Low Mr Glutenin Subunits Research Articles

New B low Mr glutenin subunit alleles at the Glu-A3, Glu-B2 and Glu-B3 loci and their relationship with gluten strength in durum wheat

The B low Mr subunits of glutenin of the F2 generation from three durum wheat crosses were analysed. Three new alleles were found at three different loci: Glu-A3i coding for 5+20 subunits, Glu-B2c coding for subunit 12* and Glu-B3l coding for 1+3+13*+16 subunits. The genetic distances between Glu-A3-Gli-A1, Glu-B2-Gli-B1, Glu-B3-Glu-B2 and Glu-B3-Gli-B1 were calculated. The effects of the allelic variation at the Glu-A3, Glu-B2 and Glu-B3 on protein content and gluten strength, as measured by the SDS-sedimentation test, were determined using F4 lines from the three crosses. All the new alleles affected significantly gluten strength. The presence of Glu-A3i had a negative influence on SDSS values compared with the allele a. For Glu-B2 and Glu-B3 the data obtained enable the effects of the alleles on SDSS volume to be ranked: a=b>c for Glu-B2 and a>b>l for Glu-B3. The results also shown that the allelic variants at Glu-B3 had a much greater effect on gluten strength than the variants at Glu-A3 or Glu-B2 loci. A high percentage of variation in sedimentation volume was explained by the prolamins (52 and 70%).

Thermal stability of wheat gluten protein: its effect on dough properties and noodle texture

There is a need to develop more sensitive and reliable tests to help breeders select wheat lines of appropriate quality. Gluten thermostability, measured by the viscoelasticity of heated gluten, was assessed for its usefulness in evaluating quality of wheats in breeding programs. Two sets of wheat samples were used: Set I consisting of 20 cultivars and/or breeders' lines (BL), with diverse dough strengths and allelic variations of high Mr glutenin subunits coded at the Glu-A1, Glu-B1 and Glu-D1 loci (N=20) and Set II consisting of 16 near isogenic BL of F7 generation that had been in a quality selection program for three years. Thermostability of the isolated wet gluten was determined by measuring its viscoelastic properties, and was related to noodle texture, flour protein content, protein composition, dough physical properties and other quality predicting tests. Viscoelasticity of heat-treated gluten, isolated with 2% NaCl solution, significantly correlated with most of the tests used to measure dough and/or gluten strength and Chinese white salted noodle texture. The rate of thermal denaturation of proteins depends on Mr and packing density. High ratios of monomeric proteins such as gliadins and low Mr glutenin subunits to high Mr glutenin subunits increase the thermostability of the gluten. The measurement of viscoelasticity of heat-denatured gluten can be a useful test to determine gluten quality. Our study showed that gluten viscoelasticity and most of the tests related to dough and/or gluten strength are independent of allelic variations of the high molecular weight glutenin subunits. This test has been developed for predicting white salted noodle quality.

Identification of novel low Mr glutenin subunits in the high quality bread wheat cv Salmone and their effects on gluten quality

Southern-blot hybridization with a probe specific for genes encoding for low M(r) glutenin subunits showed that the high quality bread wheat cv Salmone contains two DNA fragments designated as SF720 and SF750. These fragments were found to occur on the chromosome-1B satellite, and to be associated with the presence of two strongly staining low M(r) glutenin subunits in the two-dimensional A-PAGE x SDS-PAGE pattern of cv Salmone. Comparison of 65 F(6) random lines derived from the cross between cv Salmone and the medium quality line FAP74809 revealed that the presence of fragments SF720 and SF750 had significant positive effects on several quality related parameters such as SDS sedimentation volume, Farinograph stability and Alveograph strength (W), tenacity (P) and elasticity (L). Additive effects of high M(r) glutenin subunits 1 and 7+9 on gluten quality were found as well. Fragments SF720 and SF750 were suggested to occur at a locus other than Glu-B3, as indicated by their relatively high frequency of recombination with the Gli-B1 locus.

