Winter Wheat Breeding Lines Research Articles

GWAS for Fusarium Head Blight Related Traits in Winter Wheat (Triticum Aestivum L.) in an Artificially Warmed Treatment

Global temperature increases will affect Fusarium head blight (FHB) levels in wheat (Triticum aestivum L.). A pressing question is whether current sources of resistance will be effective in a warmer environment. We evaluated phenotypic response to disease in 238 soft winter wheat breeding lines and cultivars grown in 2015–2016 and 2016–2017 under control and warmed (+3 °C) conditions. Warming was achieved with heating cables buried 3 cm in the rhizosphere. We measured heading date, plant height, yield, FHB rating, Fusarium damaged kernels (FDK), deoxynivalenol (DON), leaf blotch rating, powdery mildew rating and leaf rust rating. There were significant (p < 0.01) differences among genotypes for all traits measured. Genome-wide association study (GWAS) identified 19 and 10 significant SNPs in the control and warmed treatments, respectively. FDK and DON levels were often significantly (p < 0.05) higher in warmed than in control when we contrasted alleles at important quantitative trait locus (QTL) such as Fhb1, Rht-B1 and D1 and all vernalization and photoperiod loci. Increased rhizosphere temperature resulted in a significantly (p < 0.01) earlier heading date (~3.5 days) both years of the study. Rank correlation between warmed and control treatments was moderate (r = 0.56). Though encouraging, it indicates that selection for performance under warming should be carried out in a warmed environment.

Characterizing and Validating Stripe Rust Resistance Loci in US Pacific Northwest Winter Wheat Accessions (Triticum aestivum L.) by Genome-wide Association and Linkage Mapping.

Stripe rust resistance is a critical need for wheat cultivars in the US Pacific Northwest (PNW). Our previous genome-wide association study (GWAS) for stripe rust resistance in a set of PNW winter wheat accessions (Panel-2) identified multiple marker-trait associations (MTAs) for both all-stage and field resistance. In this study, we conducted additional GWAS using a different set of PNW winter wheat accessions (Panel-1) that contained recently bred soft white winter wheat breeding lines and cultivars. A total of 12 all-stage resistance MTAs and eight field resistance MTAs were identified. Within these MTAs, nine MTAs for all-stage resistance and two MTAs for field resistance were located distinctly from previously characterized genes and likely represent novel loci. Markers IWB60567 (1B), IWB24342 (2A), and IWB46564 (2B) explained the largest phenotypic variances for disease responses. The analysis confirmed that MTAs on chromosome 1B were indeed the same as identified in Panel-2 and that MTAs on chromosome 2A were likely and closely linked to another field resistance QTL, (Panel-2). Haplotypes for MTAs on chromosome 1B, , and linked loci on chromosome 2A provide useful information for marker development and introgression of these QTL into wheat breeding programs.

Genome-Wide Association Studies and Comparison of Models and Cross-Validation Strategies for Genomic Prediction of Quality Traits in Advanced Winter Wheat Breeding Lines.

The aim of the this study was to identify SNP markers associated with five important wheat quality traits (grain protein content, Zeleny sedimentation, test weight, thousand-kernel weight, and falling number), and to investigate the predictive abilities of GBLUP and Bayesian Power Lasso models for genomic prediction of these traits. In total, 635 winter wheat lines from two breeding cycles in the Danish plant breeding company Nordic Seed A/S were phenotyped for the quality traits and genotyped for 10,802 SNPs. GWAS were performed using single marker regression and Bayesian Power Lasso models. SNPs with large effects on Zeleny sedimentation were found on chromosome 1B, 1D, and 5D. However, GWAS failed to identify single SNPs with significant effects on the other traits, indicating that these traits were controlled by many QTL with small effects. The predictive abilities of the models for genomic prediction were studied using different cross-validation strategies. Leave-One-Out cross-validations resulted in correlations between observed phenotypes corrected for fixed effects and genomic estimated breeding values of 0.50 for grain protein content, 0.66 for thousand-kernel weight, 0.70 for falling number, 0.71 for test weight, and 0.79 for Zeleny sedimentation. Alternative cross-validations showed that the genetic relationship between lines in training and validation sets had a bigger impact on predictive abilities than the number of lines included in the training set. Using Bayesian Power Lasso instead of GBLUP models, gave similar or slightly higher predictive abilities. Genomic prediction based on all SNPs was more effective than prediction based on few associated SNPs.

