Evidence of intralocus recombination at the <Emphasis Type="Italic">Glu-3</Emphasis> loci in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Key message

Recombination at the Glu-3 loci was identified, and strong genetic linkage was observed only between the amplicons representing i-type and s-type genes located, respectively, at the Glu-A3 and Glu-B3 loci.

Abstract

The low-molecular weight glutenin subunits (LMW-GSs) are one of the major components of wheat seed storage proteins and play a critical role in the determination of wheat end-use quality. The genes encoding this class of proteins are located at the orthologous Glu-3 loci (Glu-A3, Glu-B3, and Glu-D3). Due to the complexity of these chromosomal regions and the high sequence similarity between different LMW-GS genes, their organization and recombination characteristics are still incompletely understood. This study examined intralocus recombination at the Glu-3 loci in two recombinant inbred line (RIL) and one doubled haploid (DH) population, all segregating for the Glu-A3, Glu-B3, and Glu-D3 loci. The analysis was conducted using a gene marker system that consists of the amplification of the complete set of the LMW-GS genes and their visualization by capillary electrophoresis. Recombinant marker haplotypes were detected in all three populations with different recombination rates depending on the locus and the population. No recombination was observed between the amplicons representing i-type and s-type LMW-GS genes located, respectively, at the Glu-A3 and Glu-B3 loci, indicating tight linkage between these genes. Results of this study contribute to better understanding the genetic linkage and recombination between different LMW-GS genes, the structure of the Glu-3 loci, and the development of more specific molecular markers that better represent the genetic diversity of these loci. In this way, a more precise analysis of the contribution of various LMW-GSs to end-use quality of wheat may be achieved.

     

Allelic variations in <Emphasis Type="Italic">Glu-1</Emphasis> and <Emphasis Type="Italic">Glu-3</Emphasis> loci of historical and modern Iranian bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) cultivars

Proline and glutamine-rich wheat seed endosperm proteins are collectively referred to as prolamins. They are comprised of HMW-GSs, LMW-GSs and gliadins. HMW-GSs are major determinants of gluten elasticity and LMW-GSs considerably affect dough extensibility and maximum dough resistance. The inheritance of glutenin subunits follows Mendelian genetics with multiple alleles in each locus. Identification of the banding patterns of glutenin subunits could be used as an estimate for screening high quality wheat germplasm. Here, by means of a two-step 1D-SDS-PAGE procedure, we identified the allelic variations in high and low-molecular-weight glutenin subunits in 65 hexaploid wheat (Triticum aestivum L.) cultivars representing a historical trend in the cultivars introduced or released in Iran from the years 1940 to 1990. Distinct alleles 17 and 19 were detected for Glu-1 and Glu-3 loci, respectively. The allelic frequencies at the Glu-1 loci demonstrated unimodal distributions. At Glu-A1, Glu-B1 and Glu-D1, we found that the most frequent alleles were the null, 7 + 8, 2 + 12 alleles, respectively, in Iranian wheat cultivars. In contrast, Glu-3 loci showed bimodal or trimodal distributions. At Glu-A3, themost frequent alleles were c and e. At Glu-B3 the most frequent alleles were a, b and c. At Glu-D3 locus, the alleles b and a, were the most and the second most frequent alleles in Iranian wheat cultivars. This led to a significantly higher Nei coefficient of genetic variations in Glu-3 loci (0.756) as compared to Glu-1 loci (0.547). At Glu-3 loci, we observed relatively high quality alleles in Glu-A3 and Glu-D3 loci and low quality alleles at Glu-B3 locus.     

An integrative genetic linkage map of winter wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

We constructed a genetic linkage map based on a cross between two Swiss winter wheat (Triticum aestivum L.) varieties, Arina and Forno. Two-hundred and forty F₅ single-seed descent (SSD)-derived lines were analysed with 112 restriction fragment length polymorphism (RFLP) anonymous probes, 18 wheat cDNA clones coding for putative stress or defence-related proteins and 179 simple-sequence repeat (SSR) primer-pairs. The 309 markers revealed 396 segregating loci. Linkage analysis defined 27 linkage groups that could all be assigned to chromosomes or chromosome arms. The resulting genetic map comprises 380 loci and spans 3,086 cM with 1,131 cM for the A genome, 920 cM for the B genome and 1,036 cM for the D genome. Seventeen percent of the loci showed a significant (P < 0.05) deviation from a 1:1 ratio, most of them in favour of the Arina alleles. This map enabled the mapping of QTLs for resistance against several fungal diseases such as Stagonospora glume blotch, leaf rust and Fusarium head blight. It will also be very useful for wheat genetic mapping, as it combines RFLP and SSR markers that were previously located on separate maps. S. Paillard and T. Schnurbusch contributed equally to the work     

QTL mapping of flag leaf-related traits in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Key message

QTL controlling flag leaf length, flag leaf width, flag leaf area and flag leaf angle were mapped in wheat.