Polymorphism of Low Mr Glutenin Subunits in Triticum tauschii

A collection of 173 Triticum tauschii accessions was analysed to evaluate the variability of low molecular weight (Mr) glutenin subunits. These proteins were analysed by one-step one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and were divided into B-, C- and D-subunits in accordance with their electrophoretic mobility. Extensive polymorphism, both in the number and electrophoretic mobility, was detected in lowMr glutenin subunits present in T. tauschii. Thirty different patterns for B-subunits and forty-three for C-subunits were identified, some of which were with identical electrophoretic mobility than those observed in hexaploid wheat. Glutenin subunits with the same electrophoretic mobilities of low Mr D-glutenin subunits as well as subunits encoded at the Glu-D4 and Glu-D5 loci, were also detected in accessions of T. tauschii. These results provide new basic knowledge regarding the genetics variability of the low Mr glutenin subunits, as well as their potential to create novel germplasm for the improvement of wheat quality in breeding programs.

Effect of 1R(1A), 1R(1B) and 1R(1D) Substitution on Technological Value of Bread Wheat

Fifteen wheat (Triticum aestivum L.) substitution lines carrying 1R(1A) or 1R(1B) or 1R(1D) substitutions and derived from nine genetic backgrounds were used to evaluate the effect of the 1R (rye, Secale cereale L.) chromosome on wheat flour quality when substituted with group 1 chromosomes. The substituted lines were identified by the presence of high Mr secalin subunits encoded at Glu-R1 and by the absence of high and low Mrglutenin subunits encoded respectively at the Glu-1 and Glu-3 loci. Direct and indirect technological tests were conducted and intervarietal, year of growth and substitution effects were studied. Alveogram and Mixogram parameters, protein concentration and grain hardness were measured for two years of growth. In addition Zeleny, viscosity of water extractable arabinoxylans (WeAx) and baking tests were carried out on material grown in the second year. Significant differences between years were detected for protein concentration, three parameters of Mixogram (midline peak width MPW, midline right width MRW and weakening slope WS) and two of Alveogram (strength W and swelling G). Intervarietal and substitution effects were shown in the majority of the parameters. The contribution of the three substitutions on breadmaking quality demonstrated that substitution 1R(1A) had a significant positive effect compared to 1R(1B) and 1R(1D) substitutions. The allele encoding high Mr .secalin subunit (6·5) at Glu-R1 had an intermediate value between Glu-A1c (null allele) and subunit 2* encoded at Glu-A1. At Glu-B1, an equivalence was noted between the secalin subunit (6·5) and glutenin subunit 7. However, the secalin subunit (6·5) was always inferior to subunits at Glu-D1. In addition the genetic background was of dramatic importance in explaining the variations, particularly for grain hardness, which declined, when normal lines were of hard type, in the 1R(1A) and the 1R(1D) substitutions. Contrary to what has been found until now, in 1BL/1RS translocation genotypes, substitution decreased WeAx viscosity. Moreover, pentosans and Zeleny explained a great part of the loaf volume variations

Factors Governing Levels and Composition of the Sodium Dodecyl Sulphate-Unextractable Glutenin Polymers During Straight Dough Breadmaking

The effect of several additives (1·215 μmol KIO3, 0·892 μmol cysteine, endo-xylanase and 0·5% (w/w) rye-water-extractable arabinoxylans) on changes in the level and glutenin subunit composition of the sodium dodecyl sulphate (SDS)-unextractable protein during breadmaking was investigated. Protein extractability drastically increased during dough mixing and was enhanced both by cysteine and KIO3. The mixing-induced increase in protein extractability was partly reversed during fermentation. Fermenting doughs containing endo-xylanase had a higher level of SDS-unextractable protein than control doughs, while with KIO3the amount of SDS-unextractable protein remained very low. During baking most protein became SDS-unextractable. Bread baked from doughs with added KIO3contained a significantly higher level of SDS-extractable protein. Changes in subunit composition of the SDS-unextractable glutenin polymers, determined with RP-HPLC, coincided with changes in protein extractability during dough processing. Mixing decreased the ratio of high to lowMrglutenin subunits. Simultaneously, the relative proportions of the different highMrglutenin subunits in the unextractable glutenin polymers changed. During fermentation changes in subunit composition of the SDS-unextractable glutenin were opposite to those during mixing.

