Mapping spot blotch resistance genes in four barley populations

Bipolaris sorokiniana (teleomorph: Cochliobolus sativus) is the fungal pathogen responsible for spot blotch in barley (Hordeum vulgare L.) and occurs worldwide in warmer, humid growing conditions. Current Australian barley varieties are largely susceptible to this disease and attempts are being made to introduce sources of resistance from North America. In this study we have compared chromosomal locations of spot blotch resistance reactions in four North American two-rowed barley lines; the North Dakota lines ND11231-12 and ND11231-11 and the Canadian lines TR251 and WPG8412-9-2-1. Diversity arrays technology-based PCR, expressed sequence tag and SSR markers have been mapped across four populations derived from crosses between susceptible parental lines and these four resistant parents to determine the location of resistance loci. Quantitative trait loci (QTL) conferring resistance to spot blotch in adult plants (APR) were detected on chromosomes 3HS and 7HS. In contrast, seedling resistance (SLR) was controlled solely by a locus on chromosome 7HS. The phenotypic variance explained by the APR QTL on 3HS was between 16 and 25% and the phenotypic variance explained by the 7HS APR QTL was between 8 and 42% across the four populations. The SLR QTL on 7HS explained between 52 and 64% of the phenotypic variance. An examination of the pedigrees of these resistance sources supports the common identity of resistance in these lines and indicates that only a limited number of major resistance loci are available in current two-rowed germplasm.     

Genome-wide association mapping reveals genetic architecture of durable spot blotch resistance in US barley breeding germplasm

Spot blotch, an economically important disease of both barley and wheat, is caused by Cochliobolus sativus (anamorph: Bipolaris sorokiniana). The disease has been reported in many regions of the world, but is particularly severe on barley in the Upper Midwest region of the USA and adjacent areas of Canada. For over 50 years, spot blotch has been effectively controlled through the deployment of durable resistance in six-rowed malting cultivars. To characterize loci conferring spot blotch resistance in US barley germplasm, we employed an association mapping approach using 3,840 breeding lines and cultivars. Three quantitative trait loci (QTL), Rcs-qtl-1H-11_10764, Rcs-qtl-3H-11_10565 and Rcs-qtl-7H-11_20162, were found to confer both seedling and adult plant resistance. Together, these three QTL comprise the Midwest Six-rowed Durable Resistant Haplotype (MSDRH), which is present in all Midwest six-rowed cultivars released since the 1960s. Each QTL alone only partially reduced disease levels, but combining all three together reduced the seedling infection response and adult plant disease severity by 47 and 83 %, respectively. The identified MSDRH will be valuable for marker-assisted selection of breeding lines to deploy spot blotch resistance and can also be incorporated into genomic selection as one of the disease resistance traits.     

Mapping quantitative trait loci associated with spot blotch and net blotch resistance in a doubled-haploid barley population

Spot blotch and net blotch are important foliar barley (Hordeum vulgare L.) diseases in Canada and elsewhere. These diseases result in significant yield reduction and, more importantly, loss of grain quality, downgrading barley from malt to feed. Combining resistance to these diseases is a breeding priority but is a significant challenge using conventional breeding methodology. In the present investigation, an evaluation of the inheritance of resistance to spot and net blotch was conducted in a doubled-haploid barley population from the cross CDC Bold (susceptible)?×?TR251 (resistant). The population was screened at the seedling stage in the Phytotron and at the adult-plant stage in the field for several years. Chi-squared analysis indicated one- to four-gene segregation depending on disease, isolate, plant development stage, location and year. A major seedling and adult-plant resistance quantitative trait locus (QTL), designated QRpt6, was re-confirmed for net-form net blotch resistance, explaining 32?C61% of phenotypic variation in different experiments. Additional QTL for seedling and adult-plant resistance to net blotch were identified. For spot blotch resistance, a major seedling resistance QTL (QRcss1) was detected on chromosome 1H for isolate WRS1909, explaining 79% of the phenotypic variation. A highly significant QTL on 3H (QRcs3) was identified for seedling resistance to isolate WRS1908 and adult-plant resistance at Brandon, MB, Canada in 2008. The identification of QTL at only one location or from 1?year suggests spot blotch resistance is complex and highly influenced by the environment. Efforts are being made to combine spot and net blotch resistance in elite barley lines using molecular marker-assisted selection.     

