HMW Glutenin Research Articles

Grain storage protein concentration and composition of winter wheat (Triticum aestivum L.) as affected by waterlogging events during stem elongation or ear emergence

Maintaining grain quality of winter wheat under abiotic stresses is important for end-use functional properties. While changes in protein concentration and protein composition have been shown for drought and heat events, knowledge on effects of waterlogging on protein quality are scarce. Therefore, two winter wheat cultivars differing in baking properties were cultivated in a large-scale container experiment and exposed to waterlogging for 14 d at two different growth stages: (1) at BBCH 31 (stem elongation) and (2) at BBCH 51 (beginning of ear emergence). Analysis of protein concentration revealed a significant increase, but protein content per grain was decreased. Analysis of protein composition displayed significant changes after both waterlogging treatments. Waterlogging at stem elongation resulted in a decreased concentration of ω-gliadins. HMW glutenins increased after waterlogging at stem elongation and at ear emergence. In both cultivars, LMW B-type glutenins decreased after waterlogging at stem elongation or at ear emergence. In this study, we could show that waterlogging, occurring in generative developmental stages, enhance grain protein concentration, but not necessarily protein content, and that waterlogging causes shifts in grain protein composition.

The effects of various plant protection methods on the development of Zymoseptoria tritici and Cephalosporium gramineum, grain yield and protein profile

ABSTRACTSeptoria leaf blotch progresses rapidly, leading to the development of Zymoseptoria titici forms resistant to fungicides. Cephalosporium stripe is caused by Cephalosporium gramineum. The aim of this study was to evaluate the effectiveness of selected pesticides in limiting the symptoms of both diseases on winter wheat leaves, and to determine their influence on grain yield and the content and composition of protein fractions in wheat kernels. Propiconazoles were most effective in inhibiting the development of Septoria leaf blotch (symptoms were reduced from 54.7% to 78.6%). Strobilurins were less effective due to the presence of isolates with the G143A mutation. Symptoms of Cephalosporium stripe were rarely observed, and protective treatments did not reduce their severity. The highest content of grain protein (14.81%) was found in plants most intensely protected with the fungicides containing fenpropimorph, pyraclostrobin and epoxiconazole. The principal component analysis revealed that the plant protection method influenced the grain protein profile. The accumulation of HMW glutenins and α/β gliadins was mutually interrelated and higher in high-input treatments; control grain was characterized by close relationships between ω-gliadins, LMW glutenins, albumins and globulins, whereas low-input treatments influenced mostly γ-gliadins.

Geographical comparison of genetic diversity in Asian landrace wheat (Triticum aestivum L.) germplasm based on high-molecular-weight glutenin subunits

Glutenin largely determines wheat bread baking quality. As high-molecular-weight glutenin subunit (HMW-GS), related to Glu-1 loci, determines wheat flour elasticity, it correlates strongly with bread-making quality. This study was aimed at clarifying genetic variations in bread-making characteristics between East and West Asian wheat landrace germplasms, by investigating HMW-GS allelic composition of 1068 wheat accessions. Herein, the accession number having reported HMW-GS pattern in previous studies was 855. However, the accession number with newly detected HMW-GS patterns was 114. These new HMW-GS patterns were classified into 4 types based on similarity. Eight Korean accessions with these four types were identified. Concerning landrace germplasm nature, 99 accessions showed heterogeneous patterns caused by seed mixture. The Glu-1 loci allelic variation analysis, revealed that the percentages of Glu-A1c (73.6%), Glu-B1b (60.2%), and Glu-D1a (68.5%) were highest at Glu-A1, Glu-B1, and Glu-D1 loci, respectively. The incidence of preferable alleles for bread baking was high in Chinese accessions. In bread-making quality evaluation using Glu-1 score, 24 among 35 accessions with full score were from China. The polymorphic information content index of each origin based on HMW glutenin subunit combination showed that West Asian and neighboring-regional landraces, excluding Afghanistan ones, were more diverse than East Asian landraces excluding Chinese ones. Cluster analysis based on Glu-1 allelic combination showed that many Korean, Japanese, and Afghan accessions were in the same group. However, many Chinese and other West Asian accessions were in the other group despite geographical distance.

