Molecular Weight Glutenin Subunits Research Articles

Introgression of gluten protein genes associated with the D-genome of bread wheat into durum wheat

In the past thirty years many attempts have been addressed to the possibility to improve the breadmaking characteristics of durum wheat. Since the low breadmaking quality of durum wheat was mainly attributed to the absence of suitable high (HMW-GS) – and low (LMW-GS) molecular weight glutenin subunits, different approaches have been used to introgress D-genome associated LMW-GS HMW-GS, present at the linked Gli-D1/Glu-D3 and Glu-D1 loci. In this paper two sets of durum wheat lines with different introgressions of the D-related glutenin proteins transferred on the short and long arm of chromosome 1A of the recipient variety Svevo, have been characterised. The first set included two lines possessing either the Chinese Spring- (CS) or the Cheyenne- (CNN) type of major alleles at the Gli-D1/Glu-D3 loci, transferred on the short arm of Svevo chromosome 1A. The second group included four lines obtained from crosses between the two lines with the CNN- or CS-type of 1DS alleles with previously obtained durum wheat lines carrying translocations involving the HMW-GS loci Glu-D1a (2 + 12) or Glu-D1d (5 + 10). Quality traits and rheological data were determined for the six translocation lines grown in two different years and compared with the durum variety Svevo. The two translocation lines carrying the two different variants (CS- or CNN-type) at the Gli-D1/Glu-D3 loci behaved differently, the former showing increase of quality characteristics and rheological parameter compared to Svevo, the latter being substantially similar to Svevo. On the contrary, all four double recombinant lines showed maximum values of gluten index and major effects on alveographic parameters due to the presence of the Glu-D1 HMW-GS.

Correlation analysis of HMW sub-units and baking quality-related traits in Indian wheat (Triticum aestivum L.) cultivars

High molecular weight (HMW) glutenin subunits and baking quality-related traits were studied in 50 Indian wheat landraces. Scoring of germplasm based on electrophoresis patterns using the Payne method showed that the quality scores varied from 4 to 8. Based on this scoring, 13 cultivars were ranked as superior. Cluster analysis based on electrophoresis patterns and Jaccard similarity criteria divided the cultivars into five groups, with 13 cultivars in the first cluster. There was no similarity between the grouping pattern based on HMW glutenin sub-units and quality-related traits. In the present study, the quality of the flour of six wheat varieties was weak, so these varieties were only suitable for biscuit making. The flour of 31 wheat varieties showed medium strength. The remaining 13 wheat varieties had strong flour. Considering the great variation observed for quality-related traits and HMW glutenin sub-units, it can be concluded that these cultivars are potential sources of desirable quality traits for use in bread wheat breeding programmes to improve bread-making quality.

Gluten Alleles and Predicted Dough Quality for Wheat Varieties Worldwide: A Great Resource—Free on the AACC International Website

The gluten composition of more than 8,500 wheat varieties is provided in two new databases on the AACC International website (www.aaccnet.org/initiatives/definitions/Pages/Gluten.aspx). The databases augment earlier versions (1–3) by providing a program to screen the large volume of data. For each variety, the program provides the gliadin composition, listed as alleles at the Gli-1 and Gli-2 loci; the high molecular weight subunits of glutenin (HMW-GS), as subunit numbers and alleles at the Glu-1 loci; the low molecular weight subunits of glutenin (LMW-GS), as alleles at the Glu-3 loci; the Payne Glu-1 scores for dough quality; and estimates of dough strength (as Rmax) and extensibility based on both HMW-GS and LMW-GS alleles.