Functional Properties of LowMrWheat Proteins.III. Effects on Composition of the Glutenin Macropolymer During Dough Mixing and Resting

Abstract The effect of lowMrwheat protein addition on the amount and composition of the glutenin macropolymer (GMP) of dough was investigated for the three wheat cultivars Obelisk (weak), Camp Remy (medium strong) and Rektor (strong). During mixing, the amounts of high and lowMrglutenin subunit classes, and of the individual subunits decreased. The proportion of highMrglutenin subunits decreased and that of lowMrglutenin subunits increased, indicating an inhomogeneous distribution of the two subunit classes within the polymers present in GMP. During resting, the amounts of the glutenin subunit classes and of individual subunits increased. Meanwhile, the proportion of highMrglutenin subunits in GMP increased. LowMrwheat protein addition retarded re-polymerisation in that the amounts of glutenin subunit classes and of individual highMrglutenin subunits in GMP increased less than without addition. The proportion of highMrglutenin subunits in GMP directly after mixing was also decreased by lowMrwheat protein addition, and the proportion increased faster during dough resting, compared with the GMP in dough without lowMrwheat protein addition. Eventually, after 90 or 135 min resting, no differences existed in the proportions in GMP from doughs with and without lowMrwheat protein addition. LowMrwheat protein addition had no specific effect on individual highMrglutenin subunits, nor on the x-type/y-type subunit ratio in the GMP. In contrast, with increasing lowMrwheat protein addition, a highly significant reduction in the subunit 10 or 12/subunit 9 ratio in GMP was observed. This finding is in line with the decrease in this ratio directly after mixing in GMP of the dough without lowMrwheat protein addition. Since no specific effects were observed, it can be concluded that the lowMrwheat protein acts rather unspecifically on the GMP of dough.

Depolymerisation and Re-polymerisation of Wheat Glutenin During Dough Processing. II. Changes in Composition

tbIn view of the importance of the glutenin macropolymer (GMP) for dough properties and bread-making quality, the changes of composition of glutenin subunits in GMP were investigated for flours and doughs from three cultivars (Rektor, Camp Remy, Obelisk) and from a blend of two of those cultivars (Camp Remy/Obelisk). After mixing, the content of GMP, and the contents of highMrand lowMrglutenin subunits in GMP, decreased. The two subunit classes, and the individual subunits, decreased to different extents, however. This resulted in large changes in their proportions in GMP. After mixing, highMrglutenin subunits accounted for 8–17% of the GMP of dough, whereas in flour they accounted for 29–31%. During dough resting, the amounts of all glutenin subunit classes increased as the amount of GMP increased, but in most cases to lower final levels than those present in the flour. The proportions of highMrglutenin subunits in the GMP of dough increased to levels similar to those present in the GMP of flour (22–31%). The x-type/y-type highMrglutenin subunit molar ratio decreased significantly from 2·42 in the GMP from flour or 2·38 in the GMP from dough directly after mixing, to 1·78–1·83 after 90 min dough resting or longer. This indicates that the GMP became more enriched in y-type subunits during re-polymerisation. In contrast, the highMrglutenin subunit 12/subunit 9 molar ratio in GMP fell significantly from 1·79 for GMP from flour to 1·13 for dough directly after mixing, and increased upon resting to a level similar to that in the GMP from flour. The changes in composition during dough mixing and resting indicate that specific reactions involving glutenin subunits occur during depolymerisation of GMP and during re-polymerisation of the SDS-extractable glutenin polymers.

