedy rice. Our results revealed that U.S. weedy rice exhibited a broad resistance spectrum. Using genotyping by sequencing, we identified 28 resistance QTL in two U.S. weedy rice ecotypes. The resistance QTL with relatively large and small effects suggest that U.S. weedy rice groups have adapted to blast disease using two methods, both major resistance (R) genes and QTL. Three genomic loci shared by some of the resistance QTL indicated that these loci may contribute to no-race-specific resistance in weedy rice. Comparing with known blast disease R genes, we found that the R genes at these resistance QTL are novel, suggesting that U.S. weedy rice is a potential source of novel blast R genes for resistant breeding.

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Ruan, Yuefeng, André Comeau, François Langevin, Pierre Hucl, John M. Clarke, Anita Brule-Babel et Curtis J. Pozniak. « Identification of novel QTL for resistance to Fusarium head blight in a tetraploid wheat population ». Genome 55, n^o 12 (décembre 2012) : 853–64. http://dx.doi.org/10.1139/gen-2012-0110.

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Most tetraploid durum wheat (Triticum turgidum L var. durum) cultivars are susceptible to Fusarium head blight (FHB). This study reports novel quantitative trait loci (QTL) associated with FHB resistance. A backcross recombinant inbred line (BCRIL) population was developed from the cross BGRC3487/2*DT735, and 160 lines were evaluated for resistance to Fusarium graminearum Schwabe (teleomorph Gibberella zeae (Schwein. Petch) in field trials over 3 years (2008–2010) and to a F. graminearum 3-acetyl-deoxynivalenol (3-ADON) chemotype in greenhouse trials. The population was genotyped with 948 polymorphic loci using DArT and microsatellite markers. Eleven QTL were associated with FHB resistance under field conditions on chromosomes 2A, 3B, 5A, 5B, 7A, and 7B. Two of these, QFhb.usw-3B from BGRC3487 and QFhb.usw-7A2, were consistently detected over environments. The QFhb.usw-3B QTL was in a similar position to a resistance QTL in hexaploid wheat. The combination of the two QTL reduced field index by 53.5%–86.2%. Two QTL for resistance to the 3-ADON chemotype were detected on chromosomes 1B and 4B. Both BGRC3487 and DT735 could provide new sources of FHB resistance and the combination of QTL reported here could be valuable tools in breeding FHB-resistant durum wheat.

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Ramalingam, J., C. M. Vera Cruz, K. Kukreja, J. M. Chittoor, J. L. Wu, S. W. Lee, M. Baraoidan et al. « Candidate Defense Genes from Rice, Barley, and Maize and Their Association with Qualitative and Quantitative Resistance in Rice ». Molecular Plant-Microbe Interactions® 16, n^o 1 (janvier 2003) : 14–24. http://dx.doi.org/10.1094/mpmi.2003.16.1.14.

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Candidate genes involved in both recognition (resistance gene analogs [RGAs]) and general plant defense (putative defense response [DR]) were used as molecular markers to test for association with resistance in rice to blast, bacterial blight (BB), sheath blight, and brown plant-hopper (BPH). The 118 marker loci were either polymerase chain reaction-based RGA markers or restriction fragment length polymorphism (RFLP) markers that included RGAs or putative DR genes from rice, barley, and maize. The markers were placed on an existing RFLP map generated from a mapping population of 116 doubled haploid (DH) lines derived from a cross between an improved indica rice cultivar, IR64, and a traditional japonica cultivar, Azucena. Most of the RGAs and DR genes detected a single locus with variable copy number and mapped on different chromosomes. Clusters of RGAs were observed, most notably on chromosome 11 where many known blast and BB resistance genes and quantitative trait loci (QTL) for blast, BB, sheath blight, and BPH were located. Major resistance genes and QTL for blast and BB resistance located on different chromosomes were associated with several candidate genes. Six putative QTL for BB were located on chromosomes 2, 3, 5, 7, and 8 and nine QTL for BPH resistance were located to chromosomes 3, 4, 6, 11, and 12. The alleles of QTL for BPH resistance were mostly from IR64 and each explained between 11.3 and 20.6% of the phenotypic variance. The alleles for BB resistance were only from the Azucena parent and each explained at least 8.4% of the variation. Several candidate RGA and DR gene markers were associated with QTL from the pathogens and pest. Several RGAs were mapped to BB QTL. Dihydrofolate reductase thymidylate synthase co-localized with two BPH QTL associated with plant response to feeding and also to blast QTL. Blast QTL also were associated with aldose reductase, oxalate oxidase, JAMyb (a jasmonic acid-induced Myb transcription factor), and peroxidase markers. The frame map provides reference points to select candidate genes for cosegregation analysis using other mapping populations, isogenic lines, and mutants.