Association mapping utilizing diverse barley lines reveals net form net blotch seedling resistance/susceptibility loci

Key message

A diverse collection of barley lines was phenotyped with three North American Pyrenophora teres f. teres isolates and association analyses detected 78 significant marker-trait associations at 16 genomic loci.

Abstract

Pyrenophora teres f. teres is a necrotrophic fungal pathogen and the causal agent of the economically important foliar disease net form net blotch (NFNB) of barley. The deployment of effective and durable resistance against P. teres f. teres has been hindered by the complexity of quantitative resistance and susceptibility. Several bi-parental mapping populations have been used to identify QTL associated with NFNB disease on all seven barley chromosomes. Here, we report the first genome-wide association study (GWAS) to detect marker-trait associations for resistance or susceptibility to P. teres f. teres. Geographically diverse barley genotypes from a world barley core collection (957) were genotyped with the Illumina barley iSelect chip and phenotyped with three P. teres f. teres isolates collected in two geographical regions of the USA (15A, 6A and LDNH04Ptt19). The best of nine regression models tested were identified for each isolate and used for association analysis resulting in the identification of 78 significant marker-trait associations (MTA; ?log10p value?>3.0). The MTA identified corresponded to 16 unique genomic loci as determined by analysis of local linkage disequilibrium between markers that did not meet a correlation threshold of R ²?≥?0.1, indicating that the markers represented distinct loci. Five loci identified represent novel QTL and were designated QRptts-3HL, QRptts-4HS, QRptts-5HL.1, QRptts-5HL.2, and QRptts-7HL.1. In addition, 55 of the barley lines examined exhibited a high level of resistance to all three isolates and the SNP markers identified will provide useful genetic resources for barley breeding programs.

     

Comprehensive genetic analyses reveal differential expression of spot blotch resistance in four populations of barley

Spot blotch, caused by Cochliobolus sativus, is an important disease of barley in the Upper Midwest region of the United States. The resistance of six-rowed malting cultivars like Morex has remained effective for over 40 years and is considered durable. Previous research on Steptoe/Morex (S/M), a 6×6-rowed doubled haploid (DH) population, showed that seedling resistance is controlled by a single gene (Rcs5) on chromosome 1(7H) and adult plant resistance by two quantitative trait loci (QTL): one of the major effect on chromosome 5(1H) explaining 62% of the phenotypic variance and a second of minor effect on chromosome 1(7H) explaining 9% of the phenotypic variance. To corroborate these results in a 2×6-rowed DH population, composite interval mapping (CIM) was performed on Harrington/Morex (H/M). As in the S/M population, a single major gene (presumably Rcs5) on chromosome 1(7H) conferred resistance at the seedling stage. However, at the adult plant stage, the results were markedly different as no chromosome 5(1H) effect whatsoever was detected. Instead, a QTL at or near Rcs5 on chromosome 1(7H) explained nearly all of the phenotypic variance (75%) for disease severity. To determine whether this result might be due to the genetic background of the two-rowed susceptible parent Harrington, we analyzed another DH population that included the same resistance donor (Morex) and another six-rowed susceptible cultivar Dicktoo (D/M). Three QTL conferred seedling resistance in the D/M population: one near Rcs5 on chromosome 1(7H) explaining 30%, a second near the centromere of chromosome 1(7H) explaining 9%, and a third on the short arm of chromosome 3(3H) explaining 19% of the phenotypic variation. As in the H/M population, no chromosome 5(1H) QTL was detected for adult plant resistance in the D/M population. Instead, three QTL on other chromosomes explained most of the variation: one on the short arm of chromosome 3(3H) explaining 36%, a second on the long arm of chromosome 3(3H) explaining 11%, and a third at or near Rcs5 on chromosome 1(7H) explaining 20% of the phenotypic variation. These data demonstrate the complexity of expression of spot blotch resistance in different populations and have important implications in breeding for durable resistance.     

Identification and mapping of net form of net blotch resistance in South African barley

Net form of net blotch (NFNB) caused by the fungus Pyrenophora teres f. teres is an economically important foliar disease of barley (Hordeum vulgare) in southern and eastern Africa. Little attention has been given to disease resistance breeding, and knowledge about the presence of NFNB resistance in breeding lines is limited. Deploying resistance into varieties used in this region is important for future control of the disease. We have identified NFNB disease resistance in existing South African breeders’ lines and have mapped the resistance in line UVC8. Six different trials, three conducted in South Africa and another three in Australia, were used to identify resistance QTL. A major QTL was identified on chromosome 6H having a LOD score of 40.5 and 55% of the phenotypic variance explained. Kompetitive Allele Specific PCR (KASP?) markers were designed for this QTL region. These and microsatellite markers can now be used to routinely select for NFNB resistance.     

