Barley Breeding Lines Research Articles

The use of parametric and non-parametric measures for selecting stable and adapted barley lines

ABSTRACTThis research was carried out to estimate yield stability of 18 barley breeding lines using different parametric and non-parametric statistics across 15 environments during 2012–2015 growing seasons. The results of combined analysis of variance (ANOVA) and additive main effect and multiplicative interaction (AMMI) analysis showed that environments (E), genotypes (G), GE interaction, as well as the first four interaction principal component axes were highly significant, suggesting that the lines interacted differentially with environments, so further general adaptability and stability analysis across environments should be followed before being introduced for cultivation. Based on correlation coefficient and principal components analysis (PCA), most of the non-parametric statistics were significantly inter-correlated with parametric statistics, hence seem to be suitable alternatives to complement parametric statistics. Furthermore, according to the static and dynamic concepts of stability, the results revealed that stability statistics can be clustered into three groups. The overall stability analysis following different stability methods concluded that four lines (G5, G7, G17 and G20) were highly stable for grain yield in rain-fed conditions of subtropical regions of Iran. Thus, these lines can be recognized as the most stable lines for cultivation in diverse environments of semi-warm regions of Iran.

Physiological and molecular characterization of Kenyan barley (Hordeum vulgare L.) seedlings for salinity and drought tolerance

Genotype variation in selected Kenyan barley breeding lines was determined by differential profiles of seed hordein proteins using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Consequently, a phylogenetic relationship derived from unweighted pair group method with arithmetic mean Jaccard clustering matrix was generated based on absence or presence of hordein bands. In parallel, physiological and molecular responses to abiotic stresses were evaluated in seedlings. For physiological assays seedlings were exposed to 0, 300, 600 mM NaCl. Variation in physiological parameters including ionic conductance, lipid peroxidation, chlorophyll content, accumulation of proline, glycine betaine, sucrose was determined. Response to abiotic stress was found to be genotype dependent and varied with the stress magnitude. A low ionic conductance, lipid peroxidation and increased proline, sucrose, GB, chlorophyll were associated with stress tolerance. The lines Nguzo, MN-24 and MN-8 were tolerant while Karne, and Sabini were susceptible to abiotic stress. Transcript analysis of selected members of the dehydrin (Dhn) superfamily (LEA II) genes in root and shoot tissue were evaluated. Expression of Dhn genes was found to be genotype dependent, tissue specific and was affected by type and duration of stress. Dehydrin Dhn1 and Dhn9 genes were exclusively dehydration responsive while Dhn3, Dhn4 and Dhn7 were induced by both dehydration and increased salt treatments. Immunoblot analysis using polyclonal anti-sera detecting the K segment consensus peptide TGEKKGIMDKIKEKLPGQH showed a direct correlation between transcript level and accumulation of corresponding Dhn proteins in response to stress. These screening assays may be potential selection markers to aid rapid screening in breeding programs.

Impact of cereal diseases on the qualitative traits of spring barley breeding lines

Summary The differences between individual breeding lines of spring barley and a control variety were tested in terms of several measured (continuous) and qualitative traits. The impact of the qualitative traits (diseases) on the quantitative traits, especially yield, was assessed on the basis of the significance of differences for both qualitative traits and yield. Depending on the type of trait, either a logistic model or analysis of variance was used as a statistical tool. The statistically significant differences between some breeding lines and the control variety were shown. It was observed that in fodder barley both infection by mildew and lodging influenced yield. The results of analyses obtained in the so-called pre-preliminary trials and preliminary trials were different. This fact confirmed the necessity of repeating trials over several years.

Genomic prediction ability for yield-related traits in German winter barley elite material.