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Marczewski, Waldemar, Bogdan Flis, Jerzy Syller, Ralf Schäfer-Pregl et Christiane Gebhardt. « A Major Quantitative Trait Locus for Resistance to Potato leafroll virus Is Located in a Resistance Hotspot on Potato Chromosome XI and Is Tightly Linked to N-Gene-Like Markers ». Molecular Plant-Microbe Interactions® 14, n^o 12 (décembre 2001) : 1420–25. http://dx.doi.org/10.1094/mpmi.2001.14.12.1420.

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Potato leafroll virus (PLRV) causes one of the most widespread and important virus diseases in potato. Resistance to PLRV is controlled by genetic factors that limit plant infection by viruliferous aphids or virus multiplication and accumulation. Quantitative trait locus (QTL) analysis of resistance to virus accumulation revealed one major and two minor QTL. The major QTL, PLRV.1, mapped to potato chromosome XI in a resistance hotspot containing several genes for qualitative and quantitative resistance to viruses and other potato pathogens. This QTL explained between 50 and 60% of the phenotypic variance. The two minor QTL mapped to chromosomes V and VI. Genes with sequence similarity to the tobacco N gene for resistance to Tobacco mosaic virus were tightly linked to PLRV.1. The cDNA sequence of an N-like gene was used to develop the sequence characterized amplified region (SCAR) marker N1271164 that can assist in the selection of potatoes with resistance to PLRV.

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Yu, G. T., J. D. Franckowiak, S. M. Neate, B. Zhang et R. D. Horsley. « A native QTL for Fusarium head blight resistance in North American barley (Hordeum vulgareL.) independent of height, maturity, and spike type loci ». Genome 53, n^o 2 (février 2010) : 111–18. http://dx.doi.org/10.1139/g09-091.

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Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe (teleomorph Gibberella zeae (Schwein.) Petch), is one of the major diseases of barley (Hordeum vulgare L.) in eastern China, the Upper Midwest of the USA, and the eastern Prairie Provinces of Canada. To identify quantitative trait loci (QTL) controlling FHB resistance, a recombinant inbred line population (F6:7) was developed from the cross Zhenongda 7/PI 643302. The population was phenotyped for resistance to FHB in two experiments in China and four experiments in North Dakota. Accumulation of the mycotoxin deoxynivalenol was determined in one experiment in China and two in North Dakota. Simplified composite interval mapping was performed on the whole genome level using the software MQTL. The QTL FHB-2 from PI 643302 for FHB resistance was found on the distal portion of chromosome 2HL in all six FHB screening environments. This QTL accounted for 14% of phenotypic variation over six environments and was not associated with heading date or plant height. The FHB resistance QTL FHB-2 detected near the end of chromosome 2HL is in a different location from those found previously and is therefore probably unique. Because the QTL was not contributed by the Chinese cultivar Zhenongda 7, it is likely a native QTL present in North American barley. The QTL FHB-2 represents the first reported QTL for native FHB resistance in North American germ plasm and has been given the provisional name Qrgz-2H-14. This QTL should be considered for pyramiding with other FHB QTL previously mapped.

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Simeone, Rosanna, Luciana Piarulli, Domenica Nigro, Massimo Antonio Signorile, Emanuela Blanco, Giacomo Mangini et Antonio Blanco. « Mapping Powdery Mildew (Blumeria graminis f. sp. tritici) Resistance in Wild and Cultivated Tetraploid Wheats ». International Journal of Molecular Sciences 21, n^o 21 (24 octobre 2020) : 7910. http://dx.doi.org/10.3390/ijms21217910.

