Glu-1 Loci Research Articles

Allelic variation of LMW-GS composition in Chinese wheat landraces of the Yangtze-River region detected by MALDI-TOF-MS.

Low molecular weight glutenin subunits are important components of wheat storage proteins, which play an important role in determining end-use quality of common wheat. A newly established matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) procedure was used to analyze 478 landraces of bread wheat collected from the Yangtze-River region in China. Results indicated that 17 alleles at three loci: Glu-A3, Glu-B3 and Glu-D3 were identified, resulting in 87 different allele combinations. Of the 17 alleles detected at all the Glu-3 loci, five belonged to Glu-A3, seven to Glu-B3 and five to Glu-D3 locus. MALDI-TOF-MS indicated Glu-A3a/c was present in 72.8%, Glu-A3b in 8.4%, Glu-A3d in 8.4%, Glu-A3f in 5.2% and Glu-A3e in 3.6% lines. Seven types of alleles were identified at the Glu-B3 locus: Glu-B3d/i (25.5%), Glu-B3b (21.3%), Glu-B3c (16.9%), Glu-B3h (13.8%), Glu-B3f (8.4%), Glu-B3a (8.2%), and Glu-B3g (5.2%). Five types of Glu-D3 alleles were detected: Glu-D3a (58.4%), Glu-D3c (22.6%), Glu-D3d (15.5%), Glu-D3b (3.3%) and Glu-D3f (0.2%). Four new alleles that showed abnormal MALDI-TOF spectrum patterns were identified at the Glu-A3 and Glu-B3 loci. A detailed study is needed to further characterize these alleles and their potential usage for wheat improvement.

The inheritance of endosperm storage proteins by the line of the Saratovskaya 29 cultivar of common wheat from its parental forms

We ran a comparative analysis of storage proteins (gliadins, high- (HMW) and low-molecular-weight (LMW) glutenins, puroindolines, and exogenous α-amylase pest inhibitors) in the Saratovskaya 29 cultivar line from the collection of a genetic engineering laboratory, its parental forms (Albidum 24 and Lyutescens 55/11), and distant ancestors (Poltavka, Selivanovskiy Rusak, Sarroza, and tetraploid Beloturka). It was confirmed that the allelic states of storage proteins in the Gli-1, Gli-2 and Glu-1 loci originate from ancestral forms from the collection of the Vavilov Institute of Plant Industry. Moreover, new alleles were found in Lyutescense 55/11 (Glu-Ala) and Selivanovskiy Rusak (Glu-B1b) cultivars from the collection of the Institute of Cytology and Genetics. A new allelic state, Ha, was observed in the loci of the Poltavka cultivar as a soft-grain cultivar, and the ha allele was found in the hard-grain Albidum 24 and Sarroza cultivars. It was found that the expression rate of exogenous α-amylase inhibitors of pests in the Saratovskaya 29 cultivar line is lower than that of ancestral cultivars (Albidum 24, Sarroza, Poltavka, and Beloturka). Such inhibitors are absent in the paternal form Lyutescense 55/11. A high expression rate of protein pest inhibitors for exogenous α-amylases and puroindolines was observed in the Poltavka cultivar. The allelic composition of Glu-1 loci was newly studied in the Sarroza cultivar, which has some promising features. The Saratovskaya 29 cultivar line, on the basis of which a wide range of diverse lines were created in the Institute of Cytology and Genetics, is isogenic for all of the studied traits.

