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Genetic map of the Sr2 and Fhb1 regions on chromosome arm 3BS. The markers csSr2 and Xgwm533, and UMN10, and UMN10v2 are used to track Sr2 and Fhb1, respectively. Distances between two adjacent markers on the left of the chromosome are in centiMorgans (cM). The locations of markers of Xgwm389, csSr2, and Xgwm533 are determined in Kota et al. (2006), McNeil et al. (2008), and Mago et al. (2011a, b). The locations of markers UMN10, Xgwm533, and Xgwm493 are reported in Liu et al. (2006, 2008)
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Fusarium head blight (FHB) and stem rust are two devastating fungal diseases of common wheat prevalent worldwide. Fhb1 is a well-known major quantitative trait locus effective against FHB, and Sr2 is the most widely characterized and deployed wheat stem rust adult plant resistance gene. These genes are linked in repulsion phase, approximately 3 cM...
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Fusarium head blight (FHB) is an economically and environmentally concerning disease of wheat (Triticum aestivum L). A two‐pronged approach of marker‐assisted selection coupled with genomic selection has been suggested when breeding for FHB resistance. A historical dataset comprised of entries in the Southern Uniform Winter Wheat Scab Nursery (SUWW...
Achievements and prospects of wheat breeding for disease resistance in the world and in theCzech Republic are discussed. Attention was paid to possibilities of increasing resistance to rusts, powdery mildew, Fusarium head blight, leaf blotch, glume blotch, tan spot, common bunt and barley yellow dwarf virus on wheat. Methodical approaches adopted i...
Citations
... Fhb1 to Fusarium head blight (FHB) and Sr2 to stem rust are valuable resistance genes in wheat; however, these genes are linked in the repulsion phase. Zhang [6] successfully developed elite lines with two genes using diagnostic markers, remarkably promoting wheat resistance breeding. Pina and Pinb are the major genes controlling grain hardness, and when foreground and background selections were performed simultaneously using molecular markers, dozens of BC 2 F 2 soft lines were obtained [7]. ...
Background:
Owing to successful cloning of wheat functional genes in recent years, more traits can be selected by diagnostic markers, and consequently, effective molecular markers will be powerful tools in wheat breeding programs.
Results:
The present study proposed a cost-effective duplex Kompetitive Allele Specific PCR (dKASP) marker system that combined multiplex PCR and KASP™ technology to yield twice the efficiency at half the cost compared with the common KASP™ markers and provide great assistance in breeding selection. Three dKASP markers for the major genes controlling plant height (Rht-B1/Rht-D1), grain hardness (Pina-D1/Pinb-D1), and high-molecular-weight glutenin subunits (Glu-A1/Glu-D1) were successfully developed and applied in approved wheat varieties growing in the middle and lower reaches of the Yangtze River and advanced lines from our breeding program. Three markers were used to test six loci with high efficiency. In the approved wheat varieties, Rht-B1b was the most important dwarfing allele, and the number of accessions carrying Pinb-D1b was much greater than that of the accessions carrying Pina-D1b. Moreover, the number of accessions carrying favorable alleles for weak-gluten wheat (Null/Dx2) was much greater than that of the accessions carrying favorable alleles for strong-gluten wheat (Ax1 or Ax2*/Dx5). In the advanced lines, Rht-B1b and Pinb-D1b showed a significant increase compared with the approved varieties, and the strong-gluten (Ax1 or Ax2*/Dx5) and weak-gluten (Null/Dx2) types also increased.
Conclusion:
A cost-effective dKASP marker system that combined multiplex PCR and KASP™ technology was proposed to achieve double the efficiency at half the cost compared with the common KASP™ markers. Three dKASP markers for the major genes controlling PH (Rht-B1/Rht-D1), GH (Pina-D1/Pinb-D1), and HMW-GS (Glu-A1/Glu-D1) were successfully developed, which would greatly improve the efficiency of marker-assisted selection of wheat.
... However, a major constraint for their combined introduction in advanced germplasm was that these two genes were linked in repulsion phase and in close proximity, approximately 3 cM apart (Anderson et al., 2001). Recently, Zhang et al. (2016) overcame this restriction by developing lines that contain both genes in coupling phase which represents a major breakthrough for breeding for resistance to SR and FHB. ...