An Analysis to Explore Divergence of HMW Glutenin Subunits in High-Yield Indian Wheat of Different Production Environments

An Analysis to Explore Divergence of HMW Glutenin Subunits in High-Yield Indian Wheat of Different Production Environments

Novel D-hordein-like HMW Glutenin Sequences Isolated from Psathyrostachys juncea by Thermal Asymmetric

New high-molecular-weight glutenin (HMW glutenin) sequences isolated from six Psathyrostachys juncea accessions by thermal asymmetric interlaced PCR differ from previous sequences from this species. They showed novel modifications in all of the structural domains, with unique C-terminal residues, and their N-terminal lengths were the longest among the HMW glutenins reported to date. In their repetitive domains, there were three repeatable motif units: 13-residue [GYWH(/I/Y)YT(/Q)S(/T)VTSPQQ], hexapeptide (PGQGQQ), and tetrapeptide (ITVS). The 13-residue repeats were restricted to the current sequences, while the tetrapeptides were only shared by D-hordein and the current sequences. However, these sequences were not expressed as normal HMW glutenin proteins because an in-frame stop codon located in the C-termini interrupted the intact open reading frames. A phylogenetic analysis supported different origins of the P. juncea HMW glutenin sequences than that revealed by a previous study. The current sequences showed a close relationship with D-hordein but appeared to be more primitive.

Expressed Ay HMW glutenin subunit in Australian wheat cultivars indicates a positive effect on wheat quality

Out of the six HMW-GS genes, 1Ay is usually not expressed in bread wheat cultivars. In the current study, an active 1Ay gene has been integrated into two Australian wheat cultivars, Livingston and Bonnie Rock, through conventional backcross approach. Three sister lines at BC4F4 generation for each cross were obtained and underwent a series of quality testing. Results show that the active 1Ay subunit increased the amount total protein, Glutenin/Gliadin ratio and unextractable polymeric protein. The expressed 1Ay also resulted in up to 10% increase of gluten content, 5% increase of glutenin, and hence increased the HMW- to LMW-GS ratio without affecting the relative amount of other subunits. Milling yield and Flour swelling were decreased in the Livingston lines and remained mostly unchanged for Bonnie Rock. Alveograph result showed that Ay improved dough strength in Livingston and dough extensibility in Bonnie Rock. Zeleny sedimentation value was found to be higher in all three lines of Bonnie Rock but only in one of Livingston derivatives. The dough development time and peak resistance, determined on the micro Z-arm mixer were increased in most cases. Overall, the integration of Ay subunit showed significant positive effects in bread making quality.

Survey and new insights in the application of PCR‐based molecular markers for identification of HMW‐GS at the Glu‐B1 locus in durum and bread wheat

AbstractWheat, among all cereal grains, possesses unique characteristics conferred by gluten; in particular, high molecular weight glutenin subunits (HMW‐GS) are of considerable interest as they strictly relate to bread‐making quality and contribute to strengthening and stabilizing dough. Thus, the identification of allelic composition, in particular at the Glu‐B1 locus, is very important to wheat quality improvement. Several PCR‐based molecular markers to tag‐specific HMW glutenin genes encoding Bx and By subunits have been developed in recent years. This study provides a survey of the molecular markers developed for the HMW‐GS at the Glu‐B1 locus. In addition, a selection of molecular markers was tested on 31 durum and bread wheat cultivars containing the By8, By16, By9, Bx17, Bx6, Bx14 and Bx17 Glu‐B1 alleles, and a new assignation was defined for the ZSBy9_aF1/R3 molecular marker that was specific for the By20 allele. We believe the results constitute a practical guide for results that might be achieved by these molecular markers on populations and cultivars with high variability at the Glu‐B1 locus.