秋まき小麦品種における穂発芽抵抗性の改善 : IV. 秋まき小麦選抜系統と穂発芽耐性春まき小麦の比較

秋まき小麦品種における穂発芽抵抗性の改善 : IV. 秋まき小麦選抜系統と穂発芽耐性春まき小麦の比較

How do eyespot resistance genes transferred into winter wheat breeding lines affect their yield?

Abstract Eyespot can reduce yields, even up to 50%. There are four genetically characterized resistances in wheat varieties, controlled by: (1) the Pch1 gene, transferred from Aegilops ventricosa; (2) the Pch2 gene, originating from wheat variety Capelle Desprez; (3) the Pch3 gene, originating from Dasypyrum villosum; and (4) the Q.Pch.jic-5A gene, a quantitative trait locus (QTL) located on chromosome 5A of Capelle Desprez. However, those loci have drawbacks, such as linkage of Pch1 with deleterious traits and limited effectiveness of Pch2 against the disease. Here we present an initial study which aims to characterize wheat pre-registration breeding lines carrying 12 eyespot resistance genes, consider their resistance expression in inoculation tests and the influence of resistance genotypes on the yield. We selected four groups of breeding lines, carrying: (1) the Pch1 gene alone: one line; (2) the Pch2 gene alone: four lines; (3) the Q.Pch.jic-5A gene alone: one line; and (4) Pch1 + Q.Pch.jic-5A: three lines. For the first time, the effect of the combination of Pch1 and Q.Pch.jic-5A genes was compared with resistance conferred by Pch1 or Q.Pch.jic-5A alone. We found significant differences between infection scores evaluated in resistant lines carrying Pch1 and Q.Pch.jic-5A alone, while no differences in terms of the level of resistance expression were detected between Pch1 alone and Pch1 + Q.Pch.jic-5A, and between wheat lines carrying Pch1 and Pch2 alone. Moreover, we demonstrated that the Pch1 gene, together with an Ae. ventricosa segment, caused statistically significant yield losses, both as a single eyespot resistance source or in a combination with Q.Pch.jic-5A. Yield scores showed that wheat lines with Q.Pch.jic-5A had the highest yields, similar to the yielding potential of Pch2-bearing lines and control varieties.

Identifying Rare FHB-Resistant Segregants in Intransigent Backcross and F2 Winter Wheat Populations.

Fusarium head blight (FHB), caused mainly by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schwein.(Petch)] in the US, is one of the most destructive diseases of wheat (Triticum aestivum L. and T. durum L.). Infected grain is usually contaminated with deoxynivalenol (DON), a serious mycotoxin. The challenge in FHB resistance breeding is combining resistance with superior agronomic and quality characteristics. Exotic QTL are widely used to improve FHB resistance. Success depends on the genetic background into which the QTL are introgressed, whether through backcrossing or forward crossing; QTL expression is impossible to predict. In this study four high-yielding soft red winter wheat breeding lines with little or no scab resistance were each crossed to a donor parent (VA01W-476) with resistance alleles at two QTL: Fhb1 (chromosome 3BS) and QFhs.nau-2DL (chromosome 2DL) to generate backcross and F2 progeny. F2 individuals were genotyped and assigned to 4 groups according to presence/ absence of resistance alleles at one or both QTL. The effectiveness of these QTL in reducing FHB rating, incidence, index, severity, Fusarium-damaged kernels (FDK) and DON, in F2-derived lines was assessed over 2 years. Fhb1 showed an average reduction in DON of 17.5%, and conferred significant resistance in 3 of 4 populations. QFhs.nau-2DL reduced DON 6.7% on average and conferred significant resistance in 2 of 4 populations. The combination of Fhb1 and QFhs.nau-2DL resistance reduced DON 25.5% across all populations. Double resistant lines had significantly reduced DON compared to double susceptible lines in 3 populations. Backcross derived progeny were planted in replicated yield trials (2011 and 2012) and in a scab nursery in 2012. Several top yielding lines performed well in the scab nursery, with acceptable DON concentrations, even though the average effect of either QTL in this population was not significant. Population selection is often viewed as an “all or nothing” process: if the average resistance level is insufficient, the population is discarded. These results indicate that it may be possible to find rare segregants which combine scab resistance, superior agronomic performance and acceptable quality even in populations in which the average effect of the QTL is muted or negligible.