Preparative Separation of High and Low Molecular Weight Subunits of Glutenin from Wheat

Wheat flour was washed with Tris-HCl buffer containing 4% Triton X114 before extracting the residual gluten with 70% ethanol. The glutenin extraction with 50% ethanol was performed at various ratios of DTT/protein; a minimum ratio of 0·1 g/g was needed to solubilise the maximum amount of glutenin. An experimental design was used to optimise the extraction conditions to obtain the best yield and purity of lowMrand highMrglutenin subunits. The purity of each glutenin subunit fraction was measured by RP-HPLC analysis after reduction and alkylation. Both temperature and protein concentration had an effect on the preparation of these fractions. An increase in the protein concentration enhanced the yield of the highMrglutenin fraction and simultaneously decreased that of the lowMrglutenin. Using the Deringer desirability function, conditions giving the optimum separation were determined. The procedure was scaled up and permitted the preparation of 0·96 g of highMrand 1·64 g of lowMrglutenin subunits from 5 g of gluten. The purities of these fractions, determined by RP-HPLC, were 90% and 95%, respectively, and their amino acid compositions were similar to those of high and lowMrsubunits separated by RP-HPLC.

Effects on Gluten Strength of LowMrGlutenin Subunits Coded by Alleles atGlu-A3andGlu-B3Loci in Durum Wheat

The storage proteins of the F 2 generation from three durum wheat crosses were analysed. Three new alleles were found at three different loci: Gli-B1 (coding for gliadins), and Glu-B3 and Glu-A3 (coding for low M r glutenin subunits), respectively. The effects of the allelic variation at the Glu-B1 , Gli-A1/Glu-A3 and Gli-B1/Glu-B3 loci on gluten strength, as measured by the SDS-sedimentation test, were determined using F 3 seeds from the three crosses. None of the allelic differences at the Glu-B1 or Glu-A3 loci had a significant effect on gluten strength. Allelic variation at the Glu-B3 locus affected gluten quality significantly. A rank of the relative effect of the Glu-B3 alleles on quality is proposed.

Specificity of antisera raised against synthetic peptide fragments of highMrglutenin subunits.

In an attempt to detect highMrglutenin subunits specifically by immunochemical means, antisera were produced against synthetic peptides corresponding to three N-terminal sequences and to two repetitive motifs of highMrglutenin subunits. The three N-terminal peptides, NT1, NT2 and NT3, differed by a single substitution at the sixth position and correspond, respectively, to the N-termini off Dx subunits, Ax and Bx subunits and By and Dy subunits. The anti-peptide sera did not cross react with gliadins or with lowMrglutenin subunits, and differed in their ability to recognise highMrglutenin subunits. The antisera to the repetitive motifs recognised all highMrglutenin subunits, whereas the antisera to the N-terminal peptides detected only some of the subunits. The antiserum directed against the N-terminal peptide from Dx subunits detected these subunits specifically, whereas the antiserum directed against the N-terminal peptide corresponding to y type subunits did not react with the homologous subunits although it did react with Dx or Bx subunits. Antisera were also produced against internal sequences present in the N-terminal domain specific for x and for y-type subunits, but these antisera did not react with the cognate proteins. The failure of some anti-peptide sera to recognise the homologous highMrglutenin subunits may be due to differences in conformation between peptides and the corresponding regions in proteins.