Comprehensive Proteomic Profiling of Wheat Gluten Using a Combination of Data-Independent and Data-Dependent Acquisition.

Wheat is the most important food crop in the world, the unique physiochemical properties of wheat gluten enabling a diverse range of food products to be manufactured. However, genetic and environmental factors affect the technological properties of gluten in unpredictable ways. Although newer proteomic methods have the potential to offer much greater levels of information, it is the older gel-based methods that remain most commonly used to identify compositional differences responsible for the variation in gluten functionality, in part due to the nature of their primary sequences. A combination of platforms were investigated for comprehensive gluten profiling: a QTOF with a data independent schema, which incorporated ion mobility (DIA-IM-MS) and a data dependent acquisition (DDA) workflow using a linear ion trap quadrupole (LTQ) instrument. In conjunction with a manually curated gluten sequence database a total of 2736 gluten peptides were identified with only 157 peptides identified by both platforms. These data showed 127 and 63 gluten protein accessions to be inferred with a minimum of one and three unique peptides respectively. Of the 63 rigorously identified proteins, 26 were gliadin species (4 ω-, 14 α-, and 8 γ-gliadins) and 37 glutenins (including 29 LMW glutenin and 8 HMW glutenins). Of the HMW glutenins, three were 1Dx type and five were 1Bx type illustrating the challenge of unambiguous identification of highly polymorphic proteins without cultivar specific gene sequences. The capacity of the platforms to sequence longer peptides was crucial to achieving the number of identifications, the combination of QTOF-LTQ technology being more important than extraction method to obtain a comprehensive profile. Widespread glutamine deamidation, a post-translational modification, was observed adding complexity to an already highly polymorphic mixture of proteins, with numerous insertions, deletions and substitutions. The data shown is the most comprehensive and detailed proteomic profile of gluten to date.

Allelic Variation and Correlation Analysis in Bread Wheat (<i>Triticum Aestivum</i> L.) Accessions Based on Various Polygenic Traits

To evaluate frequency distribution, correlation coefficient and allelic diversity of different wheat ( Triticum Aestivum L.) germplasms, an experiment was done for one hundred wheat accessions during the rabi season 2004-05 with augmented field design at experimental area of Faculty of Agriculture, Gomal University, Dera Ismail Khan, Pakistan. Data were taken for different morphological parameters i.e. spike length (cm), number of spikelets spike -1 , grain yield plant -1 , 1000-grain weight and grain yield (Kg/Ha). The frequency distribution for spike length ranged from 6.2 to 22.1 (cm) with coefficient of variation 18.63%. The variation for grain yield plant -1 ranged from 1.26 to 4.58 (g) with coefficient of variation 21.89%. 1000-grain weight (g) varied from 15.74 to 46.65 (g) with coefficient of variation 23.55%. While, frequency distribution for grain yield (Kg/Ha) ranged from 2 610 to 5 065.9 (Kg/Ha). Hence, Spike length revealed significant and highly positively correlation with number of spikelets spike -1 , grain yields plant -1 and grain yield (Kg/Ha). While, highly significant positive correlation was observed of 1000-grain weight with grain yield (Kg/Ha). In the 2 nd part of experiment, SDS-PAGE analysis was utilized to study allelic diversity for high molecular weight glutenin subunit composition in the said 100 germplasm of wheat ( Triticum Aestivum L.). All the accessions were partitioned into eighteen different HMW- glutenin subunit combinations, in which the subunit “null” (48%) has maximum frequency at the Glu-A1 locus. The most frequent HMW glutenin subunits at Glu-B1 locus were 7+8 with 54%. While, at locus Glu-D1 the subunit 2+12 was found in most of accessions with frequency of 79%. Hence in the experimental study fifteen accessions (PARC/MAFF 4272 (01), 4269 (01), 4358 (01), 4355 (02), PARC/JICA 3835 (05), PARC/MAFF 4358 (03), 4292 (01), 4354 (02), 4354 (01), 4264 (03), 4280 (03), 4269 (02), 4279 (01), 4277 (01), 4277 (02) were investigated for a desired quantitative traits with known sub units for good bread making quality, which leads to improvement in further wheat breeding programmes.