Genome-Wide Association Mapping of Fusarium Head Blight Resistance in Wheat using Genotyping-by-Sequencing.

Fusarium head blight (FHB) is one of the most important wheat ( L.) diseases worldwide, and host resistance displays complex genetic control. A genome-wide association study (GWAS) was performed on 273 winter wheat breeding lines from the midwestern and eastern regions of the United States to identify chromosomal regions associated with FHB resistance. Genotyping-by-sequencing (GBS) was used to identify 19,992 single-nucleotide polymorphisms (SNPs) covering all 21 wheat chromosomes. Marker-trait associations were performed with different statistical models, the most appropriate being a compressed mixed linear model (cMLM) controlling for relatedness and population structure. Ten significant SNP-trait associations were detected on chromosomes 4A, 6A, 7A, 1D, 4D, and 7D, and multiple SNPs were associated with on chromosome 3B. Although combination of favorable alleles of these SNPs resulted in lower levels of severity (SEV), incidence (INC), and deoxynivalenol concentration (DON), lines carrying multiple beneficial alleles were in very low frequency for most traits. These SNPs can now be used for creating new breeding lines with different combinations of favorable alleles. This is one of the first GWAS using genomic resources from the International Wheat Genome Sequencing Consortium (IWGSC).

Comparative evaluation of predictable and unpredictable environments as backgrounds for selection to adaptive ability

The research of 122 breeding lines of winter wheat to adaptability have been carried out for three years at three points. Samples for ecological variety testing were determined which have both high and average stability and plasticity, high average yield and are promising for qualified examination. The environments are analyzed for differentiating ability. Environments were selected which allow to identify genotypes for yield potential and adaptive ability. It is established that the parameters of adaptive ability and stability of winter wheat samples obtained during cultivation both in various geographical locations and at one point during some years were closely correlated. This confirms the hypothesis that the genotype estimate for adaptive ability in one location is reliable. The connection level was average only for the variance of genotype–environment interaction. However, this parameter is not principal therefore this connection level does not restrict significantly the use of the method in general.

Molecular characterization of three transgenic high molecular weight glutenin subunit events in winter wheat

Lab-on-a-chip separation and asymmetrical flow field-flow fractionation and multi-angle laser light scattering were used to characterize the polymeric protein fraction of three transgenic high molecular weight glutenin subunit (HMW-GS) events in advanced breeding lines of hard winter wheat (Triticum aestivum L.). In the transgenic event B52a6, HMW-GS 1Dy10 was produced at respective rates of 6.7 and 4.6 times higher than those of non-transgenic B52a6 siblings and control cultivars. In transgenic event Dy10-E, the observed amount of 1Dy10 was approximately 5.7 and 5.8 fold greater than those of non-transgenic Dy10-E derivatives and controls. Event Dx5 + Dy10-H over-produced HMW-GS 1Dx5 at rates of approximately five to six fold higher than l non-transgenic siblings and controls, respectively. All three transgenic events exhibited significantly greater average molecular mass of glutenin than those of both controls and the respective non-transgenic siblings. The transgenic Dy10-E event displayed the largest polymer molecular weight distribution. The percentage of protein found in polymeric form, however, did not increase in any of the three events. Technological properties, including mixograph time to peak, mixograph tolerance, bake mix time and loaf volume were strongly dependent upon the average Mw and glutenin quantity.