Identification and mapping of a gene conferring resistance to the spot form of net blotch (Pyrenophora teres f maculata) in barley

 Spot form of net blotch (SFNB) (Pyrenophora teres f maculata) is an economically damaging foliar disease of barley in many of the world’s cereal growing areas. The development of SFNB-resistant cultivars may be accelerated through the use of molecular markers. A screen for SFNB resistance in 96 lines identified four new sources of resistance, including a feed variety, ‘Galleon’, for which a fully mapped doubled haploid population was available. Segregation data indicated SFNB resistance was conferred by a single gene in the ‘Galleon’בHaruna Nijo’ cross, positioned on the long arm of chromosome 7H. This gene is designated Rpt4 and is flanked by the RFLP loci Xpsr117(D) and Xcdo673 at distances of 6.9 cM and 25.9 cM, respectively. The marker Xpsr117(D) was validated using another population segregating for Rpt4, correctly predicting SFNB resistance with more than 90% accuracy. Received: 24 September 1998 / Accepted: 19 December 1998     

Identification of 50 K Illumina-chip SNPs associated with resistance to spot blotch in barley

Background

Spot blotch, caused by Cochliobolus sativus, is one of the most widespread and harmful diseases in barley. Identification of genetic loci associated with resistance to C. sativus is of importance for future marker-assisted selection. The goal of the current study was to identify loci conferring seedling resistance to two different pathotypes of C. sativus in the Siberian spring barley core collection.

Results

A total of 96 spring barley cultivars and lines were phenotyped at the seedling stage with two C. sativus isolates (Kr2 and Ch3). According to the Fetch-Steffenson rating scale 16%/17% of genotypes were resistant and 26%/30% were moderate-resistant to the Kr2/Ch3 isolates respectively. A total of 94 genotypes were analyzed with the barley 50 K Illumina Infinium iSELECT assay. From 44,040 SNPs, 40,703 were scorable, from which 39,140 were polymorphic. 27,319 SNPs passed filtering threshold and were used for association mapping. Data analysis by GLM revealed 48 and 41 SNPs for Kr2 and Ch3 isolates, respectively. After application of 5% Bonferroni multiple test correction, only 3 and 27 SNPs were identified, respectively. A total of three genomic regions were associated with the resistance. The region on chromosome 3H associated with Ch3-resistance was expanded between markers SCRI_RS_97417 and JHI-Hv50k-2016-158003 and included 11 SNPs, from which JHI-Hv50k-2016-157070, JHI-Hv50k-2016-156842 had the lowest p-values. These two SNPs were also significant in case of Kr2 isolate. The region on chromosome 2H included 16 loci (7 of them with the lowest p-values were tightly linked to BOPA2_12_11504). Three loci corresponding to this region had suggestive p-values in case of Kr2 tests, so the locus on chromosome 2H may also contribute to resistance to Kr2 isolate. The third region with significant p-value in case of Kr2 tests was identified on chromosome 1H at the locus JHI-Hv50k-2016-33568.

Conclusions

Three genomic regions associated with the resistance to one or both isolates of C. sativus were identified via screening of the Siberian spring barley core collection. Comparison of their location with QTLs revealed previously either with biparental mapping populations studies or with GWAS of distinct germplasm and other isolates, demonstrated that resistance to isolates Kr2 and Ch3 is conferred by known spot blotch resistance loci. Information on SNPs related can be used further for development of DNA-markers convenient for diagnostics of resistance-associated alleles in barley breeding programs.

