Sodium Dodecyl Sulfate Sedimentation Research Articles

Response to heat stress and glutenins allelic variation effects on quality traits in durum wheat

AbstractIn the context of climate change, high temperature is one of the main abiotic stresses hampering durum wheat production. Through the characterization of an international panel of 271 genotypes, this study investigates the effects of heat stress on quality traits and identifies which glutenins (Glu‐1, Glu‐2 and Glu‐3 loci) alleles are the most important to obtain high gluten strength under optimal and high temperature conditions. In parallel with the wide variability observed in the panel, the genotype and environmental effects, including their interaction, showed highly significant effect on test weight, thousand kernel weight, grain protein content (GPC), sodium dodecyl sulphate sedimentation volume (SDSS) and SDSS index. Only one genotype maintained test weight and thousand kernel weight under heat‐stress conditions whereas for GPC, SDSS and SDSS index, most genotypes increased values. All Glu loci had significant effects on grain protein content (with the exception of Glu‐B2), SDSS and SDSS Index. None of the Glu loci interacted with the environment or years under study. Among the identified alleles, Glu‐A1b, Glu‐B1an, Glu‐B1a, Glu‐B2a, Glu‐A3a.x, Glu‐A3d, Glu‐B3a and Glu‐B3ax (including the LMW‐2 pattern) were associated with high values for SDSS and SDSS Index. Genotypes identified in this study, with good performances under optimal and high temperature growing conditions, could be useful for breeding programs. The non‐interaction of the Glu loci with the environment facilitates the introgression of desired alleles regardless of high growing temperatures.

Determining factors of durum wheat bread loaf volume and alveograph characteristics under optimal, drought and heat stress conditions

Durum wheat is an important crop, especially in Mediterrannean countries; around 25% of durum wheat world-wide, and 70–90% in the Middle East, is used for bread making. Climate change is causing increased periods of drought stress and higher temperatures which are affecting wheat quality. Alveograph extensibility is important for durum wheat loaf volume (LFV), as is the relationship between dough tenacity and extensibility. This study was done to identify the factors determining LFV and alveograph properties under optimal and stress conditions. Six durum wheat cultivars with the same glutenin composition were grown for two seasons under optimal, drought and heat stress conditions. Good LFV was consistently related with higher dough extensibility, irrespective of production conditions. A number of the LMW glutenin fractions, and the γ-gliadins were significantly reduced and β-gliadins were increased under both heat and drought stress. The large and total unextractable polymeric proteins and unextractable HMW glutenins were significantly reduced by heat stress. In a multiple regression of LFV (without alveograph values), solvent retention capacity and sodium dodecyl sulphate sedimentation were the best predictors of LFV under all conditions. Size-exclusion high-performance liquid chromatography fractions combined with flour protein content were good predictors of LFV only under optimal conditions.

Association of High and Low Molecular Weight Glutenin Subunits with Gluten Strength in Tetraploid Durum Wheat (Triticum turgidum spp. Durum L.)

The gluten strength and the composition of high- and low-molecular-weight glutenin subunits (HMWGSs and LMWGSs) of fifty-one durum wheat genotypes were evaluated using sodium dodecyl sulfate (SDS) sedimentation testing and SDS polyacrylamide gel electrophoresis (SDS-PAGE). This study examined the allelic variability and the composition of HMWGSs and LMWGSs in T. durum wheat genotypes. SDS-PAGE was proven to be a successful method for identifying HMWGS and LMWGS alleles and their importance in determining the dough quality. The evaluated durum wheat genotypes with HMWGS alleles 7+8, 7+9, 13+16, and 17+18 were highly correlated with improved dough strength. The genotypes containing the LMW-2 allele displayed stronger gluten than those with the LMW-1 allele. The comparative in silico analysis indicated that Glu-A1, Glu-B1, and Glu-B3 possessed a typical primary structure. The study also revealed that the lower content of glutamine, proline, glycine, and tyrosineand the higher content of serine and valine in the Glu-A1 and Glu-B1 glutenin subunits, and the higher cysteine residues in Glu-B1 and lower arginine, isoleucine, and leucine in the Glu-B3 glutenin, are associated with the suitability of durum wheat for pasta making and the suitability of bread wheat with good bread-making quality. The phylogeny analysis reported that both Glu-B1 and Glu-B3 had a closer evolutionary relationship in bread and durum wheat, while the Glu-A1 was highly distinct. The results of the current research may help breeders to manage the quality of durum wheat genotypes by exploiting the allelic variation in glutenin. Computational analysis showed the presence of higher proportions of glutamine, glycine, proline, serine, and tyrosine than the other residues in both HMWGSs and LMWGSs. Thus, durum wheat genotype selection according to the presence of a few protein components effectively distinguishes the strongest from the weakest types of gluten.