Salt Sensitivity of Acetic Acid-Extractable Proteins of Wheat Flour

The sensitivities of flour proteins to precipitation by NaCl at acid pH were investigated by extraction with 0·05macetic acid solution containing varying concentrations of salt and by precipitation of the proteins extractable in acetic acid solution by addition of salt to varying concentrations. Flours of two Canadian hard red spring wheat cultivars (Glenlea and Katepwa) were used because of their different dough strengths. Electrophoresis results showed that as the NaCl concentration was raised, higherMrproteins of gliadins and glutenins were less extractable and were more easily precipitated. This tendency was more evident for the proteins of cv. Glenlea than those of cv. Katepwa, indicating that the former (stronger) is more sensitive to NaCl than the latter. SDS–PAGE results indicated that differences in the molecular size and subunit composition (i.e.relative proportion of high:lowMrglutenin subunits, and relative proportion of x-:y-type highMrglutenin subunits) of glutenin polymer contribute to differences in NaCl sensitivity. The differences appear to be related to the baking strength of the flour.

Biochemical basis of flour properties in bread wheats. II. Changes in polymeric protein formation and dough/gluten properties associated with the loss of low Mr or high Mr glutenin subunits

Abstract Polymeric protein plays a critical role in governing the functional properties of wheat flour. Wheat genetic lines lacking high M r and, similarly, low M r glutenin subunits from one, two or all three Glu-1 or Glu-3 loci, respectively, were thus used to investigate the effects of these polypeptides on glutenin polymer formation and dough/gluten properties. Polymer formation (quantity, size distribution) was studied by size-exclusion high-performance liquid chromatography (SE-HPLC) using extractable, unextractable and total protein from flour, as well as by diagonal electrophoresis using total protein extracts. The loss of Glu-1 or Glu-3 subunits had significant effects on the quantity of total, extractable and unextractable polymeric protein and on the dough and gluten properties of these lines. Dough and gluten properties were significantly correlated with the proportions of both total and unextractable polymers (a measure of the relative molecular size distribution of polymeric protein), although more strongly with the proportions of unextractable polymers in the case of Glu-1 null lines. The proportion of total polymeric protein decreased more markedly when all the Glu-3 subunits were deleted than when all the Glu-1 subunits were absent, which was in accordance with the relative quantities of these two types of the subunits in the grains. In contrast, loss of all the Glu-1 subunits, on an equal weight basis, reduced the amounts of the larger polymers to a much greater extent than the loss of all the Glu-3 subunits, reflecting more than the molecular size differences in these subunits. SE-HPLC and diagonal electrophoresis of total protein extracts from the triple Glu-1 and Glu-3 null lines also revealed that Glu-1 or Glu-3 subunits form large polymers on their own. When both high and low M r glutenin subunits were present together, however, the amount of large polymer was much greater than the sum of the amounts when only one group was present, suggesting a positive interaction between these two groups of subunits with respect to polymer formation.

Genetic analysis of low Mr glutenin subunits fractionated by two-dimensional electrophoresis (A-PAGE × SDS-PAGE)

Alkylated glutenin subunits of F 7 progenies from the cross between the Italian bread wheat cultivar Costantino and the Canadian cultivar Neepawa were fractionated by one-dimensional A-PAGE and SDS-PAGE and by two-dimensional A-PAGE × SDS-PAGE. Each gliadin allele at the Gli-1 loci of the parental cultivars was shown to be associated with a specific allele at each of the Glu-3 loci, at which low M r glutenin subunits are encoded. The Glu-A3 locus was found to code for two low M r subunits in Neepawa and three in Costantino. In this latter cultivar, eight low M r subunits were assigned to each of the Glu-B3 and Glu-D3 loci, whereas seven subunits were attributed to the Glu-B3 locus and seven to the Glu-D3 locus in Neepawa. A-PAGE × SDS-PAGE can be employed for a detailed description of low M r subunits of glutenin in different cultivars following a genetic approach based on the correspondence between the alleles at the Gli-1 and Glu-3 loci.