     

Field screening for resistance to barley net blotch

Inoculation with barley net blotch from infested straw debris was compared with that from diseased plants after sowing infected grains. The straw debris had a high, uniform inoculation potential which gave an early, continuing infection and easily reproducible results that were effective for screening barley cultivars in the field for resistance against a natural population of the pathogen. Further, it minimises an eventual influence from other leaf pathogens coming from the surroundings. Irrigation was decisive for the success of the method - especially in the initial phase. Ten m separation with an immune crop was insufficient to completely prevent infection in the uninoculated plots. The tested 25 cvs were differentiated in six categories of resistant and susceptible on the basis of disease development and final level of attack. None of them was free of symptoms. The most resistant cvs kept a constant, low level of attack during the whole growing season, whereas the most susceptible cvs showed an early and rapidly increasing attack. Intermediate cvs were characterised with more or less slow increase of the attack. The size and proportion of the brown necrotic spots and the surrounding yellow halo varied greatly from one cultivar to the other. The grain yield reduction was due solely to an effect on the thousand grain weight which decreased linearly with the squared point score for net blotch. Further, the disease affected the quality of the grains as less nitrogen was transported from straw to grain in the severely diseased plants.     

Association mapping of resistance to Puccinia hordei in Australian barley breeding germplasm

Key message

“To find stable resistance using association mapping tools, QTL with major and minor effects on leaf rust reactions were identified in barley breeding lines by assessing seedlings and adult plants.”

Abstract

Three hundred and sixty (360) elite barley (Hordeum vulgare L.) breeding lines from the Northern Region Barley Breeding Program in Australia were genotyped with 3,244 polymorphic diversity arrays technology markers and the results used to map quantitative trait loci (QTL) conferring a reaction to leaf rust (Puccinia hordei Otth). The F_3:5 (Stage 2) lines were derived or sourced from different geographic origins or hubs of international barley breeding ventures representing two breeding cycles (2009 and 2011 trials) and were evaluated across eight environments for infection type at both seedling and adult plant stages. Association mapping was performed using mean scores for disease reaction, accounting for family effects using the eigenvalues from a matrix of genotype correlations. In this study, 15 QTL were detected; 5 QTL co-located with catalogued leaf rust resistance genes (Rph1, Rph3/19, Rph8/14/15, Rph20, Rph21), 6 QTL aligned with previously reported genomic regions and 4 QTL (3 on chromosome 1H and 1 on 7H) were novel. The adult plant resistance gene Rph20 was identified across the majority of environments and pathotypes. The QTL detected in this study offer opportunities for breeding for more durable resistance to leaf rust through pyramiding multiple genomic regions via marker-assisted selection.     

Genetics of seedling and adult plant resistance to net blotch (Pyrenophora teres f. teres) and spot blotch (Cochliobolus sativus) in barley

Net blotch (caused by Pyrenophora teres f. teres) and spot blotch (Cochliobolus sativus) are important foliar diseases of barley in the midwestern region of the USA. To determine the number and chromosomal location of Mendelian and quantitative trait loci (QTL) controlling resistance to these diseases, a doubled haploid population (Steptoe/Morex) was evaluated to the pathogens at the seedling stage in the greenhouse and at the adult plant stage in the field. Alleles at two or three unlinked loci were found to confer resistance to the net blotch pathogen at the seedling stage depending on how progeny exhibiting an intermediate infection response were classified. This result was corroborated in the quantitative analysis of the raw infection response data as 2 major QTL were identified on chromosomes 4 and 6M. A third QTL was also identified on chromosome 6P. Seven QTL were identified for net blotch resistance at the adult plant stage and mapped to chromosomes 1P, 2P, 3P, 3M, 4, 6P, and 7P. The 7 QTL collectively accounted for 67.6% of the phenotypic variance under a multiple QTL model. Resistance to the spot blotch pathogen was conferred by a single gene at the seedling stage. This gene was mapped to the distal region of chromosome 1P on the basis of both qualitative and quantitative data analyses. Two QTL were identified for spot blotch resistance at the adult plant stage: the largest QTL effect mapped to chromosome 5P and the other mapped to chromosome 1P near the seedling resistance locus. Together, the 2 QTL explained 70.1% of the phenotypic variance under a multiple QTL model. On the basis of the chromosomal locations of resistance alleles detected in this study, it should be feasible to combine high levels of resistance to both P. teres f. teres and C. sativus in barley cultivars.     

Association mapping of stem rust race TTKSK resistance in US barley breeding germplasm

Key message

Loci conferring resistance to the highly virulent African stem rust race TTKSK were identified in advanced barley breeding germplasm and positioned to chromosomes 5H and 7H using an association mapping approach.