Grain and flour characteristics of eastern U.S. soft winter wheat desirable for making soft‐bite white salted noodles

AbstractBackground And ObjectivesThe genetic backgrounds and growing conditions of eastern U.S. soft winter (ESW) wheat vary widely and thus produce grains of diverse quality characteristics, which encompass those required for making soft‐bite white salted noodles (WSN). However, these characteristics have yet to be identified and cataloged. The grain and flour characteristics and WSN making quality of 25 ESW wheat varieties and four commercial noodle flours (CNFs) were analyzed to identify grain and flour characteristics desirable for making WSN.FindingsKernel hardness, protein content, and gluten strength‐related parameters of ESW wheat were significantly associated with WSN cooking and textural properties, while damaged starch content was the major determinant of WSN adhesiveness. A total of 9 out of 25 ESW wheat flours exhibited protein characteristics, WSN color and textural properties that closely matched to those of CNFs.ConclusionsESW wheat varieties with kernel hardness of 16.0–45.4, damaged starch content of 1.9%–4.4%, flour protein content of 8.6%–10.2%, sodium dodecyl sulfate sedimentation volume of 30.4–41.6 ml and lactic acid solvent retention capacity of 115.6%–142.7% were identified to produce WSN of comparable quality to those of CNFs.

Effect of Sitophilus zeamais (Coleoptera: Curculionidae) Infestation on the Protein Physicochemical and Structural Properties of Wheat Grain.

Boring pests such as Sitophilus zeamais (S. zeamais) are major threats in grain storage. However, how these pests affect the proteins of stored grains remains largely unknown. Here we aimed to investigate the effect of S. zeamais infestation on wheat protein during postharvest storage. In this study, wheat grain infested by S. zeamais was sampled at egg (4 d), larval (20 d), pupal (35 d), and adult stages (45 d), respectively. The protein's physicochemical and structural properties and the edible quality of whole wheat noodle were analyzed. The results showed that S. zeamais infestation significantly decreased the quality of wheat protein by altering its constitution and structure properties. Especially, compared with the control, the content of wet and dry gluten, gluten index, sodium dodecyl sulfate sedimentation volume, sulfhydryl groups, and disulfide bonds in insect-infested wheat decreased by 19.40, 5.42, 18.40, 8.12, 29.13, and 14.30%, respectively, during the storage period of one life cycle of S. zeamais. Additionally, the proportions of wheat protein fractions (albumin [1.16-fold], globulin [0.96-fold], gliadin [1.16-fold], and glutenin [0.95-fold]) and secondary structures (α-helix [0.91-fold], β-fold [0.96-fold], β-turn [1.06-fold], and random coil [1.05-fold]) of protein changed significantly, and the gluten network structure was broken in S. zeamais-infested wheat. Furthermore, the color of whole wheat noodle became darker, cooking loss rate increased, and textural properties (hardness, adhesiveness, springiness, cohesiveness, chewiness, and resilience) decreased as well. The results in the present study provided new insights for analyzing the quality deterioration mechanism and further quality improvement of boring pests-infested wheat grain.