Characterization of high molecular weight glutenin subunits of Wheat genotypes

End use quality of wheat is an important goal for developing elite genotypes. Glutenins are considered key factors in improving processing quality, particularly high molecular weight glutenin subunits (HMW-GS). The HMW-GS are known to be encoded by three Glu-1 loci located on the long arms of chromosomes 1A, 1B and 1D. The endosperm storage proteins of 90 advanced breeding lines developed for peninsular zone of India were analysed by SDS-PAGE to determine their HMW-GS compositions. A total of ten alleles were identified: three at Glu-A1 , five at Glu-B1 , and two at Glu-D1 . In Glu-A1 locus, null, 1 and 2* alleles were found with the frequency of 48%, 30% and 22%. Whereas, in Glu-B1 , 5 alleles with frequency of 17+18 (33%), 7+9 (27%), 7 (25%), 6+8 (9%), and 20 (6%) were detected. In Glu-D1 locus, 2+12 and 5+10 were marked with the frequency of 60% and 40%, respectively. Quality score of genotypes were ranged from 4 to 10, with an average of 6.95 indicating vast genetic diversity among the genotypes. The presence of subunits combinations in different varieties with low, medium and high gluten strength revealed that breeding wheat for bread, chapatti and biscuits is possible as per end use requirement.

Rapid Development of Glu-1 Locus Near-isogenic Introgression Lines Using HMW-GS Deletion Mutant

Wheat (Triticum aestivum L., AABBDD) high molecular weight glutenin subunits (HMW-GS) were encoded by the genes located in Glu-A1, Glu-B1, and Glu-D1 loci. Evaluation and optimization of the combination of HMW-GS are very important to understand Glu-1 functions. In this study, we constructed a HMW-GS deletion mutant, DLGlu1 with Xiaoyan 81 background, and crossed it with Glenlea, a Canada elite wheat variety with superior end-use quality. Combining the technologies of wheat embryo culture and molecular marker-assisted selection (MAS), we obtained seven introgression lines containing Glenlea Glu-A1a, Glu-B1al, and Glu-D1d loci, which can be developed as a complete set of near-isogenic introgression lines possessing Glenlea different HMW-GS genes. Our study indicated that the Glu-1 deletion mutant DLGlu1 is of great value in the fast development of Glu-1 near-isogenic introgression lines and the study and utility of wheat Glu-1.

Identification of Low Molecular Weight Glutenin Alleles by Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF-MS) in Common Wheat (Triticum aestivum L.).

Low molecular weight glutenin subunits (LMW-GS) play an important role in determining dough properties and breadmaking quality. However, resolution of the currently used methodologies for analyzing LMW-GS is rather low which prevents an efficient use of genetic variations associated with these alleles in wheat breeding. The aim of the current study is to evaluate and develop a rapid, simple, and accurate method to differentiate LMW-GS alleles using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. A set of standard single LMW-GS allele lines as well as a suite of well documented wheat cultivars were collected from France, CIMMYT, and Canada. Method development and optimization were focused on protein extraction procedures and MALDI-TOF instrument settings to generate reproducible diagnostic spectrum peak profiles for each of the known wheat LMW-GS allele. Results revealed a total of 48 unique allele combinations among the studied genotypes. Characteristic MALDI-TOF peak patterns were obtained for 17 common LMW-GS alleles, including 5 (b, a or c, d, e, f), 7 (a, b, c, d or i, f, g, h) and 5 (a, b, c, d, f) patterns or alleles for the Glu-A3, Glu-B3, and Glu-D3 loci, respectively. In addition, some reproducible MALDI-TOF peak patterns were also obtained that did not match with any known alleles. The results demonstrated a high resolution and throughput nature of MALDI-TOF technology in analyzing LMW-GS alleles, which is suitable for application in wheat breeding programs in processing a large number of wheat lines with high accuracy in limited time. It also suggested that the variation of LMW-GS alleles is more abundant than what has been defined by the current nomenclature system that is mainly based on SDS-PAGE system. The MALDI-TOF technology is useful to differentiate these variations. An international joint effort may be needed to assign allele symbols to these newly identified alleles and determine their effects on end-product quality attributes.