Genomic prediction was evaluated in German winter barley breeding lines. In this material, prediction ability is strongly influenced by population structure and main determinant of prediction ability is the close genetic relatedness of the breeding material. To ensure breeding progress under changing environmental conditions the implementation and evaluation of new breeding methods is of crucial importance. Modern breeding approaches like genomic selection may significantly accelerate breeding progress. We assessed the potential of genomic prediction in a training population of 750 genotypes, consisting of multiple six-rowed winter barley (Hordeum vulgare L.) elite material families and old cultivars, which reflect the breeding history of barley in Germany. Crosses of parents selected from the training set were used to create a set of double-haploid families consisting of 750 genotypes. Those were used to confirm prediction ability estimates based on a cross-validation with the training set material using 11 different genomic prediction models. Population structure was inferred with dimensionality reduction methods like discriminant analysis of principle components and the influence of population structure on prediction ability was investigated. In addition to the size of the training set, marker density is of crucial importance for genomic prediction. We used genome-wide linkage disequilibrium and persistence of linkage phase as indicators to estimate that 11,203 evenly spaced markers are required to capture all QTL effects. Although a 9k SNP array does not contain a sufficient number of polymorphic markers for long-term genomic selection, we obtained fairly high prediction accuracies ranging from 0.31 to 0.71 for the traits earing, hectoliter weight, spikes per square meter, thousand kernel weight and yield and show that they result from the close genetic relatedness of the material. Our work contributes to designing long-term genetic prediction programs for barley breeding.

Graphical analysis of adaptability of spring barley breeding lines in the Central Forest-Steppe zone of Ukraine

Purpose. To define spring barley breeding lines with an optimal combination of yielding capacity and stability under different weather conditions in the Central Forest-Steppe zone of Ukraine.Methods. Field studies, ANOVA, AMMI, GGE biplot analysis.Results. Hydrothermal regime during interphase periods of spring barley vegetation under conditions of The V. M. Remeslo Myronivka Institute of Wheat of NAAS in 2012–2014 was characterized by significant variability, that facilitated detailed evaluation of the lines for productivity, stability, and resistance to abiotic and biotic factors. In the performance of an experiment, the highest average yielding capacity (5.87 t/ha) was noted in 2012, the lowest one (3.50 t/ha) was in 2013. As for these years, average yield of 4.63 t/ha was obtained in 2014. By applying AMMI and GGE biplot analysis, significant differences in response of the studied lines to variability of weather conditions was revealed. Using AMMI model, additive components of the main effects of the breeding lines and years of testing as well as multiplicative components of their interaction were characterized. GGE biplot genotypes ranking in relation to a hypothetical “ideal” genotype showed an absolute advantage of breeding line ‘Nutans 4540’ for yielding capacity and stability. In addition, breeding lines ‘Nutans 4241’ and ‘Nutans 4120’ were close to ideatype. Selected breeding lines were characterized by resistance and moderate resistance to leaf diseases and lodging.Conclusions. Use of AMMI and GGE biplot analysis to evaluate breeding lines at the final stages of breeding process allows to describe them thoroughly and graphically as well as differentiate them not only for average yielding capacity but also for their interaction with changing conditions during the years of testing. Breeding lines ‘Nutans 4540’, ‘Nutans 4241’, and ‘Nutans 4120’ to be identified for the stability of yielding capacity display in combination with other agronomic characters were transferred to the State variety testing as new spring barley varieties ‘MIP Myrnyi’, ‘MIP Saliut’, and ‘MIP Sotnyk’ respectively.