Increasing grain yield while maintaining baking quality in Canada Western Red Spring wheat

Grain protein concentration (GPC) is considered one of the most important quality factors, and it has remained a major culling criterion in the Canadian wheat cultivar development and registration process. However, grain protein composition also plays a critical role in determining the end-use quality of cereal-based products. The objective of this study was to determine whether high-yielding, lower protein Canada Western Red Spring (CWRS) analog wheat lines can exhibit acceptable baking properties (comparable with CWRS cultivars) under contrasting soil nitrogen levels. Five CWRS-analog lines together with four CWRS and one Canada Prairie Spring Red wheat cultivar, representing wide ranges of quality and grain yield potential, were assessed for agronomic and quality traits in multi-environment trials at three locations and five nitrogen fertilizer rates. CWRS analog lines produced significantly higher grain yield and, on average, 0.9% less GPC than the CWRS cultivars. Despite the lower GPC, CWRS-analog lines such as W07786 exhibited suitable and stable baking performance across all nitrogen levels. Based on the genotype × trait biplot analysis, CWRS-analog baking properties were mainly associated with sodium dodecyl sulfate sedimentation and flour water absorption. Our findings revealed that it is possible to develop wheat cultivars with up to 15% higher grain yield than modern CWRS cultivars and comparable end-use characteristics by reducing current GPC requirements (by up to 1%) while simultaneously selecting for improved baking attributes. This would facilitate an increase in CWRS grain yield genetic gains while maintaining favorable end-use quality and improving the crop competitiveness in western Canada.

Quality analysis of all‐purpose wheat flour pasteurized with radiofrequency‐assisted hot air heating

AbstractRadiofrequency (RF) is a promising technology for preheating wheat flour for pasteurization but may influence its quality and functional properties. This study evaluated the quality and functionality change of bleached and unbleached, all‐purpose wheat flours after treating with RF and/or extended hot air heating at three processing temperatures (80, 85, and 90°C). The moisture content, color, sodium dodecyl sulfate (SDS) sedimentation test, flour swelling power, and solvent retention capacity (SRC) tests were measured. The moisture content of both bleached and unbleached samples decreased after the RF treatment, and the extended hot air heating further increased the moisture loss. The ΔE values of color change were less than two for all processing conditions, indicating little color change. The SDS results showed that the sedimentation volumes decreased after the thermal treatments, indicating decreased relative gluten strength. The flour swelling power increased after the RF and the extended hot air heating. The SRC tests measured the flour retention in four different solvents of 5% lactic acid, 5% sodium carbonate, 50% sucrose, and water, and their values were within the reported ranges of a variety of flour samples. The gluten performance index calculated from the four SRC values decreased after RF and extended hot air heating. The results showed that most heating conditions significantly changed the overall quality of flour samples, statistically (p < 0.05). However, the absolute changes of the values were small and within ranges of the reported values. Thus, the RF‐assisted pasteurization may not influence the practical applications of the treated flour for different flour‐based products.Practical ApplicationRF is a promising technology for preheating flour for pasteurization. The study found that the RF‐treated all‐purpose flours showed significant quality and functional properties change, statistically, but the absolute changes of the properties were small and within ranges of the reported values. Thus, RF heating and extended hot air heating can be used to pasteurize wheat flours without influencing their practical application.

Gluten and starch mixing and pasting behaviour as affected by replacing sodium chloride with sodium replacers in wheat flour dough

SummaryThe study focused on analysing the effect of sodium replacers (KCl, MgCl2, MgSO4, CaCl2 and K‐gluconate) at 1% and 2% concentration on thermo‐mechanical properties (water absorption, dough development time, protein weakening, breakdown and retrogradation) of wheat flour evaluated using Mixolab. Blends of NaCl and sodium replacers (ratio 1:1) at 2% concentration were also studied. Water absorption and peak viscosity decreased, whereas dough stability increased on replacing sodium with different sodium replacer salts. Addition of salts did not affect shear thinning or starch breakdown behaviour during pasting. Salts and their blends lowered SDS (Sodium dodecyl sulphate) sedimentation value of wheat flour indicating that SDS sedimentation values significantly positively correlated with water absorption (r = 0.70, P < 0.05), protein weakening C2 (r = 0.61, P < 0.05) and peak viscosity C3 (r = 0.62, P < 0.05). In general, KCl behaved most similar to NaCl. Thermo‐mechanical properties of wheat dough did not differ between NaCl and majority of the salts evaluated.