Influence of low-molecular weight glutenin subunits on wheat kernel elasticity and sedimentation volume

The effect of low molecular weight (LMW) glutenin subunits (GS) in presence of high molecular weight (HMW)-GS has over SDS sedimentation volume (SDSS) and kernel elasticity is presented. Twenty-six wheat lines having different origins and classified by SDS-PAGE into 14 different LMW-GS genotypic allelic groups were analyzed. When good HMW-GS background, i.e. Glu-1 1, 2*, 7 + 9 or 17 + 18 and 5 + 10 was associated with a number of allelic variants of Glu-3 loci (LMW-GS), i.e. Glu-A3 c and b; Glu-B3 g, h, d, higher kernel modulus of elasticity and SDSS were generally present. However, when poor HMW-GS background was present, i.e. Glu-1 null, 7 + 8, 2 + 12, a poor to medium modulus of elasticity and SDSS were generally found. Glu-B3 j allelic group, which possesses the wheat-rye translocation showed a tendency to have low elastic modulus, high plastic work (WP) and low SDSS. The effects of good LMW-GS are enhanced by a good HMW-GS background, yielding higher kernel elasticity and SDSS.

Characterization of a novel variant HMW-glutenin gene from Elymus canadensis

High molecular weight (HMW) glutenin subunits (GS) play a key role in the determination of end-use quality of wheat and other cereal crops. In this study, we report the isolation and characterization of both promoter region and ORF of novel HMW-GS allele 1St1.3 from a perennial Triticeae species, Elymus canadensis. The amino acid (AA) sequences of E. canadensis 1St1.3 were deduced as 434 aa. Its protein primary structure comprises a signal peptide with a conserved N-terminal domain, a central repetitive domain and a C-terminal domain. E. canadensis 1St 1.3 possesses several distinct characteristics which are different from those of wheat HMW-GSs. The N-terminal domains of E. canadensis 1St 1.3 resemble that of y-type subunits, while their C-terminal domains are more similar to x-type subunits. The deletion of 85 bp fragment has been observed in promoter region of 1St 1.3, however which has not interrupted the expression of this gene. Our results indicate that 1St 1.3 is novel HMW-GS variants which will be valuable for enhancing our understanding of structural differentiation and the evolutionary relationship among HMW-GSs in Triticeae species.

Structural variation and evolutionary relationship of novel HMW glutenin subunits from Elymus glaucus

High molecular weight (HMW) glutenin subunits (GS) are important seed storage proteins relevant to the end-use quality of wheat and other cereal crops. Here we report the isolation and characterization of two novel HMW-GS alleles (1St 1.4 and 1St1.1) from the perennial Triticeae species Elymus glaucus. The amino acid (aa) sequences of E. glaucus 1St1.4 and 1St1.1 were predicted as 434 aa and 358 aa, respectively. Both subunits comprise a signal peptide with a conserved N-terminal domain, a central repetitive domain and a C-terminal domain. Elymus glaucus 1St 1.4 and 1St1.1 exhibit several distinct characteristics different from other known HMW-GSs. The lengths of repetitive domains in E. glaucus 1St 1.4 and 1St1.1 are substantially smaller than those of other known HMW-GSs, in which 1St1.1 (only 358 aa) is the smallest subunit identified so far. The N-terminal domains of E. glaucus 1St 1.4 and 1St1.1 are homologous to y-type subunits, whereas their C-terminal domains are similar to x-type subunits. Our results indicate that E. glaucus 1St 1.4 and 1St1.1 are novel HMW-GS variants or isoforms, and the characterization of both subunits can enhance our understanding on the structural differentiation and evolutionary relationship of HMW-GSs in Triticeae species.

Proteomic‐based analytical approach for the characterization of glutenin subunits in durum wheat

One of the main objectives of wheat glutenin subunit (GS) analysis is the identification of protein components linked to wheat quality. The proteomic characterization of glutenin has to consider the relatively low levels of arginine and lysine residues and the close sequence similarity among the different groups of these subunits, which hinders or even prevents the identification of the GS. In this study, a proteomic approach has been applied to resolve the heterogeneity of wheat glutenin components. Proteins extracted from Triticum durum flour were first analyzed by two-dimensional gel electrophoresis, which greatly reduced glutenin complexity. The identity of each spot was confirmed by nano liquid chromatography tandem mass spectrometry analysis of tryptic peptides. In parallel, measurements of the high mass range by matrix-assisted laser desorption/ionization time-of-flight analysis allowed detection of the large tryptic peptides. Gathering all data from search engine interrogation, very high sequence coverage was obtained for high molecular weight GS, including Bx7 and By8, in agreement with the known genetic profile of durum wheat. In addition, a truncated form of By8, never detected before, was also found. Low molecular weight GS (LMW-GS) B-type was identified with reasonable sequence coverage, while a clear identification of LWM-GS C- and D-type was hindered by the incompleteness of the wheat DNA databases. This study represents the first comprehensive analysis of the glutenin proteome and provides a reliable method for classifying wheat varieties according to their glutenin profile.