Inducing sporulation of Drechslera graminea

Barley stripe, caused by the fungus Pyrenophora graminea, is a single-cycle, seedborne disease. P. graminea is rarely observed in the nature, but its imperfect state, Drechslera graminea, occurs in all infected barley leaves. D. graminea produces conidia, which are in clusters of three to five. The fungus can also produce pycnidia, but it is rare in nature. Although barley stripe is effectively managed by seed-treatment with fungicides, losses to this disease still incurs wherever proper seed treatment is not practiced. D. graminea does not sporulate on commonly used artificial culture media. Therefore, production of spores to be used for screening accessions and breeding lines of barley for resistance to barley strip was not possible. A simple method was developed to induce sporulation in D. graminea. Thirty-six isolates of D. graminea, gathered from Canada, Germany, Montana and Syria, were cultured, developed vigorous colonies and produced abundant conidia. Sporulation of the fungus was induced using straw extract from the barley cultivars arta, bowman, bracken, clark, gallatin, and salmas. There were significant differences in sporulation among isolates from different areas as well as among isolates originating from the same barley field. Incubating the culture plates at 160C under fluorescent light (12 h light/12 h dark) for 5 d following incubation under near ultraviolet (NUV) light for 7 d resulted in 40% higher conidia production. Extract of seed, green straw or green leaves of barley as well as extract of mature wheat straw did not induce sporulation in D. graminea in culture. Twenty-one of the 36 isolates produced pycnidia following the 7-day incubation under NUV light. Five of 25 isolates grown on V8juice agar failed to sporulate. Germination of conidia of 12 isolates ranged from 72 to 99%.

Evaluation of spring barley breeding lines in a two-year multi-location experiment using some statistical methods

Abstract In breeding experiments conducted prior to tests connected with the registration of new breeding lines of crops, pre-preliminary and preliminary trials are carried out. In this study a comparison was made among some models of analysis of variance, in relation to the selection of new breeding lines of spring barley (Hordeum vulgare L.). The aim is to determine whether the choice of model of analysis of variance may influence the choice of tested breeding lines. The trait considered was the yield in two years of trials. A more comprehensive analysis of variance model was found to be superior. It was also found that the results of analyses performed using average measurements for lines significantly differ from those obtained on the basis of all measurements. It was concluded that the type of ANOVA model used may have an impact on inferences about breeding lines. Moreover, a lack of stability in the yields of tested lines was revealed, implying the necessity of several years of trials.

Production of Ethanol From Newly Developed and Improved Winter Barley Cultivars.

Winter barley has attracted strong interest as a potential feedstock for fuel ethanol production in regions with mild winter climate such as the mid-Atlantic and northeastern USA. Ten recently developed and improved winter barley cultivars and breeding lines including five hulled and five hull-less lines were experimentally evaluated for potential ethanol production. The five hulled barley lines included three released cultivars (Thoroughbred, Atlantic, and Secretariat) and two breeding lines (VA09B-34 and VA11B-4). The five hull-less lines also included three released cultivars (Eve, Dan, and Amaze 10) and two breeding lines (VA08H-65 and VA13H-34). On the average, the hull-less barley cultivars produced more ethanol per unit mass because of their higher starch and β-glucan contents. However, since the hulled barley cultivars had higher agronomic yield, the potential ethanol production per acre of land for the two types were approximately equal. Among the ten cultivars tested, the hull-less cultivar Amaze 10 was the best one for ethanol production. The ethanol yield values obtained for this cultivar were 2.61gal per bushel and 292gal per acre.

Genome-Wide Association Study of Spot Form of Net Blotch Resistance in the Upper Midwest Barley Breeding Programs.