통밀빵 제조에 적합한 통밀가루 품질지표 규명

Purpose: This study was to identify the major quality parameters of whole wheat flour suitable for making whole wheat bread. Methods: The commercial twelve whole wheat flour samples were analyzed for physicochemical characteristics and bread-baking performance. Results: The tested samples showed a wide range of ash contents, water, sodium carbonate solvent retention capacity (SRC), sodium dodecyl sulfate (SDS)-sedimentation volumes, particle sizes, and colors. The bread-making performance of the flours also showed significant variations in crumb colors, dough heights, bread heights, and bread volumes. The correlation and principal component analyses of the quality characteristics of whole wheat flour and whole wheat bread showed that the dough height and the bread height and volume correlated negatively with the ash content and water SRC but positively with the SDS sedimentation of the whole wheat flour. However, the firmness of the bread showed the opposite relationship. Conclusion: In conclusion, the ash content, water SRC, and SDS sedimentation volume of the whole wheat flour can be used as valuable indicators to predict the quality of the whole wheat bread.

Characterization of 1Sty13, a novel high-molecular-weight glutenin subunit from Elymus sibiricus L.

AbstractHigh-molecular-weight glutenin subunit (HMW-GS) is a key factor affecting dough-processing quality. 1Sty13 is a novel HMW-GS found in the tetraploid species, Elymus sibiricus L. 1Sty13 has faster electrophoretic mobility than the 1Dy12 subunit on sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis. The gene encoding the 1Sty13 subunit was composed of 1803 nucleotide base pairs with an open reading frame that was 599 amino acids in length. Analysis of the predicted amino acid sequence of 1Sty13 indicated that the N-terminal domain was similar to the y-type subunit, whereas the C-terminal domains were similar to the x-type subunit. Five cysteine residues were found in 1Sty13, which is one less than the published HMW-GS in the St genome. The 1Sty13 protein was purified at a scale sufficient for incorporation into flour for the SDS sedimentation test, which indicated that incorporating 1Sty13 improved dough quality.

Solvent Retention Capacity and Gluten Protein Composition of Durum Wheat Flour as Influenced by Drought and Heat Stress.

Drought and temperature stress can cause considerable gluten protein accumulation changes during grain-filling, resulting in variations in wheat quality. The contribution of functional polymeric components of flour to its overall functionality and quality can be measured using solvent retention capacity (SRC). The aim of this study was to determine the effect of moderate and severe drought and heat stress on SRC and swelling index of glutenin (SIG) in six durum wheat cultivars with the same glutenin subunit composition and its relation with gluten protein fractions from size exclusion high performance liquid chromatography. Distilled water, sodium carbonate and sucrose SRC reacted similarly to stress conditions, with moderate heat causing the lowest values. Lactic acid SRC and SIG reacted similarly, where severe heat stress highly significantly increased the values. SIG was significantly correlated with sodium dodecyl sulphate sedimentation (SDSS) and flour protein content (FPC) under all conditions. Lactic acid SRC was highly correlated with FPC under optimal and moderate heat stress and with SDSS under moderate drought and severe heat. SIG was negatively correlated with low molecular weight glutenins under optimal and drought conditions, and combined for all treatments. The relationship between SRC and gluten proteins was inconsistent under different stress conditions.