Abstract

This study aimed to advance our understanding of the genetic mechanisms underlying morphological traits of the flag leaves of wheat (Triticum aestivum L.). A recombinant inbred line (RIL) population derived from ND3331 and the Tibetan semi-wild wheat Zang1817 was used to identify quantitative trait loci (QTLs) controlling flag leaf length (FLL), flag leaf width (FLW), flag leaf area (FLA), and flag leaf angle (FLANG). Using an available simple sequence repeat genetic linkage map, 23 putative QTLs for FLL, FLW, FLA, and FLANG were detected on chromosomes 1B, 2B, 3A, 3D, 4B, 5A, 6B, 7B, and 7D. Individual QTL explained 4.3–68.52% of the phenotypic variance in different environments. Four QTLs for FLL, two for FLW, four for FLA, and five for FLANG were detected in at least two environments. Positive alleles of 17 QTLs for flag leaf-related traits originated from ND3331 and 6 originated from Zang1817. QTLs with pleiotropic effects or multiple linked QTL were also identified on chromosomes 1B, 4B, and 5A; these are potential target regions for fine-mapping and marker-assisted selection in wheat breeding programs.

     

A search for high-molecular-weight subunits of glutenin from <Emphasis Type="Italic">Triticum timopheevi</Emphasis> Zhuk. in the lines of common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L. <Emphasis Type="Italic">Triticum timopheevi</Emphasis> Zhuk.)

The study is a continuation of investigation of prolamins in brown rust-resistant introgressive lines of common wheat, produced with participation of Triticum timopheeevi Zhuk. [1]. Two wheat lines with a substitution of the Glu-1 loci of T. timopheevi were identified. Line 684 had high-molecular-weight glutenin subunits encoded by 1Ax, as well as by 1Ay gene, which was silent in commercial lines. It was demonstrated that line 684 could serve as a source of the Glu-A _t ¹ locus. Line 186 carried the Glu-B1/Glu-G1 substitution. Comparative analysis of storage proteins from the introgression lines of common wheat Triticum aestivum L. with those from parental forms demonstrated polymorphism among the lines, resulted from natural varietal polymorphism, and introgression of the Glu-3 and Gli-1 loci from the genome of T. timopheevi.     

The endophytic fungi from wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

In order to study the species composition of endophytes from wheat healthy plants in Buenos Aires Province (Argentina) and to determine their infection frequencies from leaves, stems, glumes and grains, wheat plants were collected from five cultivars at five growth stages from crop emergence to harvest. A total of 1,750 plant segments (leaves, stems, glumes and grains) were processed from the five wheat cultivars at five growth stages, and 722 isolates of endophytic fungi recovered were identified as 30 fungal genera. Alternaria alternata, Cladosporium herbarum, Epicoccum nigrum, Cryptococcus sp., Rhodotorula rubra, Penicillium sp. and Fusarium graminearum were the fungi that showed the highest colonization frequency (CF%) in all the tissues and organs analysed. The number of taxa isolated was greater in the leaves than those in the other organs analysed.     

Overexpression of <Emphasis Type="Italic">AtHDG11</Emphasis> enhanced drought tolerance in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Drought is one of the major abiotic stresses restricting the yield of wheat (Triticum aestivum L.). Breeding wheat varieties with drought tolerance is an effective and durable way to fight against drought. Here we reported introduction of AtHDG11 into wheat via Agrobacterium-mediated transformation and analyzed the morphological and physiological characteristics of T2 generation transgenic lines under drought stress. With drought treatment for 30 days, transgenic plants showed significantly improved drought tolerance. Compared with controls, the transgenic lines displayed lower stomatal density, lower water loss rate, more proline accumulation and increased activities of catalase and superoxide dismutase. Without irrigation after booting stage, the photosynthetic parameters, such as net photosynthesis rate, water use efficiency and efficiency of excitation energy, were increased in transgenic lines, while transpiration rate was decreased. Moreover, the kernel yield of transgenic lines was also improved under drought condition. Taken together, our data demonstrate that AtHDG11 has great potential in genetic improvement of drought tolerance of wheat.     