Pyrenophora teres f. maculata, the causal agent of spot form of net blotch (SFNB), is an emerging pathogen of barley in the United States and Australia. Compared with net form of net blotch (NFNB), less is known in the U.S. Upper Midwest barley breeding programs about host resistance and quantitative trait loci (QTL) associated with SFNB in breeding lines. The main objective of this study was to identify QTL associated with SFNB resistance in the Upper Midwest two-rowed and six-rowed barley breeding programs using a genome-wide association study approach. A total of 376 breeding lines of barley were evaluated for SFNB resistance at the seedling stage in the greenhouse in Fargo in 2009. The lines were genotyped with 3,072 single nucleotide polymorphism (SNP) markers. Phenotypic evaluation showed a wide range of variability among populations from the four breeding programs and the two barley-row types. The two-rowed barley lines were more susceptible to SFNB than the six-rowed lines. Continuous distributions of SFNB severity indicate the quantitative nature of SFNB resistance. The mixed linear model (MLM) analysis, which included both population structure and kinship matrices, was used to identify significant SNP-SFNB associations. Principal component analysis was used to control false marker-trait association. The linkage disequilibrium (LD) estimates varied among chromosomes (10 to 20 cM). The MLM analysis identified 10 potential QTL in barley: SFNB-2H-8-10, SFNB-2H-38.03, SFNB-3H-58.64, SFNB-3H-78.53, SFNB-3H-91.88, SFNB-3H-117.1, SFNB-5H-155.3, SFNB-6H-5.4, SFNB-6H-33.74, and SFNB-7H-34.82. Among them, four QTL (SFNB-2H-8-10, SFNB-2H-38.03 SFNB-3H-78.53, and SFNB-3H-117.1) have not previously been published. Identification of SFNB resistant lines and QTL associated with SFNB resistance in this study will be useful in the development of barley genotypes with better SFNB resistance.

Quantification of trace elements Fe, Zn, Mn, Se in hull-less barley grain

Aim. To explore the content of trace elements (TE), most valuable for human health – iron, zinc, manganese and selenium – in cultivars and breeding lines of hull-less barley, and to check the impact of abiotic environ- mental factors on TE accumulation in the grain of Achilles cultivar. Methods. Trace elements content was measured using ICP-MS Agilent 7700x. Results. The content of vital TE was determined in 26 samples of hull-less barley grain. The increased concentration of TE was observed in the samples with brown, blue and black caryopsis. The absence of dependence between abiotic environmental factors and TE accumulation was demonstrated using Achilles cultivar, presented by six different repeats. The correlation between the content of protein and that of iron in grain was established. Conclusions. White grain barley cultivars and lines are infe- rior in the content of Fe, Zn, Mn, and Se comparing to genotypes with brown, blue or black grain. The presence or absence of a fi lm on a hull-less barley grain has almost no impact on the amount of TE, which, as expected, are located in the aleurone layer and the germ of caryopsis. It was proven that the content of Fe, Zn, Mn in the Achilles grain almost did not change regardless of abiotic environmental factors. A high correlation, r = 0.87, Р > 0.05−0.001, was found between the content of protein and Fe in grain.

The Effects of Both Recent and Long-Term Selection and Genetic Drift Are Readily Evident in North American Barley Breeding Populations.

Barley was introduced to North America ∼400 yr ago but adaptation to modern production environments is more recent. Comparisons of allele frequencies among growth habits and spike (inflorescence) types in North America indicate that significant genetic differentiation has accumulated in a relatively short evolutionary time span. Allele frequency differentiation is greatest among barley with two-row vs. six-row spikes, followed by spring vs. winter growth habit. Large changes in allele frequency among breeding programs suggest a major contribution of genetic drift and linked selection on genetic variation. Despite this, comparisons of 3613 modern North American cultivated barley breeding lines that differ for spike-type and growth habit permit the discovery of 142 single nucleotide polymorphism (SNP) outliers putatively linked to targets of selection. For example, SNPs within the Cbf4, Ppd-H1, and Vrn-H1 loci, which have previously been associated with agronomically adaptive phenotypes, are identified as outliers. Analysis of extended haplotype sharing identifies genomic regions shared within and among breeding populations, suggestive of a number of genomic regions subject to recent selection. Finally, we are able to identify recent bouts of gene flow between breeding populations that could point to the sharing of agronomically adaptive variation. These results are supported by pedigrees and breeders’ understanding of germplasm sharing.

The constitutive expression and induction of three β-1,3-glucanases by bird cherry-oat aphid in relation to aphid resistance in 15 barley breeding lines

In this study, 15 closely related barley genotypes were analyzed for the abundance of three β-1,3-glucanase transcripts immediately before and during infestation by the bird cherry-oat aphid (Rhopa ...

