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1.
Philomin Juliana Ravi P. Singh Pawan K. Singh Jesse A. Poland Gary C. Bergstrom Julio Huerta-Espino Sridhar Bhavani Jose Crossa Mark E. Sorrells 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(7):1405-1422
Key message
Genome-wide association mapping in conjunction with population sequencing map and Ensembl plants was used to identify markers/candidate genes linked to leaf rust, stripe rust and tan spot resistance in wheat.Abstract
Leaf rust (LR), stripe rust (YR) and tan spot (TS) are some of the important foliar diseases in wheat (Triticum aestivum L.). To identify candidate resistance genes for these diseases in CIMMYT’s (International Maize and Wheat Improvement Center) International bread wheat screening nurseries, we used genome-wide association studies (GWAS) in conjunction with information from the population sequencing map and Ensembl plants. Wheat entries were genotyped using genotyping-by-sequencing and phenotyped in replicated trials. Using a mixed linear model, we observed that seedling resistance to LR was associated with 12 markers on chromosomes 1DS, 2AS, 2BL, 3B, 4AL, 6AS and 6AL, and seedling resistance to TS was associated with 14 markers on chromosomes 1AS, 2AL, 2BL, 3AS, 3AL, 3B, 6AS and 6AL. Seedling and adult plant resistance (APR) to YR were associated with several markers at the distal end of chromosome 2AS. In addition, YR APR was also associated with markers on chromosomes 2DL, 3B and 7DS. The potential candidate genes for these diseases included several resistance genes, receptor-like serine/threonine-protein kinases and defense-related enzymes. However, extensive LD in wheat that decays at about 5?×?107 bps, poses a huge challenge for delineating candidate gene intervals and candidates should be further mapped, functionally characterized and validated. We also explored a segment on chromosome 2AS associated with multiple disease resistance and identified seventeen disease resistance linked genes. We conclude that identifying candidate genes linked to significant markers in GWAS is feasible in wheat, thus creating opportunities for accelerating molecular breeding.2.
James A. Kolmer Zhenqi Su Amy Bernardo Guihua Bai Shiaoman Chao 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(7):1553-1560
Key message
A new gene for adult plant leaf rust resistance in wheat was mapped to chromosome 3BL. This gene was designated as Lr77.Abstract
‘Santa Fe’ is a hard red winter cultivar that has had long-lasting resistance to the leaf rust fungus, Puccinia triticina. The objective of this study was to determine the chromosome location of the adult plant leaf rust resistance in Santa Fe wheat. A partial backcross line of ‘Thatcher’ (Tc) wheat with adult plant leaf rust resistance derived from Santa Fe was crossed with Thatcher to develop a Thatcher//Tc*2/Santa Fe F6 recombinant inbred line (RIL) population. The RIL population and parental lines were evaluated for segregation of leaf rust resistance in three field plot tests and in an adult plant greenhouse test. A genetic map of the RIL population was constructed using 90,000 single-nucleotide polymorphism (SNP) markers with the Illumina Infinium iSelect 90K wheat bead array. A significant quantitative trait locus for reduction of leaf rust severity in all four tests was found on chromosome 3BL that segregated as a single adult plant resistance gene. The RILs with the allele from the resistant parent for SNP marker IWB10344 had lower leaf rust severity and a moderately resistant to moderately susceptible response compared to the susceptible RILs and Thatcher. The gene derived from Santa Fe on chromosome 3BL was designated as Lr77. Kompetitive allele-specific polymerase chain reaction assay markers linked to Lr77 on 3BL should be useful for selection of wheat germplasm with this gene.3.