Abstract

African races of the stem rust pathogen (Puccinia graminis f. sp. tritici) are a serious threat to barley production worldwide because of their wide virulence. To discover and characterize resistance to African stem rust race TTKSK in US barley breeding germplasm, over 3,000 lines/cultivars were assessed for resistance at the seedling stage in the greenhouse and also the adult plant stage in the field in Kenya. Only 12 (0.3 %) and 64 (2.1 %) lines exhibited a resistance level comparable to the resistant control at the seedling and adult plant stage, respectively. To map quantitative trait loci (QTL) for resistance to race TTKSK, an association mapping approach was conducted, utilizing 3,072 single nucleotide polymorphism (SNP) markers. At the seedling stage, two neighboring SNP markers (0.8 cM apart) on chromosome 7H (11_21491 and 12_30528) were found significantly associated with resistance. The most significant one found was 12_30528; thus, the resistance QTL was named Rpg-qtl-7H-12_30528. At the adult plant stage, two SNP markers on chromosome 5H (11_11355 and 12_31427) were found significantly associated with resistance. This resistance QTL was named Rpg-qtl-5H-11_11355 for the most significant marker identified. Adult plant resistance is of paramount importance for stem rust. The marker associated with Rpg-qtl-5H-11_11355 for adult plant resistance explained only a small portion of the phenotypic variation (0.02); however, this QTL reduced disease severity up to 55.0 % under low disease pressure and up to 21.1 % under heavy disease pressure. SNP marker 11_11355 will be valuable for marker-assisted selection of adult plant stem rust resistance in barley breeding.     

Application of BARE-1 retrotransposon markers to the mapping of a major resistance gene for net blotch in barley

Net blotch, which is caused by the fungus Pyrenophoral teres Drechs. f. teres Smedeg., presents a serious problem for barley production worldwide, and the identification and deployment of sources of resistance to it are key objectives for many breeders. Here, we report the identification of a major resistance gene, accounting for 65% of the response variation, in a cross between the resistant line C19819 and the susceptible cv. Rolfi. The resistance gene was mapped to chromosome 6H with the aid of two recently developed systems of retrotransposon-based molecular markers, REMAP and IRAP. A total of 239 BARE-1 and Sukkula retrotransposon markers were mapped in the cross, and the 30-cM segment containing the locus with significant resistance effect contained 26 of the markers. The type and local density of the markers should facilitate future map-based cloning of the resistance gene as well as manipulation of the resistance through backcross breeding.     

Mapping resistance to spot blotch in a CIMMYT synthetic-derived bread wheat

Spot blotch, caused by Cochliobolus sativus, is an important foliar disease of wheat in warmer wheat-growing regions leading to significant reductions in grain yield and quality. Although inoculum levels can be reduced by planting disease-free seed, treatment of plants with fungicides and crop rotation, genetic resistance is likely to be a robust, economical and environmentally friendly tool in the control of spot blotch. The spot blotch resistant synthetic derivative ‘SYN1’ was developed from a cross between two resistance sources, Mayoor and the primary synthetic bread wheat Tksn1081/Ae. squarrosa (222) that are likely to form an important component of resistance in many elite CIMMYT bread wheats. In order to map the loci underlying the resistance of ‘SYN1’, a doubled-haploid population produced from a cross between ‘SYN1’ and the susceptible CIMMYT-derived variety Ocoroni-86 was evaluated in artificially inoculated field nurseries in the 2010–2011 and 2011–2012 crop seasons at CIMMYT’s research station in Agua Fría, Mexico. Disease assessment was performed on three or four occasions and subsequently area under disease progress curve (AUDPC) calculated. Genotyping was with genotyping by sequencing and simple sequence repeat markers. Using inclusive composite interval mapping, three genomic regions were found to have a significant effect on spot blotch AUDPC in each of the 2 years of trials with phenotypic variation explained by QSb.cim-1B of 8.5 %, 17.6 % by QSb.cim-3B and 12.3 % by QSb.cim-5A. The quantitative trait loci (QTL) mapping results showed that the favorable alleles of QSb.cim-1B, QSb.cim-3B and QSb.cim-5A were derived from the synthetic-derived bread wheat SYN1. Genotypes of the parents of SYN1 indicated that the favorable alleles at these three QTLs were all inherited from Mayoor.     