Genetic Control of High Protein Content and Its Association with Bread-Making Quality in Wheat

ABSTRACT A population of recombinant inbred lines (RILs) developed from a cross of Triticum aestivum cvs. WL711 and PH132 using the single-seed descent method was used to investigate the genetics of high protein content and its contribution to bread-making quality. Four-year data on protein content of parents and 124 RILs suggested that the difference in protein content between the two parents was controlled by two major genes with an additive effect. The individual gene gave intermediate protein content. Seven RILs with high protein content and without any yield penalty were selected, multiplied, and investigated for various milling, dough, and bread-making characteristics. PH132 and all seven selected RILs had higher protein content, higher sodium dodecyl sulphate (SDS) sedimentation value, longer dough development time, a lower mixing tolerance index, higher stability, and better loaf volume and loaf quality than the bread wheat cultivars WL711 and PBW343. High molecular weight (HMW) glutenin subunit composition of various high-protein RILs indicated a recombination of parental protein subunits. “2*” coded by Glu-A1 locus, 17 + 18 subunits coded by Glu-B1 locus, and “5 + 10” coded by Glu-D1 locus were predominant. One of the selected RILs, T-74, possessing 2 + 12 at Glu-D1 locus, also had superior bread-making quality, indicating that grain-protein content above a certain minimum value is a relatively more important determinant of bread-making quality than HMW glutenin subunits 5 + 10.

Characterization of two HMW glutenin subunit genes from Taenitherum Nevski

The compositions of high molecular weight (HMW) glutenin subunits from three species of Taenitherum Nevski (TaTa, 2n = 2x = 14), Ta. caput-medusae, Ta. crinitum and Ta. asperum, were investigated by SDS-PAGE analysis. The electrophoresis mobility of the x-type HMW glutenin subunits were slower or equal to that of wheat HMW glutenin subunit Dx2, and the electrophoresis mobility of the y-type subunits were faster than that of wheat HMW glutenin subunit Dy12. Two HMW glutenin genes, designated as Tax and Tay, were isolated from Ta. crinitum, and their complete nucleotide coding sequences were determined. Sequencing and multiple sequences alignment suggested that the HMW glutenin subunits derived from Ta. crinitum had the similar structures to the HMW glutenin subunits from wheat and related species with a signal peptide, and N- and C-conservative domains flanking by a repetitive domain consisted of the repeated short peptide motifs. However, the encoding sequences of Tax and Tay had some novel modification compared with the HMW glutenin genes reported so far: (1) A short peptide with the consensus sequences of KGGSFYP, which was observed in the N-terminal of all known HMW glutenin genes, was absent in Tax; (2) There is a specified short peptide tandem of tripeptide, hexapeptide and nonapeptide and three tandem of tripeptide in the repetitive domain of Tax; (3) The amino acid residues number is 105 (an extra Q presented) but not 104 in the N-terminal of Tay, which was similar to most of y-type HMW glutenin genes from Elytrigia elongata and Crithopsis delileana. Phylogenetic analysis indicated that Tax subunit was mostly related to Ax1, Cx, Ux and Dx5, and Tay was more related to Ay, Cy and Ry.