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

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

Analysis of Allelic Variation in Hmw-Glu-1 Gene Blocks in Iranian Wheat Cultivars using Alp Molecular Marker

AbstractIn order to study the allelic variation of Glu-1 gene (High molecular weight glutenin), 100 Iranian wheat cultivars including imported and domestic genotypes were analyzed using ALP-PCR technique. Four specific primer pairs were used based on the genetic loci of Glu-A1, Glu-B1, and Glu-D1 to perform the chain polymerase reactions. PCR reaction products were resolved on 2% agarose gel. Since allele “a” had the largest relative frequency (0.707), two alleles (a 344bp; b 362bp) were identified by P1-P2 primer for Glu-A1 locus. Three alleles (a 800bp; b 500bp; c 300bp) were detected for Glu-B1 locus by P5-P6 primer, and allele “b” was assumed as the highest relative frequency (0.618). Two primer pairs were applied for Glu-D1 locus. Ultimately, four alleles were identified, where allele “c” had the highest relative frequency (0.525). The observed genetic variation value for Glu-D1 locus (H=0.648) exhibits the maximal polymorphism. Using cluster analysis, the relationship between the observed polymorphism and geographical variation was investigated. The results indicated that there exists a remarkable variation in Glu- A1 locus between the Iranian wheat cultivars.

Diversity of phenotypic (plant and grain morphological) and genotypic (glutenin alleles in Glu-1 and Glu-3 loci) traits of wheat landraces (Triticum aestivum) from Andalusia (Southern Spain)

Forty-six landraces from Andalusia, region in southern Spain, were characterized for plant, spike and grain morphology and for HMWGs and LMWGs composition. Up to five botanical varieties were identified among these materials based in four morphological traits. According to grain colour, nine accessions showed heterogeneity. The remaining morphological traits showed wide variation. The analysis for HMWGs and LMWGs showed that the variation of these lines indicates that up to 77 genotypes could be found in these 46 accessions. The analysis for the HMWGS, detected a novel allele for Glu-A1 (subunit 1‴) found in four lines (BGE012113 var. aureum; BGE013163 var. hostianum; BGE012196 and BGE026948 var. lutescens), and for Glu-D1 (subunits 3*+T2) present in only one line derived from the BGE036374, var. aestivum. For the LMWGs a new allele for the Glu-B3 locus was detected. The allelic variation at the Glu-1 and Glu-3 showed a clear risk of genetic erosion due to the low frequency of some alleles. The characterization of these landraces could permit the evaluation of the relationship between the uses of these flours and the composition of their seed storage proteins. The recovery of old varieties or landraces is significant for farmers who can plant the materials and benefit from their potential value in the marketplace.

High-molecular-weight glutenin subunit-deficient mutants induced by ion beam and the effects of Glu-1 loci deletion on wheat quality properties.

High-molecular-weight glutenin subunits (HMW-GSs) play a critical role in determining the viscoelastic properties of wheat. Mutations induced by ion beam radiation have been applied to improve the yield and quality of crop. In this study, HMW-GS-deficient mutant lines were selected and the effects of Glu-1 loci deletion on wheat quality properties were illustrated according to the analysis of dry seeds of common wheat (Triticum aestivum L.) Xiaoyan 81 treated with a nitrogen ion beam. Three HMW-GS-deficient mutant lines were obtained and then detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Large-chromosome-fragment deletion resulted in specific deficiencies, and the deleted region sizes were determined using molecular markers. Agronomic characters, quantity and proportion of glutenins and dough microstructure of the deletion lines all proved to be quite different from those of wild-type Xiaoyan 81. Analysis of quality properties suggested that GluA1(-) had superior property parameters, while GluB1(-) and GluD1(-) both showed a significant decrease in quality properties compared with Xiaoyan 81. The effects of the three Glu-1 loci on flour and dough quality-related parameters should be Glu-D1 > Glu-B1 > Glu-A1. Ion beam radiation can be used as a mutagen to create new crop mutants.