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Wheat is the most widely grown crop and represents the staple food for one third of the world’s population. Wheat is attacked by a large variety of pathogens and the use of resistant cultivars is an effective and environmentally safe strategy for controlling diseases and eliminating the use of fungicides. In this study, a collection of wild and cultivated tetraploid wheats (Triticum turgidum) were evaluated for seedling resistance (SR) and adult plant resistance (APR) to powdery mildew (Blumeria graminis) and genotyped with a 90K single nucleotide polymorphism (SNP) array to identify new sources of resistance genes. The genome-wide association mapping detected 18 quantitative trait loci (QTL) for APR and 8 QTL for SR, four of which were identical or at least closely linked to four QTL for APR. Thirteen candidate genes, containing nucleotide binding sites and leucine-rich repeats, were localized in the confidence intervals of the QTL-tagging SNPs. The marker IWB6155, associated to QPm.mgb-1AS, was located within the gene TRITD1Av1G004560 coding for a disease resistance protein. While most of the identified QTL were described previously, five QTL for APR (QPm.mgb-1AS, QPm.mgb-2BS, QPm.mgb-3BL.1, QPm.mgb-4BL, QPm.mgb-7BS.1) and three QTL for SR (QPm.mgb-3BL.3, QPm.mgb-5AL.2, QPm.mgb-7BS.2) were mapped on chromosome regions where no resistance gene was reported before. The novel QTL/genes can contribute to enriching the resistance sources available to breeders.

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Saleem, Kamran, Mogens Støvring Hovmøller, Rodrigo Labouriau, Annemarie Fejer Justesen, Jihad Orabi, Jeppe Reitan Andersen et Chris Khadgi Sørensen. « Macroscopic and Microscopic Phenotyping Using Diverse Yellow Rust Races Increased the Resolution of Seedling and Adult Plant Resistance in Wheat Breeding Lines ». Agronomy 12, n^o 5 (28 avril 2022) : 1062. http://dx.doi.org/10.3390/agronomy12051062.

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We characterized yellow rust (YR) resistance in sixteen winter wheat breeding lines using three different pathogen races and macroscopic and microscopic phenotyping in lab and greenhouse. Three rust races were used on seedlings and two races on fifth and flag leaf growth stages. The wheat lines were previously characterized to possess none or different quantitative trait loci for YR resistance in field trials. At the seedling stage, twelve lines showed race-specific seedling resistance whereas four lines gave strong seedling resistance to all three races. Seven of eight lines with QTL.1B showed strong seedling resistance against the two races also used at fifth and flag leaves. Microscopic phenotyping of line NOS50906215 (QTL.1B) showed small fungal colonies stopped within 3 dpi associated with extensive hypersensitive response (HR). The lines NOS51014910 and NOS51014911 (QTL.3D alone) showed strong adult plant resistance (APR) from the fifth leaf stage. The lines NOS70140801 and NOS70140808 (QTL.3D + 7B) showed strong APR to one race but partial resistance to the other race at all growth stages. Microscopic phenotyping of line NOS70140801 (QTL.3D + 7B) showed more fungal growth and less HR against the race revealing strong APR compared to the one revealing partial resistance. Line NOS51010312 (QTL.7B alone) showed strong APR response against both races whereas line NOS51010313 (QTL.7B) was susceptible. A partial APR response was observed on line NOS51005019 (no QTLs reported). In conclusion, the approach of combining macroscopic and microscopic phenotyping and diverse pathogen races facilitates the identification of multiple and diverse seedling and adult plant resistance responses to yellow rust in wheat.

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Acevedo, M., E. W. Jackson, J. Chong, H. W. Rines, S. Harrison et J. M. Bonman. « Identification and Validation of Quantitative Trait Loci for Partial Resistance to Crown Rust in Oat ». Phytopathology® 100, n^o 5 (mai 2010) : 511–21. http://dx.doi.org/10.1094/phyto-100-5-0511.

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Management of oat crown rust disease with host resistance is challenging because major gene resistance is generally short lived. Partially resistant oat cultivars could benefit oat growers by providing more durable resistance. The objective of this study was to validate and discover quantitative trait loci (QTL) affecting crown rust resistance in the partially resistant oat line MN841801-1 using conventional and molecular assessments of disease produced in single-race greenhouse inoculations, single-race polycyclic field tests, and under natural infection in disease-conducive environments. Crown rust was assessed on 150 F6:9 MN841801-1/‘Noble-2’ recombinant inbred lines. In total, eight QTL associated with MN841801-1 alleles were detected. Of these, seven matched QTL previously identified while a new QTL (Prq8) was detected on linkage group MN13. Four QTL (Prq1a, Prq2, Prq7, and Prq8) were consistently detected and predicative genetic assays for these QTL should be developed for future validation in additional genetic backgrounds.

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Chrpová, J., V. Šíp, T. Sedláček, L. Štočková, O. Veškrna et P. Horčička. « Effectiveness of marker-based selection for Fusarium head blight resistance in spring wheat ». Czech Journal of Genetics and Plant Breeding 47, Special Issue (20 octobre 2011) : S123—S129. http://dx.doi.org/10.17221/3266-cjgpb.