Molecular structure of a novel y-type HMW glutenin subunit gene present in Triticum tauschii

An unusually small y-type high molecular weight (HMW) glutenin subunit gene from Triticum tauschii was sequenced. This gene, encoded at the Glu-D t 1 locus was designated 12.4 t and is the smallest HMW glutenin subunit gene described so far in Triticum species. Oligonucleotide primers based on published sequences of HMW glutenin genes were designed to amplify the encoding region and the central repetitive domain of the gene, which produced fragments of 1.4 and 0.85 kb, respectively. PCR products were cloned and sequenced. The derived amino acid sequence was compared with the amino acid sequences of the HMW glutenin subunits Dy12 t , from T. tauschii, and subunits Dy10 and Dy12 of T. aestivum. The amino acid sequence deduced from the nucleotide sequence demonstrated that deletions of hexapeptides and nonapeptides were responsible for the reduction in the size of this HMW glutenin subunit. The estimated molecular weight of the Dy12.4 t subunit, calculated on the basis of the deduced amino acid sequence, was 45,228 Daltons. There were also single amino acid differences in the N-, C-terminal and central repetitive domains of this gene in comparison to the three other y-type subunits encoded at the Glu-D1 locus. The Dy12.4 t subunit showed the highest similarity to the Dy12 subunit present in the hexaploid wheat Chinese Spring.

Composition of the glutenin macropolymer: effects of flour quality and nonamylolytic enzyme addition

The effects of the non-amylolytic enzymes pentosanase (PP), glucose oxidase (GLZ) and laccase (LAC), singly and in binary and ternary combinations, and wheat flour—a pure cultivar F0, and low- grade F1 and high-grade F2 commercial blends—on the electro- phoretic pattern of the glutenin macropolymer (GMP) were investigated by sodium dodecyl sulphate polyacry- lamide gel electrophoresis (SDS-PAGE). GMP profiles of high (HMW), medium (MMW) and low (LMW) molecular weight glutenin subunits (GS) were correlated with dough and GMP characteristics and with bread quality and keepability. The total relative percentages of separated HMW, MMW and LMW-GS of GMP in control and enzyme-supple- mented samples were: 33-37, 11-16 and 46-54% (F0), 47-74, 0 and 26-57% (F1) and 30-47, 15-18 and 32- 38% (F2), respectively. HMW-GS/LMW-GS ratios, a quality index of glutenin, were found to range from 0.63 to 0.80 for all flour GMP. Enzyme addition induced moderate effects in pure wheat cultivar F0. Combinations of PP and GLZ (PPGLZ) allowed glutenin repolymeriza- tion after resting, leading to an increase of the bands of 104-107 and 88-90 kDa in GMP by SDS-PAGE. Analogously, PP plus LAC (PPLAC) and LAC alone increased the amount of the subunit of 81-82 kDa. Subunits of LMW increased with PPLAC and LAC, the subunit of 37-38 kDa having a higher percentage in GMP probably due to the presence of a-, b- and g-gliadins besides the LMW-GS. Only the subunit of 81-82 kDa was positively associated with the dynamic rheological moduli G 0 and G* and the subunit of 88-90 kDa correlated with a lower delta angle and, consequently, with a more elastic gel. After fermentation, the total percentage of subunits of HMW, MMW and LMW changed mainly in low-grade flour F1 (36-37, 17-19 and 14-19%) compared with high-grade flour F2 (32-37, 14-17 and 47-51%). The subunit of HMW with MW of 120-125 kDa (F1) and 93- 95 kDa (F2) was positively correlated with the specific volume of breads and negatively with firmness of fresh and stored bread. Subunits of MMW negatively influ- enced the quality of fresh and stored bread of F1. The ratio HMW/LMW was positively correlated with bread firmness during staling in breads prepared with F2.

Effect of ascorbic acid in dough: reaction of oxidized glutathione with reactive thiol groups of wheat glutelin.

The reactions of oxidized glutathione generated from endogenous glutathione by the addition of ascorbic acid (AA) prior to dough mixing on free thiol groups of gluten proteins have been investigated. A small amount of (35)S-labeled glutathione was added as a tracer to identify the reaction products of GSSG and free protein thiols by radioactivity measurement. First, gluten was isolated from the dough, then the gliadins were extracted, and residual glutenin was partially hydrolyzed with thermolysin. After preseparation by gel permeation chromatography, the fractions with the highest radioactivity were separated by high-performance liquid chromatography. Radioactive peptides were identified, isolated, sequenced, and assigned to amino acid sequences of gluten protein components. The isolated peptides contained exclusively the cysteine residues C(b) and C(x) of low molecular weight subunits of glutenin, which are supposed to be highly reactive in forming intermolecular disulfide bonds. From these results it can be assumed that the cysteine residues C(b) and C(x) of the low molecular weight subunits of glutenin are at least partly present in the thiol form in flour. During dough mixing they are converted to protein-protein disulfides or glutathione-protein mixed disulfides by thiol/disulfide interchange reactions. Oxidized glutathione necessary for this reaction is generated from glutathione by the action of AA. These results are in accordance with the major hypothesis about the mechanism of action of AA.