Influence of allelic prolamin variation and localities on durum wheat quality

Thirty-seven varieties of a Mediterranean durum wheat collection grown in Tunisia and Spain were analysed for their allelic composition in prolamins, as well as their protein concentration, sodium dodecyl sulphate sedimentation (SDSS) test and mixograph parameters. Genotype was a greater source of variation in all measurements than locality. Uncommon high and low molecular glutenin subunits (HMW-GS and LMW-GS) were found (V and 2•• subunits at Glu-A1, 13 + 16 at Glu-B1, 5* subunit and ax allele at Glu-A3). The rare combinations 2 + 4+14 + 18 and 8 + 9+13 + 16+18 subunits at the Glu-B3 locus were found. Glu-A3ax had a positive influence on SDSS and mixograph parameters. Of all the prolamins, those that have the B-LMW-GS composition aaa (for Glu-A3, Glu-B3 and Glu-B2 loci, respectively), when associated with the Glu-A1c and Glu-B1d gave the best semolina quality. By contrast, semolina quality is poor when this same composition is associated with the Glu-A1c and Glu-B1e and even poorer when associated with the Glu-A1c and Glu-B1f. In addition, the cultivars with B-LMW-GS allelic composition aab (for Glu-A3, Glu-B3 and Glu-B2 loci, respectively), when associated with the Glu-A1c and Glu-B1d, gave high quality, whereas when associated with the Glu-A1c and Glu-B1e or with Glu-A1o and Glu-B1f, the quality was very poor.

Composition, variation, expression and evolution of low-molecular-weight glutenin subunit genes in Triticum urartu.

BackgroundWheat (AABBDD, 2n = 6x = 42) is a major dietary component for many populations across the world. Bread-making quality of wheat is mainly determined by glutenin subunits, but it remains challenging to elucidate the composition and variation of low-molecular-weight glutenin subunits (LMW-GS) genes, the major components for glutenin subunits in hexaploid wheat. This problem, however, can be greatly simplified by characterizing the LMW-GS genes in Triticum urartu, the A-genome donor of hexaploid wheat. In the present study, we exploited the high-throughput molecular marker system, gene cloning, proteomic methods and molecular evolutionary genetic analysis to reveal the composition, variation, expression and evolution of LMW-GS genes in a T. urartu population from the Fertile Crescent region.ResultsEight LMW-GS genes, including four m-type, one s-type and three i-type, were characterized in the T. urartu population. Six or seven genes, the highest number at the Glu-A3 locus, were detected in each accession. Three i-type genes, each containing more than six allelic variants, were tightly linked because of their co-segregation in every accession. Only 2-3 allelic variants were detected for each m- and s-type gene. The m-type gene, TuA3-385, for which homologs were previously characterized only at Glu-D3 locus in common wheat and Aegilops tauschii, was detected at Glu-A3 locus in T. urartu. TuA3-460 was the first s-type gene identified at Glu-A3 locus. Proteomic analysis showed 1-4 genes, mainly i-type, expressed in individual accessions. About 62% accessions had three active i-type genes, rather than one or two in common wheat. Southeastern Turkey might be the center of origin and diversity for T. urartu due to its abundance of LMW-GS genes/genotypes. Phylogenetic reconstruction demonstrated that the characterized T. urartu might be the direct donor of the Glu-A3 locus in common wheat varieties.ConclusionsCompared with the Glu-A3 locus in common wheat, a large number of highly diverse LMW-GS genes and active genes were characterized in T. urartu, demonstrating that this progenitor might provide valuable genetic resources for LMW-GS genes to improve the quality of common wheat. The phylogenetic analysis provided molecular evidence and confirmed that T. urartu was the A-genome donor of hexaploid wheat.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0322-3) contains supplementary material, which is available to authorized users.

Effect of allelic variation at the Glu-3/Gli-1 loci on breadmaking quality parameters in hexaploid wheat (Triticum aestivum L.)

Low molecular weight glutenin subunits (LMW-GS) encoded by the Glu-3 loci are known to contribute to wheat breadmaking quality. However, the specific effect of individual Glu-3 alleles is not well understood due to their complex protein banding patterns in SDS-PAGE and tight linkage with gliadins at the Gli-1 locus. Using DNA markers and a backcross program, we developed a set of nine near isogenic lines (NILs) including different Glu-A3/Gli-A1 or Glu-B3/Gli-B1 alleles in the genetic background of the Argentine variety ProINTA Imperial. The nine NILs and the control were evaluated in three different field trials in Argentina. Significant genotype-by-environment interactions were detected for most quality parameters indicating that the effects of the Glu-3/Gli-1 alleles are modulated by environmental differences. None of the NILs showed differences in total flour protein content, but relative changes in the abundance of particular classes of proteins cannot be ruled out. On average, the Glu-A3f, Glu-B3b, Glu-B3g and Glu-B3iMan alleles were associated with the highest values in gluten strength-related parameters, while Glu-A3e, Glu-B3a and Glu-B3iChu were consistently associated with weak gluten and low quality values. The value of different Glu-3/Gli-1 allele combinations to improve breadmaking quality is discussed.