Bread-making properties of einkorn wheat (Triticum monococcum ssp. monococcoum) and its suitability for whole wheat bread production

With the increase in demand for healthy and safe food, the interest in the wild ancestors of wheat and the demand for einkorn wheat have increased in the last few decades. In Turkey, einkorn wheat is commonly consumed as bulgur. However, due to the higher protein, minerals particularly Zn and Fe, and phenolic compounds it contains, einkorn wheat flour has started to be added to wheat flour at different rates. Aim in this study is to determine the suitability of einkorn wheat for bread making. Einkorn refined flour addition enables lighter and brighter bread production, while the increasing amount of whole wheat flour has brought together darker bread. Due to the higher amount of bran, it contains, whole wheat flour has led to a significant reduction in bread volume value. The ZS, modified Zeleny sedimentation, SDSS and modified sodium dodecyl Sulphate sedimentation values which directly affect the bread structure showed significant decreases as the amount of einkorn flour and wholemeal flour increased. Einkorn can be mixed with bread wheat flour and whole wheat flour in certain proportions and used in the production of bread suitable for consumer demands. Although it causes a certain decrease in bread structure; einkorn has enough potential to be used in making both wheat bread and whole wheat bread.

Diversity in Grain, Flour, Amino Acid Composition, Protein Profiling, and Proportion of Total Flour Proteins of Different Wheat Cultivars of North India.

Wheat cultivars grown at three different locations in North India were assessed for their variability in kernel and flour characteristics. Protein and the wet and dry gluten contents of the flour varied significantly (p ≤ 0.05) from 9.32 to 12.60%, 23.46 to 43.04%, and from 8.28 to 15.00%, respectively. Wheat varieties exhibited moderate sodium dodecyl sulfate (SDS) sedimentation and solvent retention values. Flour showed a significant (p ≤ 0.05) difference in the amino acid composition. Lysine, having the lowest chemical score, was the first most limiting amino acid in all wheat varieties. The variability of total flour proteins determined by SDS-PAGE showed polymorphism both in the number and intensity of bands, particularly in the molecular weight range of 35.1–42.8 kDa corresponding to the α-, β-, and γ-gliadin/low-molecular-weight glutenin subunit (LMW-GS) region. Pearson's correlation established between the various grain and flour parameters showed a significant correlation, which can result in better end product use.

Changes in yield determinants and quality traits in wheat after 12 cycles of recurrent selection

The objective of this study was to test the genetic response to 12 cycles of a recurrent selection program for grain yield and related traits. During two seasons the 39 S-derived families (three/C0–C12 populations) were evaluated under conventional (CT) and non-tillage (NT) systems. Grain and biomass yield were determined. The grain number per square meter and harvest index were also estimated. Flour protein content, sodium dodecyl sulphate sedimentation, and lactic acid solvent retention capacity were considered as end-use quality predictive tests. High molecular weight glutenin subunits (HMW-GS) variation was also analyzed. A significant increase in grain yield per selection cycle, estimated in 3.25 g m−2 (1.3%) per year, was found under NT, but there was a not significant genetic progress under CT. The decrease in the percentage of protein in the most advanced selection cycles (11.0% vs. 9.7%) did not negatively affect its quality. HMW-GS variation analysis showed the erosion of extreme subunits related to gluten strength. After 24 years of recurrent selection, the grain yield was improved without affecting its industrial quality.

Grain yield, nitrogen use efficiency and tillage intensity in wheat as affected by precision nutrient management

ABSTRACT The present studies were conducted to evaluate the effect of different nutrient management practices under two tillage options in wheat. The experiments were laid out in split-plot design with a combination of two varieties (WH 1105 and HD 2967) and two tillage options (Conventional and No tillage) in the main plot and six precision nutrient management practices [absolute control, site-specific nutrient management with Nutrient Expert for wheat (SSNM-NE)(170 kg nitrogen (N)/ha), SSNM NE+GreenSeeker (GS)(153/158 N kg/ha), N120 (120 kg N/ha) before irrigation, N120 after irrigation and N Rich (180 kg N/ha)] in subplot replicated thrice. The grain yield and quality characters in no tillage (NT) and conventional tillage (CT) were similar but agronomic efficiency was higher in NT. Both the varieties (WH 1105 and HD 2967) gave similar grain yield and quality. Wheat variety WH 1105 recorded significantly higher sodium dodecyl sulfate sedimentation (SDS) and gluten index. The treatment SSNM NE+GS had resulted in 107.1% higher grain yield than no nitrogen control but similar to enriched N plot (180 kg N/ha). The grain protein, SDS and gluten index in need-based nutrient management (SSNM+GS) treatment were found to be similar as recorded in SSNM-NE (170 kgN/ha) and N enriched plot (180 kg N ha−1). The agronomic efficiency and recovery efficiency in SSNM+GS were also better than SSNM NE.