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The effect of selection for two donor-QTL from Fusarium head blight (FHB) resistant spring wheat variety Sumai 3 on the reduction of deoxynivalenol (DON) content and FHB index was evaluated in field trials over two years (2008, 2009) following artificial inoculation with Fusarium culmorum. This study was conducted on populations of recombinant inbred lines derived from two crosses, Sumai 3/Swedget and Sumai 3/SG-S 191-01. DON content and FHB index were significantly reduced in both crosses in the genotype classes with two stacked donor QTL on chromosomes 3B and 5A in comparison to genotype classes with no donor QTL. In the cross Sumai 3/Swedget the selection for QTL alleles from 3B and 5A resulted in a 63.4% reduction in DON content, and a 51.8% reduction in the FHB index. Similarly, there was a 35.9% and 31.9% reduction, respectively, in the cross Sumai 3/SG-S 191-01. The single effect of the donor-QTL allele from 3B was significant only in the cross Sumai 3/Swedjet. The presence or absence of awns affected both DON content and FHB index in both populations, but was only significantly in the cross Sumai 3/SG-S 191-01. In this cross the effect of selection for fully awned genotypes was particularly evident on a reduction of both DON and FHB index in classes with neither donor QTL, or the 3B QTL. However, the data indicate that the “awnedness” effect on FHB resistance may be highly variable and is probably greater on reducing FHB symptoms than on DON content. The results confirmed that marker-based introgression of resistance QTLs on chromosomes 3B and 5A in traditional breeding materials can enrich populations for resistance types, but it was also shown that the effect of marker-based selection need not be large in all crosses and a similar effect can probably be reached by indirect selection for some FHB-related traits.

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Bormann, Christina Angelika, Andreas Marcus Rickert, Rosa Angela Castillo Ruiz, Jürgen Paal, Jens Lübeck, Josef Strahwald, Karsten Buhr et Christiane Gebhardt. « Tagging Quantitative Trait Loci for Maturity-Corrected Late Blight Resistance in Tetraploid Potato with PCR-Based Candidate Gene Markers ». Molecular Plant-Microbe Interactions® 17, n^o 10 (octobre 2004) : 1126–38. http://dx.doi.org/10.1094/mpmi.2004.17.10.1126.

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Late blight caused by the oomycete Phytophthora infestans is the economically most important and destructive disease in potato cultivation. Quantitative resistance to late blight available in tetraploid cultivars is correlated with late maturity in temperate climates, which is an undesirable characteristic. A total of 30 DNA-based markers known to be linked to loci for pathogen resistance in diploid potato were selected and tested as polymerase chain reaction-based markers for linkage with quantitative trait loci (QTL) for late blight resistance and plant maturity in two half-sib families of tetraploid potatoes. Most markers originated from within or were physically closely linked to candidate genes for quantitative resistance factors. The families were repeatedly evaluated in the field for quantitative resistance to late blight and maturity. Resistance was corrected for the maturity effect. Nine of eleven different map segments tagged by the markers harbored QTL affecting maturity-corrected resistance. Interactions were found between unlinked resistance QTL, providing testable strategies for marker-assisted selection in tetraploid potato. Based on the linkage observed between QTL for resistance and plant maturity and based on the genetic interactions observed between candidate genes tagging resistance QTL, we discuss models for the molecular basis of quantitative resistance and maturity.

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Kim, Nayoung, Won-Hee Kang, Jundae Lee et Seon-In Yeom. « Development of Clustered Resistance Gene Analogs-Based Markers of Resistance toPhytophthora capsiciin Chili Pepper ». BioMed Research International 2019 (3 janvier 2019) : 1–12. http://dx.doi.org/10.1155/2019/1093186.

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The soil-borne pathogenPhytophthora capsicicauses severe destruction ofCapsicumspp. Resistance inCapsicumagainstP. capsiciis controlled by numerous minor quantitative trait loci (QTLs) and a consistent major QTL on chromosome 5. Molecular markers onCapsicumchromosome 5 have been developed to identify the predominant genetic contributor to resistance but have achieved little success. In this study, previously reported molecular markers were used to reanalyze the major QTL region on chromosome 5 (6.2 Mbp to 139.2 Mbp). Candidate resistance gene analogs (RGAs) were identified in the extended major QTL region including 14 nucleotide binding site leucine-rich repeats, 3 receptor-like kinases, and 1 receptor-like protein. Sequence comparison of the candidate RGAs was performed between twoCapsicumgermplasms that are resistant and susceptible, respectively, toP. capsici.11 novel RGA-based markers were developed through high-resolution melting analysis which were closely linked to the major QTL forP. capsiciresistance. Among the markers, CaNB-5480 showed the highest cosegregation rate at 86.9% and can be applied to genotyping of the germplasms that were not amenable by previous markers. With combination of three markers such as CaNB-5480, CaRP-5130 and CaNB-5330 increased genotyping accuracy for 61Capsicumaccessions. These could be useful to facilitate high-throughput germplasm screening and further characterize resistance genes againstP. capsiciin pepper.