... He et al. (2020) reported an SR field severity range of 20-80% and moderately susceptible-susceptible (MSS) to mixed (M) SR responses for lines with the coupled Fhb1-Sr2, while the susceptible (S) check showed 100% severity and susceptible response. Zhang et al. (2016) developed 59 lines carrying Sr2 derived from two different crosses, which had a reduction of SR field severity ranging from 26 to 53% in relation to their susceptible parent. The effect of Sr2 determined in the 'Sf26/Génesis 2375' population was consistent with the effect measured by Zhang et al. (2016). ...
... Zhang et al. (2016) developed 59 lines carrying Sr2 derived from two different crosses, which had a reduction of SR field severity ranging from 26 to 53% in relation to their susceptible parent. The effect of Sr2 determined in the 'Sf26/Génesis 2375' population was consistent with the effect measured by Zhang et al. (2016). ...
Fusarium head blight (FHB) and stem rust (SR) threaten the sustainability of wheat production worldwide. Fhb1 and Sr2 confer partial durable resistance to FHB and SR, respectively. Despite resistant alleles of both genes are linked in repulsion, lines with Fhb1 - Sr2 in coupling were developed at the University of Minnesota, USA. Marker-assisted backcrossing was used to incorporate the coupled Fhb1-Sr2 into four elite INIA-Uruguay spring wheat varieties lacking both genes and expressing different levels of FHB and SR resistance. In each case, the initial cross between the donor line and recurrent parent was backcrossed three times. Genotypes carrying Fhb1-Sr2 were selected using the molecular marker UMN10 . In BC 3 F 3 families, retention of Fhb1-Sr2 was further confirmed with the markers SNP3BS-8 and Sr2-ger9 for Fhb1 and Sr2 , respectively. BC 3 F 3 homozygous lines contrasting at UMN10 , SNP3BS-8 and Sr2-ger9 were obtained to quantify the effect of Fhb1-Sr2 on the resistance to FHB under controlled conditions and to SR under field conditions. After 26 months period, successful introgression of Fhb1-Sr2 into the four cultivars was achieved, representing novel wheat genetic resources. Lines homozygous for the resistant alleles of Fhb1 were significantly more resistant to FHB as reflected by an 18% reduction of average FHB area under the disease progress curve. A significant effect of Sr2 on SR field resistance was observed in lines derived from the most susceptible cultivar ‘Génesis 2375’. The most resistant lines to both diseases are expected to be valuable genetic resources in breeding for durable resistance to FHB and SR.
... Five SNP markers (IWB31002, IWB39832, IWB34324, IWB72894, and IWB36920) were co-segregated with Lr48. The SSR markers sun563 and sun497 were linked with the leaf rust resistance genes Lr48 and Lr13, and the SSR markers Xgwm429 and barc7 were linked with Lr48 [47,48] identified leaf rust resistance genes in wheat cultivars produced in Kazakhstan. They reported that the predictable marker pTAG621 fragment associated with Lr1 was detected in twelve out of 22 wheat cultivars tested. ...
... The markers F1.2245 and Lr10-6/r2, linked to Lr10, were found in only two wheat cultivars. The marker Gb-F and -R fragments specific to Lr19 were detected only in the cultivar Pallada from Russia [48]. The SSR markers Xgwm512 and cfd36 were found to be putatively associated with the leaf rust resistance gene LrM. ...
Background
Thirteen Egyptian wheat cultivars were evaluated and characterized for adult plant resistance to yellow, leaf, and stem rusts. SSR markers linked to yellow, leaf and stem rust resistance genes were validated and subsequently used to identify wheat cultivars containing more than one rust resistance gene.ResultsResults of the molecular marker detection indicated that several genes, either alone or in different combinations, were present among the wheat cultivars, including Yr, Yr78 (stripe rust), Lr, Lr70 (leaf rust), Sr. Sr33, SrTA10187, Sr13, and Sr35 (stem rust), and Lr34/Yr18 and Lr49/Yr29 (leaf/stripe rust). The cultivar Sakha-95 was resistant to leaf and stem rusts, and partially resistant to stripe rust; however, this cultivar contained additional rust resistance genes (Lr, Sr and Lr/Yr). The area under the disease progress curve (AUDPC) type for the various wheat cultivars differed depending on the type of rust infection (yellow, leaf, or stem rust, indicated by Yr, Lr, and Sr). The cultivars Gem-12, Sids-14, Giza-171, and Giza-168 had AUDPC types of partial resistance and resistance. All six cultivars, however, contained additional rust resistance genes.Conclusions
Marker-assisted selection can be applied to improve wheat cultivars with efficient gene combinations that would directly support the development of durable resistance in Egypt. Once the expression of the resistance genes targeted in this study have been confirmed by phenotypic screening, the preferable cultivars can be used as donors by Egyptian wheat breeders. The results of this study will help breeders determine the extent of resistance under field conditions when breeding for rust resistance in bread wheat.