Transfer of HMW glutenin subunits from Aegilops kotschyi to wheat through radiation hybridization.

High molecular weight glutenin subunits (HMWGS) are responsible for dough elasticity and bread making quality of bread wheat. Related wild non-progenitor species, Aegilops kotschyi possesses higher molecular weight x and y glutenin subunits than the bread wheat cultivars. A wheat-Aegilops substitution line with 1U chromosome was used for the transfer of (HMWGS) of 1U to wheat by using pollen radiation hybridization approach. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiling showed different patterns of allelic variations with either the presence or absence of HMWGS, Glu-1A (1, null), Glu-1B (7, 7+8, 17+18) and Glu-1D (5+10, 2+12, null). The pollen irradiated wheat-Aegilops derivatives, B-56-1-4-2, B-56-1-4-3, B-14-1 and B-14-2 with Glu1Ux and 1Uy and absence or presence of some Glu-1A and Glu-1B HMWGS showed high micro SDS sedimentation test (MST) values while B-16-1 and B-16-2 had moderate MST values and high protein content. However, B-58-3 with transfer of Glu-1Ux+1Uy for Glu-1D showed very low MST values indicating that Glu-1Ux+1Uy enhance MST value only in the presence of Glu1D HMWGS. The transfer/substitution of alien HMW-GS for Glu-1A and or Glu-1B loci only can lead to improved bread making quality of wheat.

Advances in the regulation of HMW glutenin genes of wheat

Advances in the regulation of HMW glutenin genes of wheat

Effect of foliar application of Cu, Zn, and Mn on yield and quality indicators of winter wheat grain

Micronutrients are part of many crucial physiological plant processes. The combined application of N and micronutrients helps in obtaining grain yield with beneficial technological and consumer properties. The main micronutrients needed by cereals include Cu, Mn, and Zn. The subject of this study was to determine yield, quality indicators (protein content and composition, gluten content, grain bulk density, Zeleny sedimentation index, and grain hardness), as well as mineral content (Cu, Zn, Mn, Fe) in winter wheat grain (Triticum aestivum L.) fertilized by foliar micronutrient application. A field experiment was carried out at the Educational and Experimental Station in Tomaszkowo, Poland. The application of mineral fertilizers (NPK) supplemented with Cu increased Cu content (13.0%) and ω, α/β, and γ (18.7%, 4.9%, and 3.4%, respectively) gliadins in wheat grain. Foliar Zn fertilization combined with NPK increased Cu content (14.9%) as well as high (HMW) and low molecular weight (LMW) glutenins (38.8% and 6.7%, respectively). Zinc fertilization significantly reduced monomeric gliadin content and increased polymeric glutenin content in grain, which contributed in reducing the gliadin:glutenin ratio (0.77). Mineral fertilizers supplemented with Mn increased Fe content in wheat grain (14.3%). It also significantly increased protein (3.8%) and gluten (4.4%) content, Zeleny sedimentation index (12.4%), and grain hardness (18.5%). Foliar Mn fertilization increased the content of ω, α/β, and γ gliadin fractions (19.9%, 9.5%, and 2.1%, respectively), as well as HMW and LMW glutenins (18.9% and 4.5%, respectively). Mineral NPK fertilization, combined with micronutrients (Cu + Zn + Mn), increased Cu and Zn content in grain (22.6% and 17.7%, respectively). The content of ω, α/β, and γ gliadins increased (20.3%, 10.5%, and 12.1%, respectively) as well as HMW glutenins (7.9%).

Ancient DNA from 8400 Year-Old Çatalhöyük Wheat: Implications for the Origin of Neolithic Agriculture.