The Relative Amounts of HMW Glutenin Subunits of OS Wheat Cultivars in Relation to Bread-Making Quality

Qualitative and quantitative variation of high molecular weight (HMW) glutenin subunits is very important for wheat bread-making quality. The aim of this investigation was to estimate the relative amounts (%) of HMW glutenin subunits in OS winter wheat cultivars and their contribution to bread-making quality by SDS-PAGE and scanning densitometry. In this paper 10 winter wheat cultivars created at Agricultural Institute Osijek (OS) and cultivar Divana (Jost-Sjeme, KriŽevci), as Croatian standard improver, were investigated. The wheat quality evaluation was done by indirect parameters, rheological properties of dough and baking test. The quantitative analysis of HMW glutenin subunits have demonstrated that subunits encoded at Glu-D1 locus (Dx2, DylO and Dyl2) were the dominant components. Subunit Axl and subunits encoded at Glu-B1 locus (Bx7, By8 and By9) were the minor ones. The proportion of subunit Dx5 depends on presence of subunit Ax1. When subunit Axl was present (1 7+9 5+10) the proportion of subunit Dx5 was approximately 50% reduced. The positive correlation between the relative amounts of the y-type HMW glutenin subunits and extensographic resistance and energy of dough, loaf volumes and appearance of bread (h/d) was found. That indicates that the y-type HMW glutenin subunits are more important for bread-making quality of investigated cultivars than the x-type. This investigation has indicated that the presence of HMW glutenin subunit 1 and both the presence and proportion of subunits 5+10 contributes to very good and good bread-making quality, while good bread-making quality of cultivars with subunits N 7+8(9) 2+12 is due to higher proportion of subunits at Glu-D 1 locus.

Isolation and characterization of five novel high molecular weight subunit of glutenin genes from Triticum timopheevi and Aegilops cylindrica.

Analysis by SDS-PAGE of total protein fractions from single seeds of Aegilops cylindrica (genomes C and D) and Triticum timopheevi (genomes A and G) showed the presence of three bands corresponding to high molecular weight subunits of glutenin (HMW subunits) in the former and two major bands and a minor band corresponding to HMW subunits in the latter. Three Ae. cylindrica and two T. timopheevi HMW subunit gene sequences, each comprising the entire coding region, were amplified by polymerase chain reaction (PCR) and their complete nucleotide sequences determined. A combination of N-terminal amino acid sequencing of the proteins identified by SDS-PAGE and alignments of the derived amino acid sequences of the proteins encoded by the PCR products identified the Ae. cylindrica HMW subunits as 1Cx, 1Cy and 1Dy, and the T. timopheevi HMW subunits as 1Gx, 1Ax and 1Ay. It was not clear whether or not a 1Gy HMW subunit was present in T. timopheevi. The PCR products from Ae. cyclindrica were derived from 1Cy and 1Dy genes and a silent 1Dx gene containing an in-frame internal stop codon, while those from T. timopheevi were derived from 1Ax and 1Ay genes. The 1Cx, 1Gx and 1Gy sequences were not amplified successfully. The proteins encoded by the five novel genes had similar structures to previously characterized HMW subunits of bread wheat ( Triticum aestivum). Differences and similarities in sequence and structure, and in the distribution of cysteine residues (relevant to the ability of HMW subunits to form high M(r) polymers) distinguished the HMW subunits of x- and y-type and of each genome rather than those of the different species. There was no evidence of a change in HMW subunit expression or structure resulting from selective breeding of bread wheat. The novel 1Ax, 1Ay, 1Cy and 1Dy HMW subunits were expressed in Escherichia coli, and the expressed proteins were shown to have very similar mobilities to the endogenous HMW subunits on SDS-PAGE. The truncated 1Dx gene from Ae. cylindrica failed to express in E. coli, and no HMW subunit-related protein of the size predicted for the truncated 1Dx subunit could be identified by immunodetection in seed extracts.