... durum Desf., 2n = 4x = 28, genome AABB). Despite successful identification of novel sources of FHB resistance in hexaploid wheat (He et al., 2013;Osman et al., 2015;Zhang et al., 2016;Ma et al., 2020), their subsequent deployment and usefulness in tetraploid wheat breeding programs have been scarce (Oliver et al., 2007). Therefore, there is an urgent need to identify and implement novel and effective FHB sources of resistance in tetraploid wheat. ...
Hexaploid‐derived resistance genes exhibit complex inheritance and expression patterns in tetraploid backgrounds. This study aimed to characterize the inheritance patterns and genomic compatibilities of hexaploid‐derived Fusarium head blight (FHB) resistance genes in tetraploid durum wheat (Triticum durum Desf.). Evaluation of FHB resistance for F1 hybrids of hexaploid ‘Sumai 3’ crossed with tetraploid and hexaploid wheats indicated that Sumai 3‐derived FHB resistance genes exhibit a dominant phenotypic effect seen only in hexaploid hybrids. Alternately, the hexaploid‐derived FHB resistance genes from PI 277012 exhibited complete dominance in the crosses with both tetraploid and hexaploid wheat. FHB evaluation of the F1 hybrids of Sumai 3 and PI 277012 crossed with ‘Langdon’ (LDN)–‘Chinese Spring’ D‐genome substitution lines suggested that chromosomes 2B, 3B, 4B, 5B, 6B, 3A, 4A, 6A, and 7A contain genes that suppress expression of the Sumai 3‐derived FHB resistance, whereas chromosomes 4A, 6A, and 6B contain genes required for expression of PI 277012‐derived FHB resistance. A wide range of segregation for FHB severity (10–90%) was observed in the F2 generation of Sumai 3 crossed with durum cultivars LDN and ‘Divide’, but the distribution of F3 families derived from the most resistant F2 segregants was skewed towards susceptibility. Similar segregation trends were observed in the crosses of PI 277012 with other durum wheats, whereby FHB resistance became slightly diluted over successive generations. These results suggest tetraploid durum wheat contains the unique alleles at multiple gene loci on different chromosomes that positively and/or negatively regulate the expression of hexaploid‐derived FHB resistance genes, which complicate efforts to deploy these genes in durum breeding programs.
... Five SNP markers (IWB31002, IWB39832, IWB34324, IWB72894, and IWB36920) were co-segregated with Lr48. The SSR markers sun563 and sun497 were linked with the leaf rust resistance genes Lr48 and Lr13, and the SSR markers Xgwm429 and barc7 were linked with Lr48 [47,48] identified leaf rust resistance genes in wheat cultivars produced in Kazakhstan. They reported that the predictable marker pTAG621 fragment associated with Lr1 was detected in twelve out of 22 wheat cultivars tested. ...
... The markers F1.2245 and Lr10-6/r2, linked to Lr10, were found in only two wheat cultivars. The marker Gb-F and -R fragments specific to Lr19 were detected only in the cultivar Pallada from Russia [48]. The SSR markers Xgwm512 and cfd36 were found to be putatively associated with the leaf rust resistance gene LrM. ...
Thirteen Egyptian wheat cultivars were evaluated and characterized for adult plant resistance (APR) to yellow, leaf, and stem rusts. Markers linked to yellow, leaf and stem rust resistance genes were validated and subsequently used to identify wheat cultivars containing more than one rust resistance gene. Results of the molecular marker detection indicated that several genes, either alone or in different combinations, were present among the wheat cultivars, including Yr , Yr78 (stripe rust), Lr , Lr70 (leaf rust), Sr. Sr33 , SrTA10187 , Sr13 , and Sr35 (stem rust), and Lr34/Yr18 and Lr49/Yr29 (leaf/stripe rust). The cultivar Sakha-95 was resistant to leaf and stem rusts, and partially resistant to stripe rust; however, this cultivar contained additional rust resistance genes ( Lr , Sr and Lr/Yr ). The area under the disease progress curve (AUDPC) type for the various wheat cultivars differed depending on the type of rust infection (yellow, leaf, or stem rust, indicated by Yr , Lr , and Sr ). The cultivars Gem-12, Sids-14, Giza-171, and Giza-168 had AUDPC types of partial resistance (PR) and resistance (R). All six cultivars, however, contained additional rust resistance genes.