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Cervantes-Flores, Jim C., G. Craig Yencho, Kenneth V. Pecota, Bryon Sosinski et Robert O. M. Mwanga. « Detection of Quantitative Trait Loci and Inheritance of Root-knot Nematode Resistance in Sweetpotato ». Journal of the American Society for Horticultural Science 133, n^o 6 (novembre 2008) : 844–51. http://dx.doi.org/10.21273/jashs.133.6.844.

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Resistance to root-knot nematodes [Meloidogyne incognita (Kofoid & White) Chitwood] in sweetpotato [Ipomoea batatas (L.) Lam.] was studied in a mapping population consisting of 240 progeny derived from a cross between ‘Beauregard’, the predominant cultivar in the United States, and ‘Tanzania’, an African landrace. Quantitative trait loci (QTL) analyses to locate markers associated with resistance to root-knot nematodes (RKN) were performed using genetic maps based on parental segregation in ‘Beauregard’ and ‘Tanzania’ consisting of 726 and 947 single-dose amplified fragment length polymorphism (AFLP) markers, respectively. RKN resistance in the progeny was highly skewed with most of the progeny exhibiting medium to high levels of resistance. Single-point analysis of variance and interval mapping revealed seven consistently significant QTL in ‘Tanzania’ and two significant QTL in ‘Beauregard’. In ‘Tanzania’, three QTL were associated with reduction in resistance as measured by the number of RKN egg masses and explained ≈20% of the variation. Another four QTL had positive effects on resistance and explained ≈21% of the variation. Other minor QTL explained ≈2% or less of the variation but were not always consistent across geographical locations. In ‘Beauregard’, two QTL had positive effects on RKN resistance and explained ≈6% of the observed variation. Based on molecular and phenotypic data, RKN resistance in sweetpotato is hypothesized to be conferred by several genes, but at least nine AFLP markers (seven from ‘Tanzania’ and two from ‘Beauregard’) are associated with genomic regions that have the biggest effect in the number of egg masses of RKN produced in the root system.

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Perchepied, L., M. Bardin, C. Dogimont et M. Pitrat. « Relationship Between Loci Conferring Downy Mildew and Powdery Mildew Resistance in Melon Assessed by Quantitative Trait Loci Mapping ». Phytopathology® 95, n^o 5 (mai 2005) : 556–65. http://dx.doi.org/10.1094/phyto-95-0556.

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Partial resistance to downy mildew (Pseudoperonospora cubensis) and complete resistance to powdery mildew (Podosphaera xanthii races 1, 2, 3, and 5 and Golovinomyces cichoracearum race 1) were studied using a recombinant inbred line population between ‘PI 124112’ (resistant to both diseases) and ‘Védrantais’ (susceptible line). A genetic map of melon was constructed to tag these resistances with DNA markers. Natural and artificial inoculations of Pseudoperonospora cubensis were performed and replicated in several locations. One major quantitative trait loci (QTL), pcXII.1, was consistently detected among the locations and explained between 12 to 38% of the phenotypic variation for Pseudoperonospora cubensis resistance. Eight other Pseudoperonospora cubensis resistance QTL were identified. Artificial inoculations were performed with several strains of four races of Podosphaera xanthii and one race of G. cichoracearum. Two independent major genes, PmV.1 and PmXII.1, were identified and shown to be involved in the simple resistance to powdery mildew. Three digenic epistatic interactions involving four loci were detected for two races of Podosphaera xanthii and one race of G. cichoracearum. Co-localization between PmV.1, resistance genes, and resistance genes homologues was observed. Linkage between the major resistance QTL to Pseudoperonospora cubensis, pcXII.1, and one of the two resistance genes to powdery mildew, PmXII.1, was demonstrated.