Human history was transformed with the advent of agriculture in the Fertile Crescent with wheat as one of the founding crops. Although the Fertile Crescent is renowned as the center of wheat domestication, archaeological studies have shown the crucial involvement of Çatalhöyük in this process. This site first gained attention during the 1961–65 excavations due to the recovery of primitive hexaploid wheat. However, despite the seeds being well preserved, a detailed archaeobotanical description of the samples is missing. In this article, we report on the DNA isolation, amplification and sequencing of ancient DNA of charred wheat grains from Çatalhöyük and other Turkish archaeological sites and the comparison of these wheat grains with contemporary wheat species including T. monococcum, T. dicoccum, T. dicoccoides, T. durum and T. aestivum at HMW glutenin protein loci. These ancient samples represent the oldest wheat sample sequenced to date and the first ancient wheat sample from the Middle East. Remarkably, the sequence analysis of the short DNA fragments preserved in seeds that are approximately 8400 years old showed that the Çatalhöyük wheat stock contained hexaploid wheat, which is similar to contemporary hexaploid wheat species including both naked (T. aestivum) and hulled (T. spelta) wheat. This suggests an early transitory state of hexaploid wheat agriculture from the Fertile Crescent towards Europe spanning present-day Turkey.

Effect of Climate Change on Wheat Quality and HMW Glutenin Subunit Composition in the Pannonian Plain

The primary goal of this study is to improve our understanding of the extent of influence of climatic factors in Serbia and high‐molecular‐weight glutenin subunit (HMW‐GS) composition upon wheat end‐use quality. In‐depth analyses were performed on four bread wheat cultivars that are the most common in agricultural practice in Serbia. Total glutenin content showed significant difference between the production years, in opposition to gliadins. Cluster analysis of different percentages of glutenin and gliadin subunit molecular weight ranges (<40,000, 40,000–80,000, 81,000–120,000, and >120,000) indicated that the year of production and the cultivar did not have a significant effect on the percentage ranges for glutenins. However, they had a considerable impact on the percentage ranges for gliadins. Production year and the interaction of year and cultivar had the strongest influences on the percentage of SDS‐unextractable polymeric proteins. A synergistic effect of the HMW‐GS composition and climatic conditions revealed that all eight samples with HMW‐GS composition 2*, 5 + 10, 7 + 9 along with the highest Glu 1 score of 9 (out of a maximum of 10) produced in the year 2011 belonged to two clusters with the best wheat end‐use quality. Furthermore, the climate conditions in 2011 made it possible for the wheat cultivars with HMW‐GS composition –, 2 + 12, 7 + 9 to possess similar qualities as cultivars with HMW‐GS composition 2*, 5 + 10, 7 + 9 produced in 2012.

Molecular characterization and marker development for hexaploid wheat-specific HMW glutenin subunit 1By18 gene

Wheat grain high molecular weight glutenin subunits (HMW-GS) are the major determinants of dough elasticity and viscosity, and thus of breadmaking quality. Most known HMW-GS genes in bread wheat have been already cloned except for very few such as 1By18 and 1By19. In this study, HMW-GS 1By18 gene was isolated from bread wheat for the first time. In the past, this subunit has been considered to have positive effect on gluten quality. Molecular characterization of the 1By18 subunit gene showed that its complete coding nucleotide sequence was 2163 bp long, being highly identical to 1By8, with only three single nucleotide polymorphisms (SNPs) at sites 231, 233 and 1976 of the coding sequence. The deduced amino acid sequence of 1By18 exhibited two substitutions compared to 1By8. The deduced protein was further verified by expression in E. coli and LC–MS/MS analysis. Phylogenetic analysis showed that 1By18 was more closely related to 1By8, 1By9 and 1By16 than to 1By15 and 1By20. Molecular phylogenetic analysis indicated that the Glu-B1i allele emerged after the formation of modern hexaploid wheat. Two sets of SNP-based AS-PCR markers for 1By18 gene were developed and validated on 110 bread wheat varieties with different Glu-Bly alleles, and five recombinant inbred lines. Both markers could effectively distinguish 1By18 from the other genes at the Glu-B1 locus, thus making them valuable for marker-assisted selection in wheat quality improvement programs.