Genetic Variation in Glutenin Protein Composition of Aestivum and Durum Wheat Cultivars and Its Relationship with Dough Quality

Genetic variability of high molecular weight glutenin subunits and low molecular weight glutenin subunits composition at the Glu-1 loci in Triticum aestivum L., and T. durum L., wheat was studied using sodium dodecyl sulfate polyacrylamide gel electrophoresis and polymerase chain reaction based markers. The end use quality of wheat is mainly influenced by the composition of glutenin protein. Aestivum cultivar GW-273 showed highest gluten index (94.4%) and sedimentation value (61 mL). GW-273 and GW-322 showed highest Glu-1 score of 10 out of 10, indicating superior dough quality for bread making. Results from glutenin protein separation using electrophoresis revealed that selected Indian wheat cultivars were abundant in high molecular weight glutenin subunits AxNull allele, which is responsible for poor quality. Gene specific polymerase chain reaction using high molecular weight glutenin subunits and low molecular weight glutenin subunits primers showed Dx5 and Dy10 in only two cultivars GW-273 and GW-322, which is responsible for good dough quality. Sequencing of high molecular weight glutenin subunits Dx5 gene fragment showed four cysteine at the N-terminal end. Cysteine residues are helpful in intermolecular disulfide bond formation among different glutenin and gliadins proteins leading to good elasticity of dough.

Allelic variations of functional markers for high molecular weight glutenin genes in Indian wheat (Triticum aestivum L.) cultivars and their correlation with bread loaf volume

Glutenins, the polymeric proteins are composed of high molecular weight (HMW) and low molecular weight (LMW) glutenin subunits. High molecular weight glutenin subunit (HMW-GS) plays a key role in determining bread making quality. The HMW-GS encoded by Glu-1 loci (GluA1, GluB1 and GluD1) are highly polymorphic. Thus it is very important to identify the alleles at Glu-1 loci for all three genomes for wheat quality improvement. In the present study 53 Indian wheat genotypes were evaluated for HMW-GS composition using PCR-based DNA markers. In total, two alleles (Ax2*, Ax1 or Axnull) at Glu-A1, four allele/allelic pairs (Bx7, Bx7 + By8, Bx7 + By9, Bx17 + By18) at Glu-B1 and two allelic pairs (Dx2 + Dy12 and Dx5 + Dy10) at Glu-D1 were identified using diagnostic DNA markers. Allele or allelic pair Ax2* (62.3 %) at Glu-A1, Bx7 + By8 (64 %) at Glu-B1 and Dx2 + Dy12 (58.5 %) at Glu-D1 were present most frequently in wheat genotypes taken for study. Moreover, the allelic combination Ax2*, Bx17 + By18 and Dx5 + Dy10 exhibited highest bread loaf volume in comparison to other allelic combinations studied. The set of markers used here thus represents a useful alternative for screening of HMW-glutenin allele (s) for improvement of bread making quality in Indian wheat genotypes.