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Sobrizal, Sobrizal, Masdiar Bustamam, Carkum Carkum, Ahmad Warsun, Soeranto Human et Yoshimichi Fukuta. « IDENTIFICATION OF A MAJOR QUANTITATIVE TRAIT LOCUS CONFERRING RICE BLAST RESISTANCE USING RECOMBINANT INBRED LINES ». Indonesian Journal of Agricultural Science 11, n^o 1 (16 mai 2013) : 1. http://dx.doi.org/10.21082/ijas.v11n1.2010.p1-10.

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Blast disease caused by Pyricularia oryzae is one of the limiting factors for rice production world wide. The use of resistant varieties for managing blast disease is considered as the most eco-friendly approaches. However, their resistances may be broken down within a few years due to the appearance of new virulent blast races in the field. The objective of the present study was to identify the quantitative trait locus (QTL) conferring resistance to blast disease using 126 recombinant inbred (RI) lines originated from a crossing of a durably resistant upland rice genotype (Laka) and a highly susceptible rice accession cultivar (Kencana Bali). The RI population was developed through a single seed descent method from 1997 to 2004. Resistance of the RI lines was evaluated for blast in an endemic area of Sukabumi, West Java, in 2005. Disease intensity of the blast was examined following the standard evaluation system developed by the International Rice Research Institute (IRRI). At the same year the RI lines were analyzed with 134 DNA markers. Results of the study showed that one major QTL was found to be associated with blast resistance, and this QTL was located near RM2136 marker on the long arm of chromosome 11. This QTL explained 87% of the phenotypic variation with 37% additive effect. The map position of this QTL differed from that of a partial resistant gene, Pi34, identified previously on chromosome 11 in the Japanese durably resistant variety, Chubu 32. The QTL, however, was almost at the same position as that of the multiple allele-resistant gene, Pik. Therefore, an allelic test should be conducted to clarify the allelic relationship between QTL identified in this study and the Pik. The RI lines are the permanent segregating population that could be very useful for analysing phenotypic variations of important agronomic traits possibly owned by the RI lines. The major QTL identified in this study could be used as a genetic resource in improvement of rice varieties for blast resistance in Indonesia

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Maree, Gerrie, Renée Prins, Lesley Boyd, Howard Castelyn, Cornelia Bender, Willem Boshoff et Zacharias Pretorius. « Assessing the Individual and Combined Effects of QTL for Adult Plant Stripe Rust Resistance Derived from Cappelle-Desprez ». Agronomy 9, n^o 3 (25 mars 2019) : 154. http://dx.doi.org/10.3390/agronomy9030154.

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The release of commercial wheat cultivars resistant to stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), remains one of the primary objectives in many breeding programs. Previous studies of adult plant resistance derived from the winter wheat cultivar Cappelle-Desprez identified the quantitative trait loci (QTL) QYr.ufs-2A, QYr.ufs-2D, QYr.ufs-5B and QYr.ufs-6D to affect stripe rust under South African conditions. Phenotypic field assessment, fluorescence microscopy and molecular analysis were used to characterise recombinant inbred lines differing in number and combinations of these QTL. Besides the confirmation of enhanced resistance through co-occurring resistance loci, varying levels of defence, conditioned by different QTL combinations were observed. Carriers of QYr.ufs-2A or QYr.ufs-2D, accompanied by at least one other QTL, exhibited higher resistance levels than lines with a single QTL. The knowledge gained in this study will help wheat breeders to develop cultivars with more diverse combinations and potentially more durable sources of stripe rust resistance.

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Pereira, Messias Gonzaga, Luiz Orlando de Oliveira et Michael Lee. « QTL Mapping and Disease Resistance in Cereals ». Journal of New Seeds 2, n^o 2 (18 août 2001) : 1–21. http://dx.doi.org/10.1300/j153v02n02_01.

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Perez-Sackett, P. T., S. R. Cianzio, P. C. Kara, M. Aviles et R. G. Palmer. « QTL Mapping of Whitefly Resistance in Soybean ». Journal of Crop Improvement 25, n^o 2 (30 mars 2011) : 134–50. http://dx.doi.org/10.1080/15427528.2011.546093.

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Bahcall, Orli. « OXA resistance from QTL to crystal structure ». Nature Genetics 46, n^o 1 (27 décembre 2013) : 7. http://dx.doi.org/10.1038/ng.2865.

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Parh, D. K., D. R. Jordan, E. A. B. Aitken, E. S. Mace, P. Jun-ai, C. L. McIntyre et I. D. Godwin. « QTL analysis of ergot resistance in sorghum ». Theoretical and Applied Genetics 117, n^o 3 (15 mai 2008) : 369–82. http://dx.doi.org/10.1007/s00122-008-0781-8.

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