Glutenin composition, quality characteristics, and agronomic attributes of durum wheat cultivars released in Ethiopia

Eleven cultivars of durum wheat (Triticum durum L. var. durum Desf.) were evaluated across five environments in Ethiopia for grain yield, 1000 kernel weight, protein concentration, gluten strength, mixing time, mixing height, colour and yellow berry to identify desirable traits for breeding purposes. Gluten strength was measured by the sodium dodecyl sulfate (SDS) sedimentation test. An electrophoretic study of gliadin and glutenin proteins was undertaken to investigate possible associations between these proteins and gluten strength. Significant genotypic differences were observed for grain yield, 1000 kernel weight, protein content, SDS-sedimentation volume, yellowness and yellow berry. Six high molecular weight (HMW) glutenin subunits patterns were identified with the combination of null and 20 being the most common. For Glu-B1, the alleles producing protein subunits of 20 and 7+8 were the most common. Alleles producing protein subunits of 6+8 were less frequently observed. Three cultivars had pattern LMW-1 while the remaining eight cultivars had pattern LMW-2. The strongest gluten strength corresponded to the mixed subunits 7+8/6+8 and 7+8/20, followed by subunits 6+8 and 7+8. Subunit 20 was associated with the lowest gluten strength. Pattern LMW-2 was strongly associated with higher gluten strength compared to LMW-1. The effects of low molecular weight (LMW) and HMW glutenin subunits were additive. In order to develop high quality durum wheats, it would be useful to discard lines with LMW-1 and HMW glutenin subunit 20 and to combine electrophoretic analysis with the SDS-sedimentation test.

The HMW Glutenin Subunit Composition of OS Wheat Cultivars and their Relationship with Bread-Making Quality

High molecular weight (HMty) glutenin subunits are known as one of the most important components determining functional properties of wheat flour. The aim of this paper was to investigate HMW glutenin subunit composition of OS wheat cultivars and their contribution to bread-making quality. HMW glutenin subunits of 15 OS wheat cultivars were determinated by sodiurn dodecyl sulfate (SDS) Polyacrylamide gel electrophoresis and Ultroscan laser densitometer. The quality parameters of wheat grain: protein contents, sedimentation value, wet gluten, gluten index, rheological properties of flour and loaf volume, were measured. In the investigated OS wheat cultivars the most frequently subunits in the locus Glu-Al were N, in the locus Glu-B1 7+9 and in the locus Glu-D1 2+12. The quality scores of each subunit were summed to create a Glu-1 quality score that ranged from 5 to 9 for OS wheat cultivars. The positive correlation between Glu-1 score and gluten index as well as extensographic properties of dough of investigated wheat cultivars, were noticed.

Importance of amounts and proportions of high molecular weight subunits of glutenin for wheat quality

High molecular weight (HMW) subunits of wheat glutenin are generally considered to play a key role in gluten formation and structure, and to be closely related to wheat quality. Though quantities of HMW subunits in flour have been proposed to be as important for wheat quality as their structures, only few quantitative data are available in the literature. Therefore, two assortments of wheat consisting of 13 international and 16 German cultivars were analyzed for their contents and proportions of single HMW subunits using an extraction and HPLC procedure on a micro-scale. The results were compared with quantitative data from the literature that were obtained by sodium dodecylsulfate polyacrylamide gel electrophoresis combined with densitometry or by reversed-phase HPLC combined with UV detection. The quantitative analyses demonstrated that the contents of HMW subunits varied within a broad range dependent on genotype and growing conditions. The proportions of subunits within a given subunit combination, however, varied only within a small range. Generally, subunits 2, 5, 7, 10 and 12 were major components and subunits 1, 2*, 6, 8 and 9 were minor components. The levels of HMW subunits were highly correlated to dough development time, maximum resistance of dough and gluten, and bread volume. Among HMW subunits the x-type components (subunits 1–7) were much more important than the y-type components (subunits 8–12). In particular, the presence of subunit 5 (which has an additional cysteine residue) and of subunit 7 (which occurs in the greatest amounts) contributed to high wheat quality.