Morpho-physiological and qualitative variation of domesticated einkorn (Triticum monococcum L. ssp. monococcum)

A pool of 158 Triticum monococcum L. ssp. monococcum accessions, originating from different traditional cropping areas and representative of the einkorn germplasm collection maintained at Sant’Angelo Lodigiano, was characterised for 20 morpho-physiological and qualitative descriptors. The accessions were grown for 4 years in two different Po plain (Italy) locations. The traits analysed were growth habit, awn length, glume colour and hairiness, rachis brittleness, heading date, plant height, spike length, n° spikelets/spike, spikelet density, n° kernels/spikelet, kernel length, width, thickness and volume, thousand kernels weight, protein and carotenoid content, sodium dodecyl sulphate sedimentation volume and specific sedimentation volume. A broad variation for all the traits studied was detected and promising accessions for breeding purposes were identified. Several characteristics showed a clear region-specific pattern: the samples tracing their origin to warmer climates were earlier-maturing, taller, had shorter spikes, fewer spikelet/spike, bigger kernels and lower protein content than those from cooler regions. A Principal Components Analysis highlighted the existence of two clusters composed mainly of Maghreb/Iberia and of Prealpine genotypes, whose peculiar characteristics are most likely a consequence of adaptation, by natural selection or by human practices and ingenuity, to their growing environments.

Allelic Variation for Prolamins in Spanish Durum Wheat Landraces and Its Relationship with Quality Traits

Wheat landraces are currently being explored mainly as a source of allelic variation related to crop resilience and low-input adaptation. Characterization of their high- and low-molecular weight glutenin subunits can aid breeders to select as donor local materials those ensuring good end-use properties in the derived elite cultivars. By using protein electrophoretic methods, we have determined the prolamin allelic profile of 116 Spanish durum wheat landraces. Their quality properties (as defined by grain protein content, sodium dodecyl sulfate (SDS) sedimentation volume and mixograph behavior) have also been assessed. The study has identified six novel glutenin alleles plus some other rare alleles some of which have been associated with improved durum wheat quality. Most of the novel variation detected needs to be characterized in a wider sample of varieties to establish any eventual beneficial effect on functional quality. Further analysis of the quality properties associated to specific allele combinations of Glu-A3, Glu-B3, and Glu-A1 has disclosed some clues on the influence on quality of certain non-allelic interactions between these main prolamin-encoding loci. Some of the landraces, showing outstanding values for the gluten quality parameters analyzed, might be directly used by farmers interested in the cultivation of traditional varieties for specialized food markets.