The estimation of the adaptive abilities and stability of varieties and breeder lines in the bread wheat breeding

Nowadays, breeders are challenged to create wheat varieties are not only high performance but also resistant to biotic and abiotic environmental factors.The aim of the study was to determine the adaptive ability of new breeding lines of winter wheat.Conditions and Methods. We used the method of genetic analysis of Kilchevskii - Khotilova that is based on the genotypes tested in different environments and allow identifying general and specific adaptive ability of genotypes and their stability. It is possible to estimate the breeding value of genotype and lead selection for adaptive ability. To determine the adaptive ability of the samples were trying to create the most differentiated growing conditions. The study was conducted during 2010 - 2013 years in three points : Kopyliv experimental field (Makarov district, Kiev region), Cherkasy ES (Smila district, Cherkasy region), Panfyly ES (Yagotyn district, Kiev region).Results and discussion. Analyzed 122 breeding lines of winter wheat for adaptive ability. As a growing conditions used geographic locations and conditions of the year. In terms of productivity, adaptive ability and stability and using variety adaptability rating (VAR) identified a number of lines. Among them were highly stable lines as well as samples with average stability and plasticity. The used method for determination of VAR, in our opinion, needs some work by introducing a coefficient of relevance of indicators

Evaluation of freezing tolerance of winter wheat (Triticum aestivum L.) under controlled conditions and in the field

Freezing tolerance of winter wheat (Triticum aestivum L.) is one of the main factors governing winter survival. To avoid winterkill it is very important to choose freezing tolerant wheat genotypes. Experiments were carried out to evaluate freezing tolerance of winter wheat varieties and breeding lines under field and controlled conditions with cold acclimation and with no cold acclimation stage. Field experiments were done for two years during the winters of 2010–2011 and 2011–2012. The evaluation of winter hardiness was conducted in April of 2011 and 2012 by visual scoring on a 1–9 score basis (score 1 – all plants were killed, score 9 – all plants survived). Wheat genotypes under investigation experienced very different climatic conditions in the field during the two winters. Consequently, no correlation between winter hardiness scores of 2010–2011 and 2011–2012 winters was observed. Winter hardiness scores ranged from 1.0 (WW-8) to 7.6 (‘Zentos’) after 2010–2011 winter, whereas winter hardiness scores varied from 5.8 (WW-31) to 7.8 (‘Kovas DS’) after 2011–2012 winter. Freezing tolerance of winter wheat genotypes was also assessed in the controlled conditions by measuring chlorophyll fluorescence parameter Fv/Fm in leaves and percentage survival of plants after the freezing test. High correlation (r = 0.88, p < 0.01) between freezing test survival of non-acclimated wheat and Fv/Fm ratio showed that this method can speed up the selection for freezing tolerance by evaluating wheat genotypes immediately after the test. Results of our study showed low negative, but significant relationship (r = −0.41, p < 0.05) between 2010–2011 winter hardiness scores in the field and freezing test survival of non-acclimated plants in the laboratory experiment. Wheat genotypes that quickly lose winter hardiness have higher freezing tolerance without hardening stage. Our results support the hypothesis of two separate genetic systems of freezing tolerance in winter wheat which are determined by duration and rate of gene expression during cold acclimation.