Survey of Barley yellow dwarf virus incidence in winter cereal crops, and assessment of wheat and barley resistance to the virus

A survey of Barley yellow dwarf virus (BYDV) incidence in cereal crops in the Czech Republic over 4 years showed, on average, 13.3% BYDV-positive, randomly tested wheat and barley samples. The cultivated wheat and barley cultivars had different levels of susceptibility to BYDV infection. Field trials were performed with different barley and wheat breeding lines and cultivars, and resistance traits were evaluated after artificial inculcation by the viruliferous aphid vector Rhopalosiphum padi L. with BYDV-PAV. Our results showed high variability of visual symptom score (VSS) and reduction in grain weight per spike (GWS-R) in trials within the tested lines and cultivars. The barley line (WBON 96-123) and cultivars (Wysor, Travira) that contained RYd2 differed significantly from other cultivars in VSS. Line WBON 96-123 and cvv. Wysor and Yatzi showed the lowest GWS-R. Wheat line PSR 3628 and cvv. Altigo, Elan, Sparta, Aladin and Hewit showed significant difference from other cultivars in VSS. PSR 3628, Sparta, and Elan showed the lowest GWS-R. Similar results were obtained from BYDV titre analysis by RT-qPCR corresponding to the VSS and GWS-R traits. A low virus titre corresponded to low VSS and GWS-R. Hence, our results suggest that laborious and time-consuming GWS-R analysis could be replaced in some cases by qPCR-based BYDV titre analysis and, together with VSS evaluation, could enhance the efficiency of resistance assessment.

Evaluation of Canadian barley breeding lines for Fusarium head blight resistance

He, X., Osman, M., Helm, J., Capettini, F. and Singh, P. K. 2015. Evaluation of Canadian barley breeding lines for Fusarium head blight resistance. Can. J. Plant Sci. 95: 923–929. Fusarium head blight (FHB) is a major challenge to the successful production of barley in Canada, as well as for end-users such as the malting and brewing industries. Due to the quantitative inheritance of FHB resistance, continuous effort is required to identify breeding lines with improved FHB resistance and incorporate them into crossing schemes to enhance FHB resistance. In the present study, 402 advanced breeding lines from Alberta, Canada, were evaluated in the FHB screening nursery at CIMMYT, Mexico. In 2011 and 2012, FHB incidence was measured on a scale of 1 to 4 to eliminate the most susceptible lines. In 2013 and 2014, 181 lines with the lowest disease scores in the previous 2 yr were tested in replicated experiments for field FHB index, Fusarium-damaged kernels, and deoxynivalenol content. Agronomic and morphological traits, specifically days to heading, plant height, and row and hull types were also evaluated in relations to FHB parameters. Correlation coefficients among the three FHB parameters in both 2013 and 2014 were all significant at P<0.0001, ranging from 0.36 to 0.63. Additional correlation analysis showed that late-maturing, tall, and two-row lines tended to have lower disease, whereas hull type did not show a significant correlation with FHB. Several lines with high and stable FHB resistance similar to that of the resistant checks were identified. These could be used in breeding programs as resistance sources or be registered as new cultivars if their overall attributes meet commercial standards.

Exploring the Serbian GenBank barley (Hordeum vulgare L. subsp. vulgare) collection for powdery mildew resistance