Quantitative trait loci for grain fructan concentration in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Fructans (fructo-oligosaccharides) are prebiotics that are thought to selectively promote the growth of colonic bifidobacteria, thereby improving human gut health. Fructans are present in the grain of wheat, a staple food crop. In the research reported here, we aimed to detect and map loci affecting grain fructan concentration in wheat using a doubled-haploid population derived from a cross between a high-fructan breeding line, Berkut, and a low-fructan cultivar, Krichauff. Fructan concentration was measured in grain samples grown at two locations in Australia and one in Kazakhstan. Fructan concentration varied widely within the population, ranging from 0.6 to 2.6% of grain dry weight, and was quite repeatable, with broad-sense heritability estimated as 0.71. With a linkage map of 528 molecular markers, quantitative trait loci (QTLs) were detected on chromosomes 2B, 3B, 5A, 6D and 7A. Of these, the QTLs on chromosomes 6D and 7A had the largest effects, explaining 17 and 27% of the total phenotypic variance, respectively, both with the favourable (high-fructan concentration) alleles contributed from Berkut. These chromosome regions had similar effects in another mapping population, Sokoll/Krichauff, with the favourable alleles contributed from Sokoll. It is concluded that grain fructan concentration of wheat can be improved by breeding and that molecular markers could be used to select effectively for favourable alleles in two regions of the wheat genome.     

QTL mapping for some grain traits in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Grain traits are important agronomic attributes with the market value as well as milling yield of bread wheat. In the present study, quantitative trait loci (QTL) regulating grain traits in wheat were identified. Data for grain area size (GAS), grain width (GWid), factor form density (FFD), grain length-width ratio (GLWR), thousand grain weight (TGW), grain perimeter length (GPL) and grain length (GL) were recorded on a recombinant inbred line derived from the cross of NW1014?×?HUW468 at Meerut and Varanasi locations. A linkage map of 55 simple sequence repeat markers for 8 wheat chromosomes was used for QTL analysis by Composite interval mapping. Eighteen QTLs distributed on 8 chromosomes were identified for seven grain traits. Of these, five QTLs for GLWR were found on chromosomes 1A, 6A, 2B, and 7B, three QTLs for GPL were located on chromosomes 4A, 5A and 7B and three QTLs for GAS were mapped on 5D and 7D. Two QTLs were identified on chromosomes 4A and 5A for GL and two QTLs for GWid were identified on chromosomes 7D and 6A. Similarly, two QTLs for FFD were found on chromosomes 1A and 5D. A solitary QTL for TGW was identified on chromosome 2B. For several traits, QTLs were also co-localized on chromosomes 2B, 4A, 5A, 6A, 5D, 7B and 7D. The QTLs detected in the present study may be validated for specific crosses and then used for marker-assisted selection to improve grain quality in bread wheat.     

Molecular mapping of powdery mildew resistance gene <Emphasis Type="Italic">PmHNK</Emphasis> in winter wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) cultivar Zhoumai 22

The Chinese winter wheat cultivar Zhoumai 22 is highly resistant to powdery mildew. The objectives of this study were to map a powdery mildew resistance gene in Zhoumai 22 using molecular markers and investigate its allelism with Pm13. A total of 278 F₂ and 30 BC₁ plants, and 143 F₃ lines derived from the cross between resistant cultivar Zhoumai 22 and susceptible cultivar Chinese Spring were used for resistance gene tagging. The 137 F₂ plants from the cross Zhoumai 22/2761-5 (Pm13) were employed for the allelic test of the resistance genes. Two hundred and ten simple sequence repeat (SSR) markers were used to test the two parents, and resistant and susceptible bulks. Subsequently, seven polymorphic markers were used for genotyping the F₂ and F₃ populations. The results indicated that the powdery mildew resistance in Zhoumai 22 was conferred by a single dominant gene, designated PmHNK tentatively, flanked by seven SSR markers Xgwm299, Xgwm108, Xbarc77, Xbarc84, Xwmc326, Xwmc291 and Xwmc687 on chromosome 3BL. The resistance gene was closely linked to Xwmc291 and Xgwm108, with genetic distances of 3.8 and 10.3 cM, respectively, and located on the chromosome bin 3BL-7-0.63-1.0 in the test with a set of deletion lines. Seedling tests with seven isolates of Blumeria graminis f. sp. tritici (Bgt) and allellic test indicated that PmHNK is different from Pm13, and Pm41 seems also to be different from PmHNK due to its origin from T. dicoccoides and molecular evidence. These results indicate that PmHNK is likely to be a novel powdery mildew resistance gene in wheat.     