Raj K. Pasam Urmil Bansal Hans D. Daetwyler Kerrie L. Forrest Debbie Wong Joanna Petkowski Nicholas Willey Mandeep Randhawa Mumta Chhetri Hanif Miah Josquin Tibbits Harbans Bariana Matthew J. Hayden 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(4):777-793
Key message
BayesR and MLM association mapping approaches in common wheat landraces were used to identify genomic regions conferring resistance to Yr, Lr, and Sr diseases.Abstract
Deployment of rust resistant cultivars is the most economically effective and environmentally friendly strategy to control rust diseases in wheat. However, the highly evolving nature of wheat rust pathogens demands continued identification, characterization, and transfer of new resistance alleles into new varieties to achieve durable rust control. In this study, we undertook genome-wide association studies (GWAS) using a mixed linear model (MLM) and the Bayesian multilocus method (BayesR) to identify QTL contributing to leaf rust (Lr), stem rust (Sr), and stripe rust (Yr) resistance. Our study included 676 pre-Green Revolution common wheat landrace accessions collected in the 1920–1930s by A.E. Watkins. We show that both methods produce similar results, although BayesR had reduced background signals, enabling clearer definition of QTL positions. For the three rust diseases, we found 5 (Lr), 14 (Yr), and 11 (Sr) SNPs significant in both methods above stringent false-discovery rate thresholds. Validation of marker–trait associations with known rust QTL from the literature and additional genotypic and phenotypic characterisation of biparental populations showed that the landraces harbour both previously mapped and potentially new genes for resistance to rust diseases. Our results demonstrate that pre-Green Revolution landraces provide a rich source of genes to increase genetic diversity for rust resistance to facilitate the development of wheat varieties with more durable rust resistance.4.
Weizhen Liu Marco Maccaferri Peter Bulli Sheri Rynearson Roberto Tuberosa Xianming Chen Michael Pumphrey 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(4):649-667
Key message
Genome-wide association analysis in tetraploid wheat revealed novel and diverse loci for seedling and field resistance to stripe rust in elite spring durum wheat accessions from worldwide.Abstract
Improving resistance to stripe rust, caused by Puccinia striiformis f. sp. tritici, is a major objective for wheat breeding. To identify effective stripe rust resistance loci, a genome-wide association study (GWAS) was conducted using 232 elite durum wheat (Triticum turgidum ssp. durum) lines from worldwide breeding programs. Genotyping with the 90 K iSelect wheat single nucleotide polymorphism (SNP) array resulted in 11,635 markers distributed across the genome. Response to stripe rust infection at the seedling stage revealed resistant and susceptible accessions present in rather balanced frequencies for the six tested races, with a higher frequency of susceptible responses to United States races as compared to Italian races (61.1 vs. 43.1% of susceptible accessions). Resistance at the seedling stage only partially explained adult plant resistance, which was found to be more frequent with 67.7% of accessions resistant across six nurseries in the United States. GWAS identified 82 loci associated with seedling stripe rust resistance, five of which were significant at the false discovery rate adjusted P value <0.1 and 11 loci were detected for the field response at the adult plant stages in at least two environments. Notably, Yrdurum-1BS.1 showed the largest effect for both seedling and field resistance, and is therefore considered as a major locus for resistance in tetraploid wheat. Our GWAS study is the first of its kind for stripe rust resistance in tetraploid wheat and provides an overview of resistance in elite germplasm and reports new loci that can be used in breeding resistant cultivars.5.
Weizhen Liu Marco Maccaferri Xianming Chen Gaetano Laghetti Domenico Pignone Michael Pumphrey Roberto Tuberosa 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(11):2249-2270
Key message
SNP-based genome scanning in worldwide domesticated emmer germplasm showed high genetic diversity, rapid linkage disequilibrium decay and 51 loci for stripe rust resistance, a large proportion of which were novel.Abstract
Cultivated emmer wheat (Triticum turgidum ssp. dicoccum), one of the oldest domesticated crops in the world, is a potentially rich reservoir of variation for improvement of resistance/tolerance to biotic and abiotic stresses in wheat. Resistance to stripe rust (Puccinia striiformis f. sp. tritici) in emmer wheat has been under-investigated. Here, we employed genome-wide association (GWAS) mapping with a mixed linear model to dissect effective stripe rust resistance loci in a worldwide collection of 176 cultivated emmer wheat accessions. Adult plants were tested in six environments and seedlings were evaluated with five races from the United States and one from Italy under greenhouse conditions. Five accessions were resistant across all experiments. The panel was genotyped with the wheat 90,000 Illumina iSelect single nucleotide polymorphism (SNP) array and 5106 polymorphic SNP markers with mapped positions were obtained. A high level of genetic diversity and fast linkage disequilibrium decay were observed. In total, we identified 14 loci associated with field resistance in multiple environments. Thirty-seven loci were significantly associated with all-stage (seedling) resistance and six of them were effective against multiple races. Of the 51 total loci, 29 were mapped distantly from previously reported stripe rust resistance genes or quantitative trait loci and represent newly discovered resistance loci. Our results suggest that GWAS is an effective method for characterizing genes in cultivated emmer wheat and confirm that emmer wheat is a rich source of stripe rust resistance loci that can be used for wheat improvement.6.