... Until now, more than 432 quantitative trait loci (QTLs) for FHB resistance have been mapped in wheat (Ma et al., 2020), of which many for type I and type II resistances overlap with QTLs for other types of resistance, indicating the principal roles of type I and type II resistances in controlling FHB. Some of these QTLs have been applied to MASbased FHB resistance improvement with success (Miedaner et al., 2006;Buerstmayr et al., 2009;Xue et al., 2010a;Salameh et al., 2011;Bernardo et al., 2013;Zhang et al., 2016;Jia et al., 2018;Brar et al., 2019a;Li et al., 2019a); however, most of them still require verification due to small effects and large confidence intervals. ...
Wheat production is increasingly threatened by the fungal disease, Fusarium head blight (FHB), caused by Fusarium spp. The introduction of resistant varieties is considered to be an effective measure for containment of this disease. Mapping of FHB-resistance quantitative trait locus (QTL) has promoted marker-assisted breeding for FHB resistance, which has been difficult through traditional breeding due to paucity of resistance genes and quantitative nature of the resistance. The lab of Ma previously cloned Fhb1, which inhibits FHB spread within spikes, and fine mapped Fhb4 and Fhb5, which condition resistance to initial infection of Fusarium spp., from FHB-resistant indigenous line Wangshuibai (WSB). In this study, these three QTLs were simultaneously introduced into five modern Chinese wheat cultivars or lines with different ecological adaptations through marker-assisted backcross in early generations. A total of 14 introgression lines were obtained. All these lines showed significantly improved resistance to the fungal infection and disease spread in 2-year field trials after artificial inoculation. In comparison with the respective recipient lines, the Fhb1, Fhb4, and Fhb5 pyramiding could reduce the disease severity by 95% and did not systematically affect plant height, productive tiller number, kernel number per spike, thousand grain weight, flowering time, and unit yield (without Fusarium inoculation). These results indicated the great value of FHB-resistance QTLs Fhb1, Fhb4, and Fhb5 derived from WSB, and the feasibility and effectiveness of early generation selection for FHB resistance solely based on linked molecular markers.
... Indeed, the combination of multiple minor APR genes forms the basis of the CIMMYT breeding program for rust resistance (Bhavani et al., 2019). Although originally linked in repulsion on chromosome 3B, the Fhb1 and Sr2 genes have been combined to provide a baseline of resistance to both Fusarium head blight and stem rust (Zhang et al., 2016), and the coupled genes have been mobilized in CIMMYT germplasm (He et al., 2020). The use of genetic modification cassettes would avoid the laborious process of developing lines in which genes in repulsion become coupled. ...
Disease resistance (R) gene cloning in wheat (Triticum aestivum) has been accelerated by the recent surge of genomic resources, facilitated by advances in sequencing technologies and bioinformatics. However, with the challenges of population growth and climate change, it is vital not only to clone and functionally characterise a few handfuls of R genes, but to do so at a scale that would facilitate the breeding and deployment of crops that can recognise the wide range of pathogen effectors that threaten agroecosystems. Pathogen populations are continually changing, and breeders must have tools and resources available to rapidly respond to those changes if we are to safeguard our daily bread. To meet this challenge, we propose the creation of a wheat R gene atlas by an international community of researchers and breeders. The atlas would consist of an online directory from which sources of resistance could be identified and deployed to achieve more durable resistance to the major wheat pathogens, such as wheat rusts, blotch diseases, powdery mildew and wheat blast. We present a costed proposal detailing how the interacting molecular components governing disease resistance could be captured from both the host and pathogen through biparental mapping, mutational genomics and whole-genome association genetics. We explore options for the configuration and genotyping of diversity panels of hexaploid and tetraploid wheat, as well as their wild relatives and major pathogens, and discuss how the atlas could inform a dynamic, durable approach to R gene deployment. Set against the current magnitude of wheat yield losses worldwide, recently estimated at 21%, this endeavour presents one route for bringing R genes from the lab to the field at a considerable speed and quantity.
... Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley little to no meiotic recombination occurs between the two, and the undesirable locus is co-inherited with the desirable locus (Choi, 2017). Unfavourable repulsion linkages, where desirable alleles occur on separate homologous chromosome segments but are unable to recombine (for example, Fhb1 and Sr2 on chromosome 3B in wheat; Anderson et al., 2001;Zhang et al., 2016), pose a challenge for introgression of desirable chromosome segments into a different genetic background. Breaking genetic linkage requires meiotic homologous recombination between the two relevant loci. ...