Unlocking resistance genes in genbank collections are of prime importance for securing sustainable crop production. In this regard, the Serbian GenBank barley collection, comprising 93 local landraces and 36 commercial cultivars and elite barley breeding lines, was screened for novel resistances to powdery mildew (Blumeria graminis f. sp. hordei) using a set of 28 isolates with a wide spectrum of virulences/avirulences. No line was resistant to all the isolates, but one and three accessions showed resis- tance to 27 and 26 isolates, respectively. Twenty landraces (21.51 %) and ten cultivars (27.78 %) exhibited resistance to 50 % of the isolates. Infection type 2 was most frequent among resistant accessions. Nine B. graminis isolates were sufficient for gene postulation in 73 barley lines. In total, thirty-five different resistance spectra were recorded and the following known resistance genes were postulated namely, Mlra, Mlh, Mla12, Mla7(Mlu), Mlg, MlLa, Mla6, Mla7, Mlt, Mla22, Mlat, Mla1, Mlk. The majority of resistance profiles was constituted by only one line. Unidentified genes alone or in combination were proposed for twenty landraces and six cultivars. This report demonstrated that the barley collection held at the Serbian GenBank could be exploited as a new source for powdery mildew resistance.

A genome-wide association study of malting quality across eight U.S. barley breeding programs.

We report malt quality QTLs relevant to breeding with greater precision than previous mapping studies. The distribution of favorable alleles suggests strategies for marker-assisted breeding and germplasm exchange. This study leverages the breeding data of 1,862 barley breeding lines evaluated in 97 field trials for genome-wide association study of malting quality traits in barley. The mapping panel consisted of six-row and two-row advanced breeding lines from eight breeding populations established at six public breeding programs across the United States. A total of 4,976 grain samples were subjected to micro-malting analysis and mapping of nine quality traits was conducted with 3,072 SNP markers distributed throughout the genome. Association mapping was performed for individual breeding populations and for combined six-row and two-row populations. Only 16% of the QTL we report here had been detected in prior bi-parental mapping studies. Comparison of the analyses of the combined two-row and six-row panels identified only two QTL regions that were common to both. In total, 108 and 107 significant marker-trait associations were identified in all six-row and all two-row breeding programs, respectively. A total of 102 and 65 marker-trait associations were specific to individual six-row and two-row breeding programs, respectively indicating that most marker-trait associations were breeding population specific. Combining datasets from different breeding program resulted in both the loss of some QTL that were apparent in the analyses of individual programs and the discovery of new QTL not identified in individual programs. This suggests that simply increasing sample size by pooling samples with different breeding history does not necessarily increase the power to detect associations. The genetic architecture of malting quality and the distribution of favorable alleles suggest strategies for marker-assisted selection and germplasm exchange.

Selection footprints in barley breeding lines detected by combining genotyping-by-sequencing with reference genome information

This study is a retrospective analysis of an elite cross from the Spanish National Barley Breeding Program. This was the most successful cross produced in the breeding program in the past 20 years. The progeny from this cross has been investigated at two points in the program, before and after selection, through the analysis of allelic frequencies at a number of genetic loci with molecular markers. Shifts in allelic frequencies after selection allowed the identification of genomic regions with selection footprints likely due to the breeding process. The cross was replicated in three different years, and therefore, the three progenies represent different selection histories but, in all cases, were preferentially selected compared to the lines from other crosses used in the program. The progenies were sampled at two generations, before conscious selection (F2) and after six generations of selection (F8). The F2 plants were genotyped with microsatellites, whereas 31 F8 lines were surveyed for SNP and presence/absence variation polymorphisms using a genotyping-by-sequencing system (DArTseq). The DArTseq markers were aligned to the barley physical map, and, after curation, over 3,000 were still available for the analysis. Overall, 15 genomic regions in the F8 lines had allele frequencies beyond chosen thresholds, indicating selection, eight toward parent Orria and seven toward Plaisant. These selection footprints partially validated QTLs detected through classical linkage mapping in a RIL population of the same cross. These validated selection footprints convey useful information for barley breeding, either through marker-assisted selection or through genomic selection.