Jyoti Singla Linda Lüthi Thomas Wicker Urmil Bansal Simon G. Krattinger Beat Keller 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(1):1-12
Key message
Here, we describe a strategy to improve broad-spectrum leaf rust resistance by marker-assisted combination of two partial resistance genes. One of them represents a novel partial adult plant resistance gene, named Lr75.Abstract
Leaf rust caused by the fungal pathogen Puccinia triticina is a damaging disease of wheat (Triticum aestivum L.). The combination of several, additively-acting partial disease resistance genes has been proposed as a suitable strategy to breed wheat cultivars with high levels of durable field resistance. The Swiss winter wheat cultivar ‘Forno’ continues to show near-immunity to leaf rust since its release in the 1980s. This resistance is conferred by the presence of at least six quantitative trait loci (QTL), one of which is associated with the morphological trait leaf tip necrosis. Here, we used a marker-informed strategy to introgress two ‘Forno’ QTLs into the leaf rust-susceptible Swiss winter wheat cultivar ‘Arina’. The resulting backcross line ‘ArinaLrFor’ showed markedly increased leaf rust resistance in multiple locations over several years. One of the introgressed QTLs, QLr.sfr-1BS, is located on chromosome 1BS. We developed chromosome 1B-specific microsatellite markers by exploiting the Illumina survey sequences of wheat cv. ‘Chinese Spring’ and mapped QLr.sfr-1BS to a 4.3 cM interval flanked by the SSR markers gwm604 and swm271. QLr.sfr-1BS does not share a genetic location with any of the described leaf rust resistance genes present on chromosome 1B. Therefore, QLr.sfr-1BS is novel and was designated as Lr75. We conclude that marker-assisted combination of partial resistance genes is a feasible strategy to increase broad-spectrum leaf rust resistance. The identification of Lr75 adds a novel and highly useful gene to the small set of known partial, adult plant leaf rust resistance genes.7.
Guotai Yu Nicolas Champouret Burkhard Steuernagel Pablo D. Olivera Jamie Simmons Cole Williams Ryan Johnson Matthew J. Moscou Inmaculada Hernández-Pinzón Phon Green Hanan Sela Eitan Millet Jonathan D. G. Jones Eric R. Ward Brian J. Steffenson Brande B. H. Wulff 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(6):1207-1222
Key message
We identified two novel wheat stem rust resistance genes, Sr-1644-1Sh and Sr-1644-5Sh in Aegilops sharonensis that are effective against widely virulent African races of the wheat stem rust pathogen.Abstract
Stem rust is one of the most important diseases of wheat in the world. When single stem rust resistance (Sr) genes are deployed in wheat, they are often rapidly overcome by the pathogen. To this end, we initiated a search for novel sources of resistance in diverse wheat relatives and identified the wild goatgrass species Aegilops sharonesis (Sharon goatgrass) as a rich reservoir of resistance to wheat stem rust. The objectives of this study were to discover and map novel Sr genes in Ae. sharonensis and to explore the possibility of identifying new Sr genes by genome-wide association study (GWAS). We developed two biparental populations between resistant and susceptible accessions of Ae. sharonensis and performed QTL and linkage analysis. In an F6 recombinant inbred line and an F2 population, two genes were identified that mapped to the short arm of chromosome 1Ssh, designated as Sr-1644-1Sh, and the long arm of chromosome 5Ssh, designated as Sr-1644-5Sh. The gene Sr-1644-1Sh confers a high level of resistance to race TTKSK (a member of the Ug99 race group), while the gene Sr-1644-5Sh conditions strong resistance to TRTTF, another widely virulent race found in Yemen. Additionally, GWAS was conducted on 125 diverse Ae. sharonensis accessions for stem rust resistance. The gene Sr-1644-1Sh was detected by GWAS, while Sr-1644-5Sh was not detected, indicating that the effectiveness of GWAS might be affected by marker density, population structure, low allele frequency and other factors.8.