Isolation of differentially expressed genes in wheat caryopses with contrasting starch granule size

AbstractIn order to identify genes responsible for starch granule initiation during early development of wheat caryopsis, nine winter wheat breeding lines were studied. Two breeding lines, which are the most diverse in A-type granule size (26.85 µm versus 23.65 µm) were chosen for further differential gene expression analysis in developing caryopses at 10 and 15 days post-anthesis (DPA). cDNA-amplified fragment length polymorphism (cDNA-AFLP) analysis resulted in 384 transcript-derived fragments, out of which 18 were identified as being differentially expressed. Six differentially expressed genes, together with the six well-known starch biosynthesis genes, were chosen for semi-quantitative gene expression analysis in developing wheat caryopses at 10 and 15 DPA. This study provides genomic information on 18 genes differentially expressed at early stages of wheat caryopses development and reports on the identification of genes putatively involved in the production of large A-type granules. These genes are targets for further validation on their role in starch granule synthesis control and provide the basis for the development of DNA marker tools in winter wheat breeding for enhanced starch quality.

Reaction of winter wheat genotypes to infection by Mycosphaerella graminicola(Fuckel) Schroeter

The response of Polish winter wheat genotypes to &lt;i&gt;M.graminicola&lt;/i&gt; (preliminary experiments and cultivar collections) was observed in different regions of Poland. Observations were carried out in 1995-1999. The winter wheat genotypes showed a broad spectrum of reaction to this pathogen. Between 1997 and 1999 the highest degree of infection on winter wheat breeding lines was noted in Kończewice. During this time no genotypes free from infection were observed (preliminary breeding experiments). Cultivars with no symptoms of &lt;i&gt;Septoria tritici&lt;/i&gt; blotch (Leszczyńska Wczesna and Żelazna) were found among old genotypes in Słupia Wielka only in earlier experiments (1995-1996). In the years 1997-1999 the winter wheat cultivars were classified into groups on the basis of their response to the pathogen. The degree of infection for the majority cultivars was quite high.

Occurrence of Septoria tritici blotch in 1994-1996

The aim of the work was to study an occurrence and intensity of septoria tritici blotch on wheat in different regions of Poland as well as reaction of winter wheat cultivars and breeding lines to infection by &lt;em&gt;Mycosphaerella graminicola&lt;/em&gt; (Fuckel) Schroeter (an. &lt;em&gt;Septoria tritici&lt;/em&gt; ( Rob. ex Desm .) under field conditions. Observation conducted during 1994-1996 indicated on occurrence of septoria tritici blotch each year and on important infection degree of winter wheat by &lt;em&gt;Mycosphaerella gruminicola&lt;/em&gt; in some regions of the country. The highest infection was noted in 1995 and the lowest in 1994. Infection degree for majority of cultivars was quite high. Some cultivars and lines were characterized by very high infection. Among them were the old (Kujawianka Więcławska and Wysokolitewka Sztywnosłoma) and the newest (Tercja) cultivars. On some old cultivars (Leszczyńska Wczesna and Żelazna) even no traces of infection were observed although favourable weather condition existance and the presence of neighbourhood diseased plants. Field observation of cultivars and breeding lines showed different reaction of tested wheat genotypes to &lt;em&gt;Mycosphaerella graminicola&lt;/em&gt; infection.

A Rapid, Small‐Scale Sedimentation Method to Predict Breadmaking Quality of Hard Winter Wheat

ABSTRACTBreeders and processors are always looking for rapid and accurate methods to evaluate wheat (Triticum aestivum L.) quality. The objective of this study was to develop a rapid, small‐scale method to accurately determine breadmaking quality for early generation hard winter wheat (HWW) breeding lines by combining the solutions used in the sodium dodecyl sulfate (SDS) sedimentation method (American Association of Cereal Chemists [AACC] 56‐70 [AACC, 2000]) and the centrifugation process found within the solvent retention capacity (SRC) method (AACC 56‐11 [AACC, 2000]). A preliminary test of the hybrid SDS‐SRC method was performed on eight HWW varieties and compared to AACC (56‐70) and in‐house Hard Winter Wheat Quality Laboratory (HWWQL) methods to show proof of concept. Further validation of the hybrid method was conducted on a diverse set of 53 HWW varieties. The hybrid method was performed in 66% less time than AACC 56‐70 and HWWQL methods. Furthermore, sample size was reduced from 6 g for the AACC method to 1 g for the hybrid method. Results obtained from the hybrid method exhibited a higher correlation to bread loaf volume (r ≥ 0.84) compared to results from the AACC method (r &gt; 0.42) and HWWQL method (r ≥ 0.64) for wheat flour. Due to enhanced speed, accuracy, and simplicity the hybrid SDS‐SRC sedimentation method may prove useful in breeding programs, grain elevators, and other scenarios where rapid assessment of end‐use quality determination is required.