Mapping quantitative trait loci associated with barley net blotch resistance

Net blotch of barley, caused by Pyrenophora teres Drechs., is an important foliar disease worldwide. Deployment of resistant cultivars is the most economic and eco-friendly control method. This report describes mapping of quantitative trait loci (QTL) associated with net blotch resistance in a doubled-haploid (DH) barley population using diversity arrays technology (DArT) markers. One hundred and fifty DH lines from the cross CDC Dolly (susceptible)/TR251 (resistant) were screened as seedlings in controlled environments with net-form net blotch (NFNB) isolates WRS858 and WRS1607 and spot-form net blotch (SFNB) isolate WRS857. The population was also screened at the adult-plant stage for NFNB resistance in the field in 2005 and 2006. A high-density genetic linkage map of 90 DH lines was constructed using 457 DArT and 11 SSR markers. A major NFNB seedling resistance QTL, designated QRpt6, was mapped to chromosome 6H for isolates WRS858 and WRS1607. QRpt6 was associated with adult-plant resistance in the 2005 and 2006 field trials. Additional QTL for NFNB seedling resistance to the more virulent isolate WRS858 were identified on chromosomes 2H, 4H, and 5H. A seedling resistance QTL (QRpts4) for the SFNB isolate WRS857 was detected on chromosome 4H as was a significant QTL (QRpt7) on chromosome 7H. Three QTL (QRpt6, QRpts4, QRpt7) were associated with resistance to both net blotch forms and lines with one or more of these demonstrated improved resistance. Simple sequence repeat (SSR) markers tightly linked to QRpt6 and QRpts4 were identified and validated in an unrelated barley population. The major 6H QTL, QRpt6, may provide adequate NFNB field resistance in western Canada and could be routinely selected for using molecular markers in a practical breeding program.     

Effect of chitosan and vanillin-modified chitosan on wheat resistance to spot blotch

The effect of chitosan- and vanillin-based immune modulators on the development of the phytopathogen Cochliobolus sativus (S. Ito & Kurib.) Drechsler ex Dastur, which induces dark-brown blotch (helminthosporiosis) in wheat, has been studied. It was shown that treatment with these substances led to a decreased injured area in leaves and an increase in the biotrophic period of pathogen development. It was found that vanillin-modified chitosan effectively provided wheat resistance to hemibiotrophic pathogen C. sativus. Changes in leaf peroxidase activity correlated with the manifestation of disease symptoms.     

Genome-wide association mapping of spot blotch resistance to three different pathotypes of <Emphasis Type="Italic">Cochliobolus sativus</Emphasis> in the USDA barley core collection

Spot blotch, caused by Cochliobolus sativus, is an economically important disease of barley. To identify genetic loci conferring resistance to three different pathotypes of C. sativus, a worldwide barley core collection (BCC) consisting of 1480 accessions from the USDA National Small Grains Collection were genotyped with the barley 9k Illumina Infinium iSELECT assay and phenotyped at the seedling stage with three C. sativus isolates ND85F (pathotype 1), ND90Pr (pathotype 2), and ND4008 (pathotype 7). Association mapping analysis was performed with the Whole_Panel containing 1480 barley accessions, as well as Two-rowed_Panel and Six-rowed_Panel consisting of 621 two-rowed and 857 six-rowed barley accessions, respectively. For resistance to isolate ND4008, one quantitative trait locus (QTL, QRcs-6H-P7) was detected in all three panels. Three other QTL (QRcs-1H-P7, QRcs-2H-P7, and QRcs-3H-P7) were detected in Whole_Panel, Six-rowed_Panel, and Two-rowed_Panel, respectively. For resistance to isolate ND90Pr, one QTL (QRcs-1H-P2) was identified in the Whole_Panel and the Two-rowed_Panel, and the other QTL (QRcs-6H-P2) was only identified in the Six-rowed_Panel. For resistance to isolate ND85F, three QTL (QRcs-1H-P1, QRcs-3H-P1, QRcs-7H-2-P1) were detected in all three panels, and one QTL (QRcs-7H-1-P1) was only detected in the Two-rowed_Panel. Among the ten QTL detected, four (QRcs-1H-P1, QRcs-3H-P1, QRcs-7H-2-P1, and QRcs-1H-P2) were mapped to chromosome regions containing previously identified QTL for spot blotch resistance, while six (QRcs-1H-P7, QRcs-2H-P7, QRcs-3H-P7, QRcs-6H-P7, QRcs-6H-P2, and QRcs-7H-1-P1) were novel. The SNP markers associated with the QTL identified in this study will be useful for breeding barley cultivars with resistance to multiple pathotypes of C. sativus.