QTL mapping of Fusarium head blight resistance in three related durum wheat populations 总被引:2,自引:0,他引:2
Noemie Prat Camille Guilbert Ursa Prah Elisabeth Wachter Barbara Steiner Thierry Langin Olivier Robert Hermann Buerstmayr 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(1):13-27
Key message
The QTL Fhb1 was successfully introgressed and validated in three durum wheat populations. The novel germplasm and the QTL detected will support improvement of Fusarium resistance in durum wheat.Abstract
Durum wheat (Triticum durum Desf.) is particularly susceptible to Fusarium head blight (FHB) and breeding for resistance is hampered by limited genetic variation within this species. To date, resistant sources are mainly available in a few wild relative tetraploid wheat accessions. In this study, the effect of the well-known hexaploid wheat (Triticum aestivum L.) quantitative trait locus (QTL) Fhb1 was assessed for the first time in durum wheat. Three F7-RIL mapping populations of about 100 lines were developed from crosses between the durum wheat experimental line DBC-480, which carries an Fhb1 introgression from Sumai-3, and the European T. durum cultivars Karur, Durobonus and SZD1029K. The RILs were evaluated in field experiments for FHB resistance in three seasons using spray inoculation and genotyped with SSR as well as genotyping-by-sequencing markers. QTL associated with FHB resistance were identified on chromosome arms 2BL, 3BS, 4AL, 4BS, 5AL and 6AS at which the resistant parent DBC-480 contributed the positive alleles. The QTL on 3BS was detected in all three populations centered at the Fhb1 interval. The Rht-B1 locus governing plant height was found to have a strong effect in modulating FHB severity in all populations. The negative effect of the semi-dwarf allele Rht-B1b on FHB resistance was compensated by combining with Fhb1 and additional resistance QTL. The successful deployment of Fhb1 in T. durum was further substantiated by assessing type 2 resistance in one population. The efficient introgression of Fhb1 represents a significant step forward for enhancing FHB resistance in durum wheat.9.
Hongbing She Wei Qian Helong Zhang Zhiyuan Liu Xiaowu Wang Jian Wu Chunda Feng James C. Correll Zhaosheng Xu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(12):2529-2541
Key message
A SLAF-BSA approach was used to locate the RPF1 locus. The three most likely candidate genes were identified which provide a basic for cloning the resistance gene at the RPF1 locus.Abstract
Spinach downy mildew is a globally devastating oomycete disease. The use of downy mildew resistance genes constitutes the most effective approach for disease management. Hence, the objective of the present study was to fine map the first-reported resistance locus RPF1. The resistance allele at this resistance locus was effective against races 1–7, 9, 11, 13, and 15 of Peronospora farinosa f. sp. spinaciae (P. effusa). The approach fine mapped RPF1 using specific-locus amplified fragment sequencing (SLAF-Seq) technology combined with bulked segregant analysis. A 1.72 Mb region localized on chromosome 3 was found to contain RPF1 based on association analysis. After screening recombinants with the SLAF markers within the region, the region was narrowed down to 0.89 Mb. Within this region, 14 R genes were identified based on the annotation information. To identify the genes involved in resistance, resequencing of two resistant inbred lines (12S2 and 12S3) and three susceptible inbred lines (12S1, 12S4, and 10S2) was performed. The three most likely candidate genes were identified via amino acid sequence analysis and conserved domain analysis between resistant and susceptible inbred lines. These included Spo12729, encoding a receptor-like protein, and Spo12784 and Spo12903, encoding a nucleotide-binding site and leucine-rich repeat domains. Additionally, based on the sequence variation in the three genes between the resistant and susceptible lines, molecular markers were developed for marker-assisted selection. The results could be valuable in cloning the RPF1 alleles and improving our understanding of the interaction between the host and pathogen.10.