Characterization of Resistance to Stripe Rust in Contemporary Cultivars and Lines of Winter Wheat from the Eastern United States.

Stripe rust, caused by Puccinia striiformis f. sp. tritici, has been an important disease of winter wheat (Triticum aestivum) in the eastern United States since 2000, when a new strain of the pathogen emerged. The new strain overcame the widely used resistance gene, Yr9, and was more aggressive and better adapted to warmer temperatures than the old strain. Host resistance is the most effective approach to manage stripe rust. Winter wheat lines with resistance to the new strain in the field are common, but the genes conferring this resistance are mostly unknown. The objectives of this research were to characterize the all-stage resistance and adult-plant resistance (APR) to stripe rust in a representative group of contemporary winter wheat cultivars and breeding lines and to identify the resistance genes when possible. Of the 50 lines evaluated for all-stage resistance at the seedling stage, nearly all were susceptible to the new strain. Based on a linked molecular marker, seven lines had resistance gene Yr17 that confers resistance to both old and new strains; however, this resistance was difficult to identify in the seedling stage. Of the 19 lines evaluated for APR, all expressed APR compared with a very susceptible check. Nine had race-specific APR to the new strain and nine had APR to both old and new strains. The remaining line, 26R61, had all-stage resistance to the old strain (conferred by resistance gene Yr9) and a high level of APR to the new strain. APR was expressed as low infection type, low percent leaf area diseased, and long latent period at heading stage under both low and high temperature regimes and could be identified as early as jointing stage. Based on tests for linked molecular markers, the most widely used slow-rusting APR genes, Yr18 and Yr29, were not present in any of the lines. The results of this research indicate that effective all-stage resistance was conferred only by Yr17 and that APR was common and likely conferred by unknown race-specific genes rather than genes conferring slow rusting that are more likely to be durable.

Identification of Ug99 stem rust resistance loci in winter wheat germplasm using genome-wide association analysis

The evolution of a new race of stem rust, generally referred to as Ug99, threatens global wheat production because it can overcome widely deployed resistance genes that had been effective for many years. To identify loci conferring resistance to Ug99 in wheat, a genome-wide association study was conducted using 232 winter wheat breeding lines from the International Winter Wheat Improvement Program. Breeding lines were genotyped with diversity array technology, simple sequence repeat and sequence-tagged site markers, and phenotyped at the adult plant stage for resistance to stem rust in the stem rust resistance screening nursery at Njoro, Kenya during 2009-2011. A mixed linear model was used for detecting marker-trait associations. Twelve loci associated with Ug99 resistance were identified including markers linked to known genes Sr2 and Lr34. Other markers were located in the chromosome regions where no Sr genes have been previously reported, including one each on chromosomes 1A, 2B, 4A and 7B, two on chromosome 5B and four on chromosome 6B. The same data were used for investigating epistatic interactions between markers with or without main effects. The marker csSr2 linked to Sr2 interacted with wPt4930 on 6BS and wPt729773 in an unknown location. Another marker, csLV34 linked to Lr34, also interacted with wPt4930 on 6BS and wPt4916 on 2BS. The frequent involvement of wPt4916 on 2BS and wPt4930 on 6BS in interactions with other significant loci on the same or different chromosomes suggested complex genetic control for adult plant resistance to Ug99 in winter wheat germplasm.