Identification of alleles for complex gene loci Glu-A1, Glu-B1, and Glu-D1, which code for high molecular weight subunits of glutenin in Japanese hexaploid wheat varieties.

Seed storage proteins of Japanese wheat (Triticum aestivum) varieties were fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to identify the alleles for complex gene loci, Glu-A1, Glu-B1, and Glu-D1, which code for high molecular weight (HMW) subunits of glutenin in Japanese hexaploid wheat varieties. These were identified by comparison of subunit mobility with those previously found in hexaploid wheat. Twenty-four different, major glutenin HMW subunits were identified, and each variety contained three to five subunits. Seventeen different glutenin subunit patterns were observed for 14 alleles in Japanese varieties. A catalog of alleles for the complex gene loci, Glu-A1, Glu-B1, and Glu-D1, that code for HMW subunits of glutenin in hexaploid wheat was compiled. Japanese varieties showed some special allelic variation in glutenin HMW subunits that was different from those in hexaploid wheats of other countries.

Effects of Wheat Bug (Eurygaster maura) Protease on Glutenin Proteins

ABSTRACTProteolytic degradation of 50% 1‐propanol insoluble (50PI) glutenin of six common wheat cultivars by wheat bug (Eurygaster maura) protease was investigated using reversed‐phase HPLC. Wheat at the milk‐ripe stage was manually infested with adult bugs. After harvest, bug‐damaged kernels were blended (2:1, kernel basis) with undamaged grain of the same cultivar. Samples of ground wheat were incubated in distilled water for different times (0, 30, 60, and 120 min). The incubated whole meal samples were subsequently freeze‐dried and stored until analysis. The degree of proteolytic degradation of 50PI glutenin was determined based on the quantity of total glutenin subunits (GS), high molecular weight GS (HMW‐GS), and low molecular weight GS (LMW‐GS). For ground wheat samples incubated for ≥30 min, 50PI glutenin was substantially degraded as evidenced by a >80% decrease on average in total GS, HMW‐GS, and LMW‐GS. Some cultivars showed different patterns of glutenin proteolysis as revealed by differences in the ratios of HMW‐GS to LMW‐GS between sound and bug‐damaged samples; a significant decrease in this ratio was found for four cultivars. This evidence, combined with other observations, indicated that there were intercultivar differences in polymeric glutenin resistance to the protease of the wheat bug Eurygaster maura. While the nature of this resistance is unknown, it should be possible to select and develop wheat cultivars with improved tolerance for wheat bug damage. Propanol insoluble glutenin, which corresponds to relatively large glutenin polymers, appears to be an excellent quantitative marker for this purpose.

Effects of wheat bug (Eurygaster maura) proteolytic enzymes on electrophoretic properties of gluten proteins

Hydrolysis of gluten proteins of six bread wheat (Triticum aestivum L.) cultivars damaged by Eurygaster maura was investigated by acid polyacrylamide gel electrophoresis (A‐PAGE) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Electrophoresis results showed that bug proteolytic enzymes clearly affected gliadin and glutenin proteins of damaged wheats. Some new bands of low and high mobility appeared in the A‐PAGE electrophoregrams. These new bands and the bands in the original gliadin and glutenin patterns disappeared with increasing incubation times. Especially high molecular weight (HMW) glutenin subunits were most strongly affected by the bug protease, and disappeared at 120 min of incubation (except ‘Ankara'). However, some of the low molecular weight (LMW) glutenin subunits were not affected as much as HMW glutenin subunits and were still visible even after the longest incubation time investigated. Electrophoretic patterns of some cultivars with the same level of proteolytic activity were affected differently, indicating an intercultivar variation in susceptibility to hydrolysis by bug proteolytic enzymes.