Xinyi Wu Guojing Li Baogen Wang Yaowen Hu Xiaohua Wu Ying Wang Zhongfu Lu Pei Xu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(12):2709-2718
Key message
A new rust resistance gene Ruv2 was fine-mapped in cowpea to a 193-kb region on chromosome 2, which harboured 23 predicted gene models enriched with NBS-type genes.Abstract
ZN016 is a landrace vegetable cowpea highly resistant to rust. Two previous studies using mixed-spores inoculation suggested different modes of inheritance of rust resistance in ZN016. In this study, we initially developed a detached leaf assay with a purified single-rust isolate (Auv-LS). Using this approach, we assessed the inheritance of rust resistance in a recombinant inbred line (RIL) population and an F2 population, both derived from the cross of “ZN016” and the susceptible cultivar “Zhijiang282.” A single dominant gene mode against Auv-LS was revealed in both populations. QTL mapping showed that this gene was coincident with the Ruv2 locus on LG7, one of the three resistance QTLs previously mapped based on mixed-spores inoculation data. Therefore, Ruv2 was considered as specifically against the rust isolate Auv-LS. Through an analysis of the RIL recombinants at Ruv2, we fine-mapped the gene to an ~?0.45-cM interval between SNP markers 2_09656 and 2_00973, which corresponded to an ~?193-kb region on chromosome 2 that harboured 23 predicted gene models enriched with NBS-type genes. Re-sequencing of the two parents revealed polymorphisms in four genes predictively to cause substantial protein structural changes, rendering them valuable candidate genes for future validation. Cross-species syntenic analysis indicated that Ruv2 may represent a novel rust resistance gene in food legumes. A cleaved amplified polymorphic sequences marker tightly linked to Ruv2 was developed to facilitate breeding. This work establishes a basis for map-based cloning of Ruv2 and breeding for rust resistance in cowpea and other legume crops.11.
Firdissa E. Bokore Richard D. Cuthbert Ron E. Knox Harpinder S. Randhawa Colin W. Hiebert Ron M. DePauw Asheesh K. Singh Arti Singh Andrew G. Sharpe Amidou N’Diaye Curtis J. Pozniak Curt McCartney Yuefeng Ruan Samia Berraies Brad Meyer Catherine Munro Andy Hay Karim Ammar Julio Huerta-Espino Sridhar Bhavani 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(12):2617-2635
Key message
Quantitative trait loci controlling stripe rust resistance were identified in adapted Canadian spring wheat cultivars providing opportunity for breeders to stack loci using marker-assisted breeding.Abstract
Stripe rust or yellow rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss., is a devastating disease of common wheat (Triticum aestivum L.) in many regions of the world. The objectives of this research were to identify and map quantitative trait loci (QTL) associated with stripe rust resistance in adapted Canadian spring wheat cultivars that are effective globally, and investigate opportunities for stacking resistance. Doubled haploid (DH) populations from the crosses Vesper/Lillian, Vesper/Stettler, Carberry/Vesper, Stettler/Red Fife and Carberry/AC Cadillac were phenotyped for stripe rust severity and infection response in field nurseries in Canada (Lethbridge and Swift Current), New Zealand (Lincoln), Mexico (Toluca) and Kenya (Njoro), and genotyped with SNP markers. Six QTL for stripe rust resistance in the population of Vesper/Lillian, five in Vesper/Stettler, seven in Stettler/Red Fife, four in Carberry/Vesper and nine in Carberry/AC Cadillac were identified. Lillian contributed stripe rust resistance QTL on chromosomes 4B, 5A, 6B and 7D, AC Cadillac on 2A, 2B, 3B and 5B, Carberry on 1A, 1B, 4A, 4B, 7A and 7D, Stettler on 1A, 2A, 3D, 4A, 5B and 6A, Red Fife on 2D, 3B and 4B, and Vesper on 1B, 2B and 7A. QTL on 1A, 1B, 2A, 2B, 3B, 4A, 4B, 5B, 7A and 7D were observed in multiple parents. The populations are compelling sources of recombination of many stripe rust resistance QTL for stacking disease resistance. Gene pyramiding should be possible with little chance of linkage drag of detrimental genes as the source parents were mostly adapted cultivars widely grown in Canada.12.