Targeting of prolamins by RNAi in bread wheat: effectiveness of seven silencing-fragment combinations for obtaining lines devoid of coeliac disease epitopes from highly immunogenic gliadins.

Gluten proteins are responsible for the viscoelastic properties of wheat flour but also for triggering pathologies in susceptible individuals, of which coeliac disease (CD) and noncoeliac gluten sensitivity may affect up to 8% of the population. The only effective treatment for affected persons is a strict gluten-free diet. Here, we report the effectiveness of seven plasmid combinations, encompassing RNAi fragments from α-, γ-, ω-gliadins, and LMW glutenin subunits, for silencing the expression of different prolamin fractions. Silencing patterns of transgenic lines were analysed by gel electrophoresis, RP-HPLC and mass spectrometry (LC-MS/MS), whereas gluten immunogenicity was assayed by an anti-gliadin 33-mer monoclonal antibody (moAb). Plasmid combinations 1 and 2 downregulated only γ- and α-gliadins, respectively. Four plasmid combinations were highly effective in the silencing of ω-gliadins and γ-gliadins, and three of these also silenced α-gliadins. HMW glutenins were upregulated in all but one plasmid combination, while LMW glutenins were downregulated in three plasmid combinations. Total protein and starch contents were unaffected regardless of the plasmid combination used. Six plasmid combinations provided strong reduction in the gluten content as measured by moAb and for two combinations, this reduction was higher than 90% in comparison with the wild type. CD epitope analysis in peptides identified in LC-MS/MS showed that lines from three plasmid combinations were totally devoid of CD epitopes from the highly immunogenic α- and ω-gliadins. Our findings raise the prospect of breeding wheat species with low levels of harmful gluten, and of achieving the important goal of developing nontoxic wheat cultivars.

Allelic diversity of HMW and LMW glutenins in Indian wheats and their relationship with sedimentation volume and mixograph parameters

Two hundred and forty diverse set of wheat cultivars released in India during the last several decades were evaluated for HMW and LMW glutenin alleles, for assessing their diversity and effect on sedimentation volume and mixograph parameters. Both SDS-PAGE and PCR based markers were employed in identifying alleles encoded at Glu-1 and Glu-3 loci. Extensive allelic variation was observed at both the Glu-1 and Glu-3 loci. There was prevalence of Glu-A1b, Glu-B1i, Glu-D1a, Glu-A3c, Glu-B3b, Glu-B3g and Glu-D3b. The alleles Glu-A1b, Glu-B1i, Glu-D1d, Glu-A3b, Glu-B3g/h and Glu-D3b exhibited high SDS-sedimentation volume. Glu-B1i and Glu-D1d showed highly significant positive effect (p < 0.001) on sedimentation volume and also had additive effects. However, surprisingly overall there was decline in the frequency of Glu-B1i allele during last two decades in Indian wheat breeding and not a single 1B/1R translocation cultivar possessed this allele. Glu-A1b showed significant positive effect on mixograph peak time, peak slope and peak width. Glu-B3g exhibited significantly higher mixograph peak time and width at 8 and Glu-B3h showed higher dough stability. Glu-B3j (1B/1R translocation) exhibited highest peak slope indicating the negative effect on dough strength. This information can be useful in designing breeding program for the improvement of Indian bread wheat quality.