Human population growth has increased the demand for food crops, animal feed, biofuel and biomaterials, all the while climate change is impacting environmental growth conditions. There is an urgent need to develop crop varieties which tolerate adverse growth conditions while requiring fewer inputs. Plant breeding is critical to global food security and, while it has benefited from modern technologies, it remains constrained by a lack of valuable genetic diversity, linkage drag, and an effective way to combine multiple favourable alleles for complex traits. CRISPR/Cas technology has transformed genome editing across biological systems and promises to transform agriculture with its high precision, ease of design, multiplexing ability, and low cost. We discuss the integration of CRISPR/Cas-based gene editing into crop breeding to advance domestication and refine inbred crop varieties for various applications and growth environments. We highlight the use of CRISPR/Cas-based gene editing to fix desirable allelic variants, generate novel alleles, break deleterious genetic linkages, support pre-breeding, and for introgression of favourable loci into elite lines.
... One of the major QTL, Fhb1(Qfhb.ndsu-3BS), which was derived from the Chinese wheat cultivar 'Sumai 3 0 , has been long used for genetic improvement of FHB resistance in wheat (Anderson et al. 2001(Anderson et al. , 2007Buerstmayr et al. 2009;Zhang et al. 2012Zhang et al. , 2016. Furthermore, some other genes/QTL controlling FHB resistance were also identified using SSR markers in wheat such as Fhb2, mapped to the 6B chromosome (Cuthbert et al. 2007 QFhs.inta-7D, on chromosome 7D (Cativelli et al. 2013). ...
In the present study, 25 durum and 25 bread wheat genotypes were evaluated during 2016 and 2017 for Fusarium head blight (FHB) resistance under greenhouse conditions. FHB severity ranged from 10.33% to 94.20%. Highly significant (p < 0.01) genotypes differences were observed, indicating abundant genetic variability. High broad-sense heritability (0.87) and high genetic advance (70.3%) were obtained for FHB severity, suggesting considerable genetic improvement by selection. Of 50 genotypes tested, 6 genotypes showed <20%, 20 genotypes had >50%, and 24 genotypes showed 20–50% disease severity. The most resistant genotypes were BeniSuef-5, Sohag-3, Ciccio, Svevo, WA-88 and Misr-1 with average FHB severity of 10.84, 11.42, 11.49, 14.09, 16.03 and 18.69%, respectively, suggesting the presence of FHB resistance genes. On average, durum wheat genotypes showed lower FHB severity (39.9%) compared to bread wheat (49.1%). Of 18 simple sequence repeat (SSR) markers tested, Xgwm292-5A and Xgwm533-3B could be considered as markers associated with FHB resistance in the tested genotypes. However, further molecular analysis would be performed to confirm their usefulness for marker-assisted selection in wheat breeding programs.
... These results emphasise the difficulty to obtain both Fhb1 and Sr2/Yr30 in the homozygous resistant state. Plants homozygous for both Fhb1 and Sr2/Yr30 were obtained in a study done by Zhang et al. (2016). They reported that 2% of plants in their F 2 population were homozygous for both the Fhb1 and Sr2/Yr30 genes based on results of markers gwm533 and umn10 V2 . ...
Bread wheat is a widely cultivated crop with production that is often negatively influenced by disease outbreaks. Biological constraints in production include the wheat rusts (leaf rust, stem rust and stripe rust) and Fusarium head blight (FHB). Different strategies are available in the control of these important fungal diseases. However, resistance breeding remains the preferred option of control as it lowers the risk of disease outbreaks and is a more cost effective and environmentally friendly approach. Many effective rust and FHB resistance genes have been discovered and successfully deployed through resistance breeding worldwide. However, some of these genes, when deployed singly, are vulnerable to evolving pathogens. In this study we aimed to develop wheat lines with the prospect of durable resistance against the rusts and FHB through combining eight resistance genes/quantitative trait loci; Lr19, Lr34/Yr18/Sr57/Pm38/Ltn1, Sr2/Yr30, Sr26, Sr39, Fhb1, Qfhs.ifa-5A-1 and Qfhs.ifa-5A-2 into a single wheat plant using marker-assisted selection. Cross and self-pollinated populations were developed to increase the frequency and homozygosity levels of resistance genes in progeny. Molecular markers were furthermore applied to determine the identity of the high molecular weight-glutenin subunits (HMW-GS) and to screen for the presence of the 1BL.1RS translocation in the final populations. We were successful in developing wheat plants containing complex sources of rust and FHB resistance and confirmed the presence of HMW-GS markers linked to strong dough strength and good bread making qualities in these genotypes.