M. Kathryn Turner James A. Kolmer Michael O. Pumphrey Peter Bulli Shiaoman Chao James A. Anderson 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(2):345-361
Key message
We identified 15 potentially novel loci in addition to previously characterized leaf rust resistance genes from 1032 spring wheat accessions. Targeted AM subset panels were instrumental in revealing interesting loci.Abstract
Leaf rust is a common disease of wheat, consistently reducing yields in many wheat-growing regions of the world. Although fungicides are commonly applied to wheat in the United States (US), genetic resistance can provide less expensive, yet effective control of the disease. Our objectives were to map leaf rust resistance genes in a large core collection of spring wheat accessions selected from the United States Department of Agriculture-Agricultural Research Service National Small Grains Collection (NSGC), determine whether previously characterized race-nonspecific resistance genes could be identified with our panel, and evaluate the use of targeted panels to identify seedling and adult plant resistance (APR) genes. Association mapping (AM) detected five potentially novel leaf rust resistance loci on chromosomes 2BL, 4AS, and 5DL at the seedling stage, and 2DL and 7AS that conditioned both seedling and adult plant resistance. In addition, ten potentially novel race-nonspecific resistance loci conditioned field resistance and lacked seedling resistance. Analyses of targeted subsets of the accessions identified additional loci not associated with resistance in the complete core panel. Using molecular markers, we also confirmed the presence and effectiveness of the race-nonspecific genes Lr34, Lr46, and Lr67 in our panel. Although most of the accessions in this study were susceptible to leaf rust in field and seedling tests, many resistance loci were identified with AM. Through the use of targeted subset panels, more loci were identified than in the larger core panels alone.13.
Yan Holtz Michel Bonnefoy Véronique Viader Morgane Ardisson Nicolas O. Rode Gérard Poux Pierre Roumet Véronique Marie-Jeanne Vincent Ranwez Sylvain Santoni David Gouache Jacques L. David 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(7):1491-1505
Key message
The resistance of durum wheat to the Wheat spindle streak mosaic virus (WSSMV) is controlled by two main QTLs on chromosomes 7A and 7B, with a huge epistatic effect.Abstract
Wheat spindle streak mosaic virus (WSSMV) is a major disease of durum wheat in Europe and North America. Breeding WSSMV-resistant cultivars is currently the only way to control the virus since no treatment is available. This paper reports studies of the inheritance of WSSMV resistance using two related durum wheat populations obtained by crossing two elite cultivars with a WSSMV-resistant emmer cultivar. In 2012 and 2015, 354 recombinant inbred lines (RIL) were phenotyped using visual notations, ELISA and qPCR and genotyped using locus targeted capture and sequencing. This allowed us to build a consensus genetic map of 8568 markers and identify three chromosomal regions involved in WSSMV resistance. Two major regions (located on chromosomes 7A and 7B) jointly explain, on the basis of epistatic interactions, up to 43% of the phenotypic variation. Flanking sequences of our genetic markers are provided to facilitate future marker-assisted selection of WSSMV-resistant cultivars.14.
Adnan Riaz Naveenkumar Athiyannan Sambasivam K. Periyannan Olga Afanasenko Olga P. Mitrofanova Gregory J. Platz Elizabeth A. B. Aitken Rod J. Snowdon Evans S. Lagudah Lee T. Hickey Kai P. Voss-Fels 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(1):127-144
Key message
Thirteen potentially new leaf rust resistance loci were identified in a Vavilov wheat diversity panel. We demonstrated the potential of allele stacking to strengthen resistance against this important pathogen.Abstract
Leaf rust (LR) caused by Puccinia triticina is an important disease of wheat (Triticum aestivum L.), and the deployment of genetically resistant cultivars is the most viable strategy to minimise yield losses. In this study, we evaluated a diversity panel of 295 bread wheat accessions from the N. I. Vavilov Institute of Plant Genetic Resources (St Petersburg, Russia) for LR resistance and performed genome-wide association studies (GWAS) using 10,748 polymorphic DArT-seq markers. The diversity panel was evaluated at seedling and adult plant growth stages using three P. triticina pathotypes prevalent in Australia. GWAS was applied to 11 phenotypic data sets which identified a total of 52 significant marker–trait associations representing 31 quantitative trait loci (QTL). Among them, 29 QTL were associated with adult plant resistance (APR). Of the 31 QTL, 13 were considered potentially new loci, whereas 4 co-located with previously catalogued Lr genes and 14 aligned to regions reported in other GWAS and genomic prediction studies. One seedling LR resistance QTL located on chromosome 3A showed pronounced levels of linkage disequilibrium among markers (r 2 = 0.7), suggested a high allelic fixation. Subsequent haplotype analysis for this region found seven haplotype variants, of which two were strongly associated with LR resistance at seedling stage. Similarly, analysis of an APR QTL on chromosome 7B revealed 22 variants, of which 4 were associated with resistance at the adult plant stage. Furthermore, most of the tested lines in the diversity panel carried 10 or more combined resistance-associated marker alleles, highlighting the potential of allele stacking for long-lasting resistance.15.