Assessing genetic diversity of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) germplasm using microsatellite markers

A set of 24 wheat microsatellite markers, representing at least one marker from each chromosome, was used for the assessment of genetic diversity in 998 accessions of hexaploid bread wheat (Triticum aestivum L.) which originated from 68 countries of five continents. A total of 470 alleles were detected with an average allele number of 18.1 per locus. The highest number of alleles per locus was detected in the B genome with 19.9, compared to 17.4 and 16.5 for genomes A and D, respectively. The lowest allele number per locus among the seven homoeologous groups was observed in group 4. Greater genetic variation exists in the non-centromeric regions than in the centromeric regions of chromosomes. Allele numbers increased with the repeat number of the microsatellites used and their relative distance from the centromere, and was not dependent on the motif of microsatellites. Gene diversity was correlated with the number of alleles. Gene diversity according to Nei for the 26 microsatellite loci varied from 0.43 to 0.94 with an average of 0.77, and was 0.78, 0.81 and 0.73 for three genomes A, B and D, respectively. Alleles for each locus were present in regular two or three base-pair steps, indicating that the genetic variation during the wheat evolution occurred step by step in a continuous manner. In most cases, allele frequencies showed a normal distribution. Comparative analysis of microsatellite diversity among the eight geographical regions revealed that the accessions from the Near East and the Middle East exhibited more genetic diversity than those from the other regions. Greater diversity was found in Southeast Europe than in North and Southwest Europe. The present study also indicates that microsatellite markers permit the fast and high throughput fingerprinting of large numbers of accessions from a germplasm collection in order to assess genetic diversity.     

Assessment of genetic diversity among Syrian durum (<Emphasis Type="Italic">Triticum</Emphasis> ssp. <Emphasis Type="Italic">durum</Emphasis>) and bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) using SSR markers

Genetic diversity among 49 wheat varieties (37 durum and 12 bread wheat) was assayed using 32 microsatellites representing 34 loci covering almost the whole wheat genome. The polymorphic information content (PIC) across the tested loci ranged from 0 to 0.88 with average values of 0.57 and 0.65 for durum and bread wheat respectively. B-genome had the highest mean number of alleles (10.91) followed by A genome (8.3) whereas D genome had the lowest number (4.73). The correlation between PIC and allele number was significant in all genome groups accounting for 0.87, 074 and 0.84 for A, B and D genomes respectively, and over all genomes, the correlation was higher in tetraploid (0.8) than in hexaploid wheat varieties (0.5). The cluster analysis discriminated all varieties and clearly divided the two ploidy levels into two separate clusters that reflect the differences in genetic diversity within each cluster. This study demonstrates that microsatellites markers have unique advantages compared to other molecular and biochemical fingerprinting techniques in revealing the genetic diversity in Syrian wheat varieties that is crucial for wheat improvement.     

Structure and expression of the <Emphasis Type="Italic">TaGW7</Emphasis> in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