Identification of a new low Mr glutenin subunit locus on chromosome 1B of durum wheat

Identification of a new low Mr glutenin subunit locus on chromosome 1B of durum wheat

Immunological Differentiation of Various Gliadins and Low Mr Subunits of Glutenin using Anti-peptide Antisera

Synthetic peptides conjugated to a protein carrier were used to immunise rabbits in an attempt to produce antisera specific for the different classes of gliadins and for the low Mr glutenin subunits of wheat. Eight peptides were selected from regions of low homology situated in the N and C-terminal domains of these proteins. The anti-peptide antisera were assayed gliadin and glutenin fractions of the bread wheat Hardy by immunoblotting after SDS-PAGE separation and by ELISA. Six of the peptides, i.e. N-terminal peptides of α,β-type, γ-type and ω-type gliadins and low Mr glutenin subunits and a C-terminal peptide of α,β-type gliadins, induced antibodies that reacted specifically with the cognate proteins. C-terminal peptides of γ-type gliadins induced antibodies that cross-reacted with ω-type gliadins.

Relationships Between Chromosome 1B-encoded Glutenin Subunit Compositions and Bread-making Quality Characteristics of Some Durum Wheat (Triticum turgidum) Cultivars

Abstract The high and low Mr glutenin subunit compositions (controlled by the Glu-1 loci and the Glu-B3 locus, respectively) and the bread-making quality characteristics of 26 durum wheat (Triticum turgidum) genotypes were determined. The relationships between quality parameters and Glu-B1 and Glu-B3 controlled glutenin subunit composition were also investigated. The Glu-A1-controlled null allele was present in all the genotypes. High Mr subunits 20, 6 + 8 and 7 + 8 occurred in similar proportions in the cultivars analysed. The Glu-B3 low Mr allelic variants, LMW-1 and LMW-2, were both represented, with LMW-1 being present in lower proportion. Flour protein, SDS-sedimentation volume, dough strength (Alveograph W value), dough mixing time and bread loaf volume varied among the genotypes. Most samples had high Alveograph tenacity/extensibility (P/G) ratios, typical of tenacious gluten character. SDS-sedimentation volume, dough strength, dough mixing time and bread loaf volume were all interrelated. An association with flour protein content was observed only for mixing time, while the Alveograph tenacity/extensibility ratio was not correlated with the other parameters. Comparisons within the Glu-B1 and Glu-B3 loci indicated that the high Mr subunit 7 + 8 and the low Mr subunit LMW-2 had significantly greater beneficial effects on gluten strength and bread-making quality than the high Mr subunits 6 + 8 or 20 and the low Mr subunit LMW-1, respectively. High Mr subunit 6 + 8 had greater beneficial effects on quality than subunit 20.

Characterisation of Gluten Subfractions by SE-HPLC and Dynamic Rheological Analysis in Shear

Gluten extracted from defatted flour of the wheat cultivar Aubaine was fractionated by sequential extraction with increasing concentrations of dilute hydrochloric acid, providing 12 fractions in total with different proportions of gliadin and glutenin. The protein compositions and polymer characteristics of these fraction were determined by SDS-PAGE and SE-HPLC on Superose 6, respectively. The SE-HPLC patterns of the fractions showed that they differed in their gliadin-glutenin ratios but also in the size distribution of the glutenin polymers. The rheological behaviour of the fractions was analysed by dynamic assay in shear and was found to be typical of transient network structure. Very large differences in storage and loss moduli were observed between the fractions. A very strong correlation was observed between the plateau modulus and the proportion of the largest glutenin polymers (excluded SE-HPLC peak) in the fractions. Glutenin viscoelasticity is determined primarily by the interactions of large concatenations formed by high and low Mr glutenin subunits.