Romel Gonzales-Salazar Bianca Cecere Michelina Ruocco Rosa Rao Giandomenico Corrado 《Biotechnology letters》2017,39(7):1049-1058
Objectives
To engineer broad spectrum resistance in potato using different expression strategies.Results
The previously identified Ribosome-Inactivating Protein from Phytolacca heterotepala was expressed in potato under a constitutive or a wound-inducible promoter. Leaves and tubers of the plants constitutively expressing the transgene were resistant to Botrytis cinerea and Rhizoctonia solani, respectively. The wound-inducible promoter was useful in driving the expression upon wounding and fungal damage, and conferred resistance to B. cinerea. The observed differences between the expression strategies are discussed considering the benefits and features offered by the two systems.Conclusions
Evidence is provided of the possible impact of promoter sequences to engineer BSR in plants, highlighting that the selection of a suitable expression strategy has to balance specific needs and target species.16.
Jianhui Wu Shuo Huang Qingdong Zeng Shengjie Liu Qilin Wang Jingmei Mu Shizhou Yu Dejun Han Zhensheng Kang 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(8):1777-1792
Key message
A major stripe rust resistance QTL on chromosome 4BL was localized to a 4.5-Mb interval using comparative QTL mapping methods and validated in 276 wheat genotypes by haplotype analysis.Abstract
CYMMIT-derived wheat line P10103 was previously identified to have adult plant resistance (APR) to stripe rust in the greenhouse and field. The conventional approach for QTL mapping in common wheat is laborious. Here, we performed QTL detection of APR using a combination of genome-wide scanning and extreme pool-genotyping. SNP-based genetic maps were constructed using the Wheat55 K SNP array to genotype a recombinant inbred line (RIL) population derived from the cross Mingxian 169?×?P10103. Five stable QTL were detected across multiple environments. After comparing SNP profiles from contrasting, extreme DNA pools of RILs six putative QTL were located to approximate chromosome positions. A major QTL on chromosome 4B was identified in F2:4 contrasting pools from cross Zhengmai 9023?×?P10103. A consensus QTL (LOD?=?26–40, PVE?=?42–55%), named QYr.nwafu-4BL, was defined and localized to a 4.5-Mb interval flanked by SNP markers AX-110963704 and AX-110519862 in chromosome arm 4BL. Based on stripe rust response, marker genotypes, pedigree analysis and mapping data, QYr.nwafu-4BL is likely to be a new APR QTL. The applicability of the SNP-based markers flanking QYr.nwafu-4BL was validated on a diversity panel of 276 wheat lines. The additional minor QTL on chromosomes 4A, 5A, 5B and 6A enhanced the level of resistance conferred by QYr.nwafu-4BL. Marker-assisted pyramiding of QYr.nwafu-4BL and other favorable minor QTL in new wheat cultivars should improve the level of APR to stripe rust.17.
Dominik Losert Hans Peter Maurer Willmar L. Leiser Tobias Würschum 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(4):685-696
Key message
Genome-wide association mapping of resistance against the novel, aggressive ‘Warrior’ race of yellow rust in triticale revealed a genetic architecture with some medium-effect QTL and a quantitative component, which in combination confer high levels of resistance on both leaves and ears.Abstract
Yellow rust is an important destructive fungal disease in small grain cereals and the exotic ‘Warrior’ race has recently conquered Europe. The aim of this study was to investigate the genetic architecture of yellow rust resistance in hexaploid winter triticale as the basis for a successful resistance breeding. To this end, a diverse panel of 919 genotypes was evaluated for yellow rust infection on leaves and ears in multi-location field trials and genotyped by genotyping-by-sequencing as well as for known Yr resistance loci. Genome-wide association mapping identified ten quantitative trait loci (QTL) for yellow rust resistance on the leaves and seven of these also for ear resistance. The total genotypic variance explained by the QTL amounted to 44.0% for leaf and 26.0% for ear resistance. The same three medium-effect QTL were identified for both traits on chromosomes 1B, 2B, and 7B. Interestingly, plants pyramiding the resistance allele of all three medium-effect QTL were generally most resistant, but constitute less than 5% of the investigated triticale breeding material. Nevertheless, a genome-wide prediction yielded a higher predictive ability than prediction based on these three QTL. Taken together, our results show that yellow rust resistance in winter triticale is genetically complex, including both medium-effect QTL as well as a quantitative resistance component. Resistance to the novel ‘Warrior’ race of this fungal pathogen is consequently best achieved by recurrent selection in the field based on identified resistant lines and can potentially be assisted by genomic approaches.18.