OsGW7 (also known as OsGL7) is homologous to the Arabidopsis thaliana gene that encodes LONGIFOLIA protein, which regulates cell elongation, and is involved in regulating grain length in rice. However, our knowledge on its ortholog in wheat, TaGW7, is limited. In this study, we identified and mapped TaGW7 in wheat, characterized its nucleotide and protein structures, predicted the cis-elements of its promoter, and analysed its expression patterns. The GW7 orthologs in barley (HvGW7), rice (OsGW7), and Brachypodium distachyon (BdGW7) were also identified for comparative analyses. TaGW7 mapped onto the short arms of group 2 chromosomes (2AS, 2BS, and 2DS). Multiple alignments indicated GW7 possesses five exons and four introns in all but two of the species analysed. An exon–intron junction composed of introns 3–4 and exons 4–5 was highly conserved. GW7 has a conserved domain (DUF 4378) and two neighbouring low complexity regions. GW7 was mainly expressed in wheat spikes and stems, in barley seedling crowns, and in rice anthers and embryo-sacs during early development. Drought and heat significantly increased and decreased GW7 expression in wheat, respectively. In barley, GW7 was significantly down-regulated in paleae and awns but up-regulated in seeds under drought treatment and down-regulated under Fusarium and stem rust inoculation. In rice, OsGW7 expression differed significantly under drought treatments. Collectively, these results provide insights into GW7 structure and expression in wheat, barley and rice. The GW7 sequence structure and expression data are the foundation for manipulating GW7 and uncovering its roles in plants.     

Anther culture as an effective tool in winter wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) breeding

The aim of this study was to determine the effect of genotype and induction medium in anther culture of wheat (Triticum aestivum L.). Ten F1 winter wheat genotypes were tested in anther culture (AC) to compare the two most frequently applied induction media (W14mf and P4mf). Androgenesis was induced during the treatment of each tested genotypes and green plants were produced from them using both media. Based on statistical analysis, the genotypes significantly influenced (at the 0.001 probability level) the efficiency of AC (embryo-like structures (ELS), albinos, green plantlets and transplanted plantlets) and the media also had a significant effect on the number of ELS and albino plantlets. Both media can be used for AC in wheat doubled haploid (DH) plant production. The production of ELS and green plantlets was higher in P4mf medium (48.84 ELS/100 anthers, 4.82 green plantlets/100 anthers) than in W14mf medium (28.14 ELS/100 anthers, 4.59 green plantlets/100 anthers). However, the green plant regeneration efficiency of the microspore-derived structures was 16.9% when using W14mf medium, while this value was 9.6% in the case of ELS induced with P4mf medium. The application of W14mf medium thus proved to be time- and labour-saving medium in the large-scale production of DH wheat plants. In our experiments, 267 DH plants were produced for our winter wheat breeding program. The spontaneous rediploidization rate was 32.72%.     

Identification of SNPs and development of functional markers for LMW-GS genes at <Emphasis Type="Italic">Glu-D3</Emphasis> and <Emphasis Type="Italic">Glu-B3</Emphasis> loci in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Low-molecular-weight glutenin subunits (LMW-GS) have great effect on wheat processing quality, but were numerous and difficult to dissect by SDS-PAGE. The development of functional markers may be the most effective way for a clear discrimination of different LMW-GS genes. In the present study, three different approaches were used to identify SNPs of different genes at Glu-D3 and Glu-B3 loci in bread wheat for the development of six STS markers (3 for Glu-D3 and 3 for Glu-B3 genes) that were validated with distinguished wheat cultivars. Firstly, seven LMW-GS gene sequences ( AY585350, AY585354, AY585355, AY585356, AY585349, AY585351 and AY585353 ) from Aegilops tauschii, the diploid donor of the D-genome of bread wheat, were chosen to design seven pairs of AS-PCR primers for Glu-D3 genes. By amplifying the corresponding genes from five bread wheat cultivars with different Glu-D3 alleles (a, b, c, d and e) and Ae. tauschii, a primer set, S13F2/S13R1, specific to the gene AY585356, was found to be positive to cultivars with alleles Glu-D3c and d. Nevertheless, the other five pairs of primers designed from AY585350, AY585349, AY585353, AY585354 and AY585355, respectively, did not produce specific PCR products to the cultivars tested. Secondly, all the PCR products from the five primer sets without specific characteristics were sequenced and an SNP from the gene AY585350 was detected in the cultivar Hartog, which resulted in the second STS marker S1F1/S1R3 specific to the allelic variant of AY585350. Thirdly, three Glu-D3 sequences (AB062851, AB062865 and AB062872) and three Glu-B3 sequences (AB062852, AB062853 and AB062860) defined by Ikeda et al. (2002) were chosen to query wheat EST and NR databases, and DNA markers were developed based on the putative SNPs among the sequences. Using this approach, four STS markers were developed and validated with 16-19 bread wheat cultivars. The primer set T1F4/T1R1 was also a Glu-D3 gene-specific marker for AB062872, while T2F2/T2R2, T5F3/T5R1 and T13F4/T13R3 were all Glu-B3 gene specific markers for AB062852, BF293671 and AY831800, respectively. The chromosomal locations of the six markers were verified by amplifying the genomic DNA of Ae. tauschii (DD), T. monococcum (AA) and T. turgidum (AABB) entries, as well as Chinese Spring and its group 1 chromosome nulli-tetrasomic lines. The results are useful to discriminate the corresponding Glu-D3 and Glu-B3 genes in wheat breeding programs.     