Benefits and Limitations of Lab-on-a-Chip Method over Reversed-Phase High-Performance Liquid Chromatography Method in Gluten Proteins Evaluation

RP-HPLC (reversed-phase high-performance liquid chromatography) is widely used to determine the amounts of the different gluten protein types. However, this method is time-consuming, especially at early stages of wheat breeding, when large number of samples needs to be analyzed. On the other hand, LoaC (Lab-on-a-Chip) technique has the potential for a fast, reliable, and automatable analysis of proteins. In the present study, benefits and limitations of Lab-on-a-Chip method over RP-HPLC method in gluten proteins evaluation were explored in order to determine in which way LoaC method should be improved in order to make its results more compliant with the results of RP-HPLC method. Strong correlation (P≤0.001) was found between numbers of HMW glutenin peaks determined by LoaC and RP-HPLC methods. Significant correlations (P≤0.05) were obtained between percentages of HMW and LMW glutenin subunits calculated with regard to total HMW + LMW area. Even more significant correlation (P≤0.001) was found when percentages of individual HMW areas were calculated with regard to total HMW. RP-HPLC method showed superiority in determination of gliadins since larger number and better resolution of gliadin peaks were obtained by this method.

Molecular characterization and phylogenetic analysis of unusual x-type HMW glutenin subunits from 1sl genome of Aegilops longissima

Wheat related diploid species Ae. longissima (2n=2x=14, SlSl) has extensive storage protein variations that may provide useful gene resources for wheat quality improvement. In this work, five novel 1Sl-encoded x-type high molecular glutenin subunits (HMW-GS) were identified and designated as 1Slx-123, 1Slx-129, 1Slx1-136, 1Slx2-136 and 1Slx2.2, respectively. Their complete open reading frames (ORFs) were cloned and sequenced by AS-PCR, which contained 2874 bp (956 aa) for 1Slx-123, 2946 bp (979 aa) for 1Slx-129, 2901 bp (965 aa) for 1Slx1-136, 2982bp (991 aa) for 1Slx2-136 and 2928 bp (974 aa) for 1Slx2.2. Molecular characterization demonstrated that five unusual subunits had greater repetitive domains resulted from a larger fragment insertion (74-113 aa). Particularly, 1Slx-129 had an extra cysteine residue at the position 109 due to a TAT ? TGT dot mutation, which may improve the formation of superior gluten macropolymer. Our results suggest that these unusual HMW-GS could be served as potential superior gene resources for improving wheat gluten quality. Phylogenetic analysis revealed that HMW-GS genes from Glu-1Sx genomes had close evolutionary relationships with those of Glu-1Dx genome while sequences from Ae. speltoides aligned with those of B genome.

Changes in bread-making quality attributes of bread wheat varieties cultivated in Spain during the 20th century

Genetic gains in quality traits were assessed in grain samples from 4 field experiments involving 16 bread wheat varieties representative of those most widely cultivated in Spain during the 20th century. The allelic composition at three glutenin loci (Glu-A1, Glu-B1, and Glu-D1) was obtained by PCR-based DNA markers and published references. From 1930 to 2000 grain protein content decreased by −0.030%y−1, or in relative terms by −0.21%y−1, but the protein produced per hectare increased by 0.39%y−1. Alveographic tests revealed significant changes in dough rheological properties. Dough strength (W) and tenacity (P) increased at relative rates of 1.38%y−1 and 0.99%y−1, respectively, while dough extensibility (L) decreased by −0.46%y−1, resulting in an increase of 1.45%y−1in dough equilibrium (P/L). The rise in protein quality could be related to the replacement of the null allele by subunits 1 or 2* at Glu-A1 and the prevalence of subunits 7+8 and 5+10 at Glu-B1 and Glu-D1 loci, respectively, in the most recent varieties. Dough extensibility was affected by water input during the crop cycle, this relationship being partially explained by the presence of the 5+10 HMW glutenin subunit. Fermentation tolerance was improved in the most modern varieties. Collapse during fermentation was avoided only in doughs with a W≥159 J×10−4 and a P/L≥0.56mm H2O mm−1, levels achieved by most of the modern varieties. The over-strong and unbalanced rheological properties of some modern varieties resulted in highly porous doughs, and no clear advances in dough maximum height during fermentation were attained.