G. J. Ma Q. J. Song S. G. Markell L. L. Qi 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(7):1423-1432
Key message
A novel rust resistance gene, R 15 , derived from the cultivated sunflower HA-R8 was assigned to linkage group 8 of the sunflower genome using a genotyping-by-sequencing approach. SNP markers closely linked to R 15 were identified, facilitating marker-assisted selection of resistance genes.Abstract
The rust virulence gene is co-evolving with the resistance gene in sunflower, leading to the emergence of new physiologic pathotypes. This presents a continuous threat to the sunflower crop necessitating the development of resistant sunflower hybrids providing a more efficient, durable, and environmentally friendly host plant resistance. The inbred line HA-R8 carries a gene conferring resistance to all known races of the rust pathogen in North America and can be used as a broad-spectrum resistance resource. Based on phenotypic assessments of 140 F2 individuals derived from a cross of HA 89 with HA-R8, rust resistance in the population was found to be conferred by a single dominant gene (R 15 ) originating from HA-R8. Genotypic analysis with the currently available SSR markers failed to find any association between rust resistance and any markers. Therefore, we used genotyping-by-sequencing (GBS) analysis to achieve better genomic coverage. The GBS data showed that R 15 was located at the top end of linkage group (LG) 8. Saturation with 71 previously mapped SNP markers selected within this region further showed that it was located in a resistance gene cluster on LG8, and mapped to a 1.0-cM region between three co-segregating SNP makers SFW01920, SFW00128, and SFW05824 as well as the NSA_008457 SNP marker. These closely linked markers will facilitate marker-assisted selection and breeding in sunflower.19.
Carla Ceoloni Paola Forte Ljiljana Kuzmanović Silvio Tundo Ilaria Moscetti Pasquale De Vita Maria Elena Virili Renato D’Ovidio 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(10):2005-2024
Key message
A major locus for resistance to different Fusarium diseases was mapped to the most distal end of Th. elongatum 7EL and pyramided with Th. ponticum beneficial genes onto wheat 7DL.Abstract
Perennial Triticeae species of the Thinopyrum genus are among the richest sources of valuable genes/QTL for wheat improvement. One notable and yet unexploited attribute is the exceptionally effective resistance to a major wheat disease worldwide, Fusarium head blight, associated with the long arm of Thinopyrum elongatum chromosome 7E (7EL). We targeted the transfer of the temporarily designated Fhb-7EL locus into bread wheat, pyramiding it with a Th. ponticum 7el1L segment stably inserted into the 7DL arm of wheat line T4. Desirable genes/QTL mapped along the T4 7el1L segment determine resistance to wheat rusts (Lr19, Sr25) and enhancement of yield-related traits. Mapping of the Fhb-7EL QTL, prerequisite for successful pyramiding, was established here on the basis of a bioassay with Fusarium graminearum of different 7EL-7el1L bread wheat recombinant lines. These were obtained without resorting to any genetic pairing promotion, but relying on the close 7EL-7el1L homoeology, resulting in 20% pairing frequency between the two arms. Fhb-7EL resided in the telomeric portion and resistant recombinants could be isolated with useful combinations of more proximally located 7el1L genes/QTL. The transferred Fhb-7EL locus was shown to reduce disease severity and fungal biomass in grains of infected recombinants by over 95%. The same Fhb-7EL was, for the first time, proved to be effective also against F. culmorum and F. pseudograminearum, predominant agents of crown rot. Prebreeding lines possessing a suitable 7EL-7el1L gene/QTL assembly showed very promising yield performance in preliminary field tests.20.
Yong Wang Jingzhong Xie Huaizhi Zhang Bingmin Guo Shunzong Ning Yongxing Chen Ping Lu Qiuhong Wu Miaomiao Li Deyun Zhang Guanghao Guo Yan Zhang Dengcai Liu Shaokui Zou Jianwei Tang Hong Zhao Xicheng Wang Jun Li Wuyun Yang Tingjie Cao Guihong Yin Zhiyong Liu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(10):2191-2201