Analysis of Allelic Variation in HMW-Glu-1 Gene Blocks in Iranian Wheat Cultivars using ALP Molecular Marker

In order to study the allelic variation of Glu-1 gene (High molecular weight glutenin), 100 Iranian wheat cultivars including imported and domestic genotypes were analyzed using ALP-PCR technique. Four specific primer pairs were used based on the genetic loci of Glu-A1, Glu-B1, and Glu-D1 to perform the chain polymerase reactions. PCR reaction products were resolved on %2 agarose gel. Since allele had the largest relative frequency (0.707), two alleles (a 344bp; 362bp) were identified by P1-P2 primer for Glu-A1 locus. Three alleles (a 800bp; 500bp; 300bp) were detected for Glu-B1 locus by P5-P6 primer, and allele b was assumed as the highest relative frequency (0.618). Two primer pairs were applied for Glu-D1 locus. Ultimately, four alleles were identified, where allele c had the highest relative frequency (0.525). The observed genetic variation value for Glu-D1 locus (H=0.648) exhibits the maximal polymorphism. Using cluster analysis, the relationship between the observed polymorphism and geographical variation was investigated. The results indicated that there exists a remarkable variation in Glu-1 locus between the Iranian wheat cultivars.

Identification and evaluation of disease resistance and HMW-GS composition of Aegilops geniculata Roth

Aegilops geniculata Roth is an important germplasm resource for the transfer of beneficial genes from alien species of wheat into common wheat (Triticum aestivum L.). In this study, we identified and evaluated agronomic characters, powdery mildew resistance, stripe rust resistance, and high molecular weight glutenin subunit (HMW-GS) compositions of 44 Ae.geniculata accessions. The average growth period (254 days) was longer than that of common wheat (240 days). Coefficients of variation (CVs) of all examined agronomic characters except growth period were >10 %. The largest CV, 23.80 %, was that of 1,000-grain weight. An assay for disease resistance revealed that 37 Ae.geniculata accessions (85.09 %) were resistant to powdery mildew, of which 33 were immune, 1 was highly resistant, and 3 were moderately resistant. This assay also indicated that 33 of the accessions (75 %) were resistant to stripe rust, with 25 showing immunity, 4 highly resistant, and 4 moderately resistant. Additionally, 19 accessions (43.18 %) were immune to both powdery mildew and stripe rust. HMW-GSs in the 44 accessions were analyzed by SDS polyacrylamide-gel electrophoresis, which indicated rich germplasm diversity. A total of 21 different HMW-GS alleles were identified at Glu-1 loci. The most frequent subunits were 1Dx2, 1Dx1.1, 1Dx2.2, 1Dx1.5, 1Bx20, 1Bx22, 1Dy10, and 1Dy12, found in 36.36, 54.55, 40.91, 34.09, 38.64, 25.00, 47.73, and 20.45 % of accessions, respectively. The data uncovered for the 44 accessions should facilitate their use as beneficial germplasm donors in wheat breeding.

Genetic divergence for high-molecular weight glutenin subunits (HMW-GS) in indigenous landraces and commercial cultivars of bread wheat of Pakistan.

Wheat flour quality is an important consideration in the breeding and development of new cultivars. A strong association between high-molecular weight glutenin subunits (HMW-GS) and bread making quality has resulted in the widespread utilization of HMW-GS in wheat breeding. In this study, we analyzed 242 lines of wheat, including landraces from the provinces of Punjab and Baluchistan, as well as the commercial varieties of Pakistan, to determine allelic variation in the Glu-A1, Glu-B1, and Glu-D1 loci encoding HMW-GS. Higher genetic diversity was observed for HMW-GS in landraces from Baluchistan, followed by landraces collected from Punjab and then commercial varieties. Rare and uncommon subunits were observed in Glu-B1, whereas Glu-A1 was less polymorphic. However, Glu-B1 was the highest contributor to overall diversity (78%), with a total of 31 rare alleles, followed by Glu-D1 (20%) with the high quality 5+10 allele and other variants. Commercial cultivars possessed favorable alleles, potentially from indirect selection for wheat flour quality by the breeders; however, this indirect selection has decreased the pedigree base of commercial cultivars. The allelic combinations, including 2*, 5+10, and 17+18, showing high quality scores were frequent among landraces, indicating their usefulness in future crop improvement and breeding programs.