Allelic Variation at Glutenin Subunit and Gliadin Loci, Glu-1, Glu-3 and Gli-1 of Common Wheats. II. Biochemical Basis of the Allelic Effects on Dough Properties

The biochemical basis of allelic effects of different glutenin subunit loci (Glu-A3, Glu-B3, Glu-D3, Glu-A1, Glu-B1, Glu-D1) and gliadin loci (Gli-A1, Gli-B1, Gli-D1) on dough strength (as measured by Brabender Extensograph or National Mixograph) was studied in a set of 74 recombinant inbred lines from two sites (thus, 148 lines) and in certain biotypes differing only for high Mr glutenin alleles (subunits 5 + 10 and 2 + 12) at the Glu-D1 locus. The relative size distributions of polymeric proteins (native glutenin) and the quantities of glutenin subunits, gliadins and albumins/globulins were determined using SE-HPLC and RP-HPLC/SDS-PAGE. The data revealed that the low Mr glutenin subunit alleles (b and c) at the Glu-B3 locus and alleles (c and e ) at the Glu-A3 locus, giving significantly different Rmax (Extensograph maximum resistance) values, produced B type of low Mr glutenin subunits in different amounts and affected size distribution and/or quantity of the polymeric protein. On the other hand, the alleles at the Glu-B1 and Glu-D1 loci produced high Mr subunits (viz. 17 + 18 and 20 or 5 + 10 and 2 + 12) in similar quantities and only caused differences in the size distributions of the polymeric proteins. Thus, differences other than the quantity of these subunits (e.g. size or polymerising behaviour) are responsible for the different effects of the alleles at the Glu-B1 and Glu-D1 loci on Rmax or MDDT (Mixograph peak dough development time). The relative size distribution of polymeric protein alone could account for all the individual (main effect) and combined (additive and interaction effects) effects of different alleles on dough strength. The quantities of gliadins did not account for the positive effects associated with Glu-3/Gli-1 alleles on dough strength.

Allelic Variation at Glutenin Subunit and Gliadin Loci, Glu-1, Glu-3 and Gli-1, of Common Wheats. I. Its Additive and Interaction Effects on Dough Properties

Fractionation of glutenin subunits by two-step 1-D SDS-PAGE and of gliadins by standard SDS-PAGE revealed that the parents Halberd and (W1 × MMC)/W1/10 had contrasting alleles at each of the six glutenin subunit (Glu-A3, Glu-B3, Glu-D3, Glu-A1, Glu-B1, Glu-D1) and three gliadin (Gli-A1, Gli-B1, Gli-D1) loci located on their group 1 chromosomes. Thus, a set of 74 recombinant inbred lines homozygous for these loci was chosen from a population of 280 randomly selected F3-derived F7 progeny from crosses between these parents to determine individual and combined effects of alleles at these loci on dough properties as measured by the Brabender Extensograph. The allelic effects were tested at two sites giving widely different flour protein levels, maximum dough resistance (Rmax) and dough extensibility (Ext) values; the effects were comparable between the sites as there were no major site × genotype interactions. Flour protein level generally did not vary significantly amongst the progeny groups based on alleles. On the other hand, progeny carrying alleles c and b at the low Mr glutenin subunit loci Glu-A3 and Glu-B3 had significantly greater Rmax values than the alleles e and c, respectively. Similarly, alleles i (bands 17 + 18) and d (bands 5 + 10) at the high Mr glutenin subunit loci Glu-B1 and Glu-D1 , respectively, gave greater Rmax values than the alleles e (band 20) and a (subunits 2 + 12). Alleles at the other loci (Glu-D3 and Glu-A1) did not give significantly different Rmax values. The effects of individual Glu-3 or Glu-1 alleles on Rmax were largely additive, thus together accounting for about 80% of the variability in Rmax among these progeny. Interactions (epistasis) between different Glu-3 and/or Glu-1 loci also affected Rmax significantly, accounting for about another 10% variation. Based on the alleles analysed, different glutenin subunit loci could be ranked as Glu-D1 > Glu-B1 > Glu-B3 > Glu-A3 > Glu-D3 = Glu-A1 with respect to Rmax . In contrast to Rmax, only 25% of the variation in extensibility could be accounted for by the glutenin alleles. Only Glu-D1 and Glu-D3 loci showed significant effects on this parameter.