STUDYING GENETIC RESOURCES OF SPRING BREAD WHEAT IN THE ENVIRONMENTS OF NORTHERN KAZAKHSTAN

Background. Spring bread wheat is the main export crop in Kazakhstan. Unfortunately, wheat varieties cultivated for large-scale production do not fully meet the requirements of agricultural producers. The world diversity of wheat genetic resources should be widely used in breeding programs in order to develop new wheat cultivars with stable yields and with resistance to adverse environmental factors.Materials and methods. One hundred collection accessions of spring bread wheat were studied in 2015–2017 at the A.I. Barayev Science and Production Center of Grain Farming, Ltd. Seeds were sown at an optimum time (May 20–25), using an SSFC-7 seeder. Harvesting was conducted with a Wintersteiger combine. The study of the collection material was carried out in accordance with the guidelines developed by the N.I. Vavilov Institute of Plant Genetic Resources (VIR). The protein content was measured in line with State Standard 10846-91. The method of sodium dodecyl sulfate (SDS) sedimentation, modified by V. M. Bebyakin and M. V. Buntina, was used to measure the level of sedimentation.Results and conclusion. During the three-year study of spring bread wheat accessions in Northern Kazakhstan, only the cultivars ‘Shortandinskaya 2012’ and ‘Astana 2’ exceeded the reference ‘Astana’ in yield. The accessions ‘BW 252’, ‘Neepawa’ (Canada), ‘MANITUOU LR 13’ (CIMMYT, Mexico) and ‘Novosibirskaya 29’ (Russia) ripened 1–2 days earlier than the reference, while their average yield for 3 years was almost on the same level with the reference. The cultivars ‘Astana’ (the reference, Kazakhstan), ‘WA007824 WA7824’ (USA), ‘Novosibirskaya 29’, ‘Novosibirskaya 15’ (Russia), ‘OPATA85 LR10’ and ‘LR27+LR31,LR34’ (CIMMYT, Mexico) were distinguished for grain quality due to their high protein content and the level of sedimentation.

Change in physicochemical characteristics and molecular weight distribution of glutenin macropolymer induced by postharvest wheat maturation

The present study was aimed to investigate change in physicochemical characteristics and glutenin macropolymer (GMP) molecular weight distribution during postharvest wheat maturation. The freshly harvested wheat was stored under four different conditions (WT1, WT2, WT3 and WT4) for specified times. During maturation, the strengthening of wheat gluten structure was observed by increase in gluten index, swelling index of glutenin and sodium dodecyl sulphate (SDS) sedimentation value. The postharvest maturation resulted in contents increase of glutenin, glutenin/gliadin ratio, and GMP, and the decline of gliadin content. The contents of free sulfhydryl in GMP reduced, and S-S content rose during the whole maturation. Visible aggregates of GMP were observed in SDS-PAGE patterns for WT3 and WT4 samples after 4 weeks of storage. Moreover, in these two samples, polymerisation of gluten proteins into GMP was observed in size-exclusion high performance liquid chromatography patterns during storage. Some low molecular weight glutenin subunits (LMW-GS) incorporated into the aggregate, or combination of high molecular weight glutenin subunits and LMW-GS formed large polymeric glutenins by S-S linkage, and then assembled into GMP in postharvest wheat maturation. GMP polymerisation probably results in the improvement of wheat quality.

Effectiveness of Genomic Selection by Response to Selection for Winter Wheat Variety Improvement.

Prediction performance for winter wheat grain yield and end-use quality traits. Prediction accuracies evaluated by cross-validations are significantly overestimated. Nonparametric algorithms outperform the parametric alternatives in cross-year predictions. Strategically designing training population improves response to selection. Response to selection varies across growing seasons and environments. Considering the practicality of applying genomic selection (GS) in the line development stage of a hard red winter (HRW) wheat (Triticum aestivum L.) variety development program (VDP), the effectiveness of GS was evaluated by prediction accuracy and by the response to selection across field seasons that demonstrated challenges for crop improvement under significant climate variability. Important breeding targets for wheat improvement in the southern Great Plains of the United States, including grain yield, kernel weight, wheat protein content, and sodium dodecyl sulfate (SDS) sedimentation volume as a rapid test for predicting bread-making quality, were used to estimate the effectiveness of GS across harvest years from 2014 (drought) to 2016 (normal). In general, nonparametric algorithms reproducing kernel Hilbert space (RKHS) and random forest (RF) produced higher accuracies in both same-year cross-validations (CVs) and cross-year predictions for the purpose of line selection. Further, the stability of GS performance was greatest for SDS sedimentation volume but least for wheat protein content. To ensure long-term genetic gain, our study on selection response suggested that across this sample of environmental variability, and though there are cases where phenotypic selection (PS) might be still preferred, training conducted under drought or in suboptimal conditions could provide an encouraging prediction outcome when selection decisions were made in normal conditions. However, it is not advisable to use training information collected from a normal season to predict trait performance under drought conditions. Finally, the superiority of response to selection was most evident if the training population (TP) can be optimized.