Registration of ‘Anton’ Hard White Winter Wheat

Low levels of the grain enzyme polyphenol oxidase (PPO) are a necessary attribute of any newly developed hard white wheat (Triticum aestivum L.) adapted to the Great Plains. Low PPO correlates with enhanced end‐use quality, including the final product color in noodle applications. Few wheats with this necessary characteristic presently are available. The objective of this study was to develop a hard winter wheat adapted to the region that possesses both low levels of grain PPO and quality characteristics that would allow its utilization in domestic bread‐making applications. This goal was achieved via the development and release in December 2007 of ‘Anton’ (Reg. No. CV‐1057, PI 651044) hard white winter wheat by the USDA‐ARS and the Nebraska Agricultural Experiment Station. Anton was released primarily for its low levels of PPO. Flour‐PPO levels of Anton (tested under the experimental designation NW98S097) were significantly lower than all other entries in the 2003 and 2004 USDA‐ARS coordinated Northern Regional Performance nursery. Polyphenol oxidase levels of Anton in grain from the 2005 University of Nebraska cultivar performance trials were not significantly different from those of the low‐PPO cultivar ‘Platte’ and were significantly lower than those of several additional current hard white winter wheat cultivars and breeding lines. Anton was selected from the cross WA691213‐27/N86L177//Platte.

Evaluation of winter wheat breeding lines for traits related to nitrogen use under organic management

There is growing interest in breeding crop cultivars specifically for organic agriculture, based on recognized differences in environmental conditions and management in organic systems compared to conventional systems, and especially due to environmental heterogeneity among and within individual organic systems. There is a need to develop effective strategies for improving crop performance in organic systems through plant breeding. This study evaluated 12 diverse winter wheat breeding lines chosen from conventional and organic breeding nurseries, six historic varieties, and an experimental perennial wheat population under organic management in the Inland Pacific Northwest region of the USA. A randomized complete block design with three replications in two locations over 2 years was used. Based on an analysis of variance, significant genetic differences and crossover interactions across years were found for grain yield, grain percent nitrogen, grain total nitrogen, and aboveground biomass. There were no main effects of locations or location-by-genotype effects for these traits. Based on comparisons among these breeding lines, it appears that there is a possibility of selecting for performance across a limited ecological zone as top-yielding lines were the same in both locations. However, individual entries may have variable performance across years within a single location so selection for stability of performance over years is also necessary. Using an analysis of direct measures of grain yield and grain %N in each location–year combination and overall, we identified breeding lines with relatively high yield, acceptable grain protein, and stable performance over all four location–year combinations. The use of indirect measures or index selection to simultaneously select for grain yield and protein did not appear to be more effective than direct selection based on yield and grain %N measured under organic management.

Quality and Agronomic Effects of Three High‐Molecular‐Weight Glutenin Subunit Transgenic Events in Winter Wheat

ABSTRACTQuality and agronomic effects of three transgenic high molecular weight glutenin subunit (HMW‐GS) events were characterized in advanced‐generation breeding lines of hard winter wheat (Triticum aestivum L.) in three Nebraska crop years. Two of the transgenic events studied, Dy10‐E and B52a‐6, overexpress HMW‐GS 1Dy10, while the third event, Dx5 +Dy10‐H, overexpresses HMW‐GS 1Dx5 and, to a much lesser extent, 1Dy10. In addition, novel proteins possessing solubility characteristics defined as HMW‐GS were present in Dx5+Dy10‐H and B52a‐6. Average grain yield of lines derived from the three transgenic events was statistically lower than that of a group of control cultivars and advanced breeding lines, but not lower than the mean values of respective nontransgenic siblings. Grain hardness was influenced by one of the events. Dx5+Dy10‐H produced harder kernels than controls, its nontransgenic siblings, and the two additional transgenic events. All three events produced doughs with unusual mixing properties, although not likely to be directly useful in commercial applications. As a consequence, loaf volumes were depressed to variable degrees by the three events. The results indicated that over‐expression of HMW‐GS could eventually lead to improved breadmaking quality by optimizing the level of overexpression or by development and characterization of additional events.