Evaluation of winter barley breeding lines for productivity and adaptability under environments of forest- steppe of Ukraine

Purpose. To evaluate new winter barley breeding lines under environments of Forest-Steppe of Ukraine for productivity and resistance to abiotic and biotic factors, to select the best ones for complex of agronomic traits as candidates-varieties to be transferred to State Strain Testing.Material and methods. The study was conducted at Breeding Barley Laboratory of the V. M. Remeslo Myronivka Institute of Wheat of NAAS in 2009-2014. Winter barley breeding lines of competitive strain test of were the object of the research. Field evaluation for winter hardiness, duration of cropping season, resistance to lodging and to major leaf diseases was carried out. Adaptability indices were calculated by yield performance according to conventional methods.Results. In 2009-2010 field evaluation and rejection of breeding lines in control nursery and prove preliminary testing for winter hardiness has been carried out. Subsequently under relatively favorable wintering conditions the breeding lines were studied in the competitive strain testing for morpho-physiological traits related to winter barley winter hardiness such as sugar levels accumulated in tillering nodes at the moment of stopping growth and development of apical points in autumn and winter periods.With a number of methods to assess the adaptability mathematical and statistical analysis of yield for 40 winter barley breeding lines in 2012-2014 was carried out and parameters of plasticity and stability were defined. Based on the indices defined ranking and calculation of adaptability rating were carried out. In addition, weather conditions during years of research were favorable to objective evaluation of breeding lines for resistance to lodging and several leaf diseases - powdery mildew, barley leaf stripe, net blotch, spot blotch and barley leaf rust. Breeding lines that combine higher levels of yield and resistance and moderate resistance to individual or set of the factors mentioned above in field conditions were identified.Conclusions. Resulted from a comprehensive study in competitive strain testing of MIW breeding lines Pallidum 4816 (Luxor / Myronivs’ky 87), Pallidum 4857 (Osnova / Myronivs’ky 87), Pallidum 4659 (Erfa / Radical // Kromoz) possessing the most optimal ratio of yield potential, parameters of adaptability, resistance and moderate resistance to abiotic and biotic factors were singled out. These lines will be transferred to the State Strain Testing of Ukraine as new winter barley varieties.

The application of microsatellite analysis in barley malting quality breeding programmes

A set of 43 microsatellite loci was used to characterise the malting barley varieties and breeding lines used for the Protected Geographical Indication (PGI) “České pivo” (“Czech beer”) and for other beer types. Genotype data were compared with technological malting quality parameters. The analysis of variance showed significant differences between varieties used for the given PGI and varieties used for other beer types in six variables. Three clusters of varieties specific to the PGI and three clusters specific to  malting barley genotypes for other beer types were identified using a Bayesian approach. The remaining four clusters expressed  effects of parent lines. The discrimination analysis based on malting quality and molecular variables identified only one barley breeding line suitable for the PGI “České pivo”.

Association Mapping of Agronomic QTLs in U.S. Spring Barley Breeding Germplasm

The use of genome‐wide association studies (GWAS) to detect quantitative trait loci (QTL) controlling complex traits has become a popular approach for studying key traits in crop plants. The goal of this study was to identify the genomic regions of barley (Hordeum vulgare L.) that impact five agronomic and one quality trait in U.S. elite barley breeding lines, as well as to identify markers tightly linked with these loci for further use in barley improvement. Advanced recombinant inbred lines submitted to the U.S. Barley Coordinated Agricultural Project (CAP) were genotyped using a platform of 3072 single nucleotide polymorphism (SNP) markers from the barley oligonucleotide pool assays (BOPAs) 1 and 2. In each of 4 yr, approximately 770 lines were evaluated in a replicated, randomized complete block design under both irrigated and dryland conditions. This gave an overall population size of >3000 lines, which we analyzed in a hierarchical fashion, including analyzing the lines in aggregate using a mixed model to account for population structure and relatedness among the lines. We identified 41 significant marker–trait associations, of which 31 had been previously reported as QTL using biparental mapping techniques; 10 novel marker‐trait associations were identified. The results of this work show that genes with major effects are still segregating in U.S. barley germplasm and demonstrate the utility of GWAS in barley breeding populations.