Allelic variation inGlu-1andGlu-3loci of bread wheat (Triticum aestivumssp.aestivumL. em. Thell.) germplasm cultivated in Algeria

Wheat endosperm storage proteins are the major components of gluten. They play an important role in dough properties and in bread making quality in various wheat varieties. In the present study, the different alleles encoded at the 6 glutenin loci were identified from a set of 71 hexaploid wheat germplasm cultivated in Algeria using SDS-PAGE. At Glu-A1, Glu-B1 and Glu-D1, encoding high molecular weight glutenin subunits (HMW-GS), 3, 6 and 5 alleles were observed, respectively. Low molecular weight glutenin subunits (LMW-GS) displayed similar polymorphism, as 4, 9 and 3 alleles were identified at loci Glu-A3, Glu-B3 and Glu-D3, respectively. A total of 52 patterns resulted from the genetic combination of the alleles encoding at the six glutenin loci. This led to a significantly higher Nei coefficient of genetic variation in Glu-1 and Glu-3 loci (0.54). The Algerian hexaploid wheats exhibited allelic variation in HMW and LMW glutenin subunit composition and the variation differed from that of hexaploid wheats of other countries. The presence of high quality alleles in glutenin loci have led the Algerian wheat cultivars to be considered as an asset in breeding programs aimed for wheat quality.

Deletion of the low-molecular-weight glutenin subunit allele Glu-A3a of wheat (Triticum aestivum L.) significantly reduces dough strength and breadmaking quality.

BackgroundLow-molecular-weight glutenin subunits (LMW-GS), encoded by Glu-3 complex loci in hexaploid wheat, play important roles in the processing quality of wheat flour. To date, the molecular characteristics and effects on dough quality of individual Glu-3 alleles and their encoding proteins have been poorly studied. We used a Glu-A3 deletion line of the Chinese Spring (CS-n) wheat variety to conduct the first comprehensive study on the molecular characteristics and functional properties of the LMW-GS allele Glu-A3a.ResultsThe Glu-A3a allele at the Glu-A3 locus in CS and its deletion in CS-n were identified and characterized by proteome and molecular marker methods. The deletion of Glu-A3a had no significant influence on plant morphological and yield traits, but significantly reduced the dough strength and breadmaking quality compared to CS. The complete sequence of the Glu-A3a allele was cloned and characterized, which was found to encode a B-subunit with longer repetitive domains and an increased number of α-helices. The Glu-A3a-encoded B-subunit showed a higher expression level and accumulation rate during grain development. These characteristics of the Glu-A3a allele could contribute to achieving superior gluten quality and demonstrate its potential application to wheat quality improvement. Furthermore, an allele-specific polymerase chain reaction (AS-PCR) marker for the Glu-A3a allele was developed and validated using different bread wheat cultivars, including near-isogenic lines (NILs) and recombinant inbred lines (RILs), which could be used as an effective molecular marker for gluten quality improvement through marker-assisted selection.ConclusionsThis work demonstrated that the LMW-GS allele Glu-A3a encodes a specific LMW-i type B-subunit that significantly affects wheat dough strength and breadmaking quality. The Glu-A3a-encoded B-subunit has a long repetitive domain and more α-helix structures as well as a higher expression level and accumulation rate during grain development, which could facilitate the formation of wheat with a stronger dough structure and superior breadmaking quality.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0367-3) contains supplementary material, which is available to authorized users.

Evaluation of genetic variations at glutenin loci in Korean wheat landraces using allele-specific DNA markers

The allelic variations at glutenin loci could significantly affect the bread baking quality, and specific glutenin alleles might be closely associated with greater gluten strength, which, in turn, is related to superior bread baking quality. In this study, allelic variations at Glu-1, Glu-A3 and Glu-B3 loci were evaluated in 222 Korean wheat landraces using gene-specific polymerase chain reaction (PCR) markers. Ten alleles were identified at Glu-1 loci. Glu-A1c, Glu-B1b, and Glu-D1a or Glu-D1f alleles were predominantly found at the respective loci and their frequencies were 86.5, 87.8 and 96.9 %, respectively. Seven Korean wheat landraces carried the Glu-D1d allele, and only one Korean wheat landrace (IT173162) achieved 10 points for the Glu-1 score. Fifteen alleles were identified