Functional gene markers for polyphenol oxidase locus in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Higher polyphenol oxidase (PPO) activity in wheat kernels and flour has been implicated in the time dependent darkening of various end-products. Previous study conducted on a bread wheat (Triticum aestivum L.) doubled haploid (DH) mapping population derived from Chara (medium-high PPO) and WW2449 (low PPO) identified a major QTL for PPO activity located on the long arm of chromosome 2A. Physical mapping of SSR markers accounting for up to 84% of phenotypic variation for PPO activities suggests that the candidate PPO locus is localised in the deletion bin delimited by 2AL 0.77–0.85. In order to develop functional gene markers, nine wheat ESTs mapped to this deletion bin and partial PPO reference genes were explored for their sequence identities and linkage with PPO locus in a mapping population. In the present study, two markers: one SNP and one CAPS based upon BQ161439 sequence variation between the parents were identified which exhibited a tight linkage (0–0.6 cM) with the PPO loci designated as XTc1 and XPPO- _LDOPA. We also mapped the reference PPO gene (GenBank AY526268) characterised from developing kernels of wheat, on the long arm of chromosome 2A which exhibited a complete linkage with XPPO- _L DOPA locus. Results suggest that PPO variation displayed in the DH population from Chara/WW2449 is due to the same reference PPO gene. Allelic homoplasy of tightly linked markers, indicated that these markers are ‘diagnostic’ for the selection of low PPO gene in a range of germplasm being used in different Australian breeding programs. Identification and validation of ‘functional gene markers’ would facilitate in enhancing the selection efficiency for low PPO activity in wheat breeding programs.     

Genome-wide association mapping of resistance to eyespot disease (<Emphasis Type="Italic">Pseudocercosporella herpotrichoides</Emphasis>) in European winter wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) and fine-mapping of <Emphasis Type="Italic">Pch1</Emphasis>

Key message

Genotypes with recombination events in the Triticum ventricosum introgression on chromosome 7D allowed to fine-map resistance gene Pch1, the main source of eyespot resistance in European winter wheat cultivars.

Abstract

Eyespot (also called Strawbreaker) is a common and serious fungal disease of winter wheat caused by the necrotrophic fungi Oculimacula yallundae and Oculimacula acuformis (former name Pseudocercosporella herpotrichoides). A genome-wide association study (GWAS) for eyespot was performed with 732 microsatellite markers (SSR) and 7761 mapped SNP markers derived from the 90 K iSELECT wheat array using a panel of 168 European winter wheat varieties as well as three spring wheat varieties and phenotypic evaluation of eyespot in field tests in three environments. Best linear unbiased estimations (BLUEs) were calculated across all trials and ranged from 1.20 (most resistant) to 5.73 (most susceptible) with an average value of 4.24 and a heritability of H ² = 0.91. A total of 108 SSR and 235 SNP marker–trait associations (MTAs) were identified by considering associations with a ?log₁₀ (P value) ≥3.0. Significant MTAs for eyespot-score BLUEs were found on chromosomes 1D, 2A, 2D, 3D, 5A, 5D, 6A, 7A and 7D for the SSR markers and chromosomes 1B, 2A, 2B, 2D, 3B and 7D for the SNP markers. For 18 varieties (10.5%), a highly resistant phenotype was detected that was linked to the presence of the resistance gene Pch1 on chromosome 7D. The identification of genotypes with recombination events in the introgressed genomic segment from Triticum ventricosum harboring the Pch1 resistance gene on chromosome 7DL allowed the fine-mapping of this gene using additional SNP markers and a potential candidate gene Traes_7DL_973A33763 coding for a CC-NBS-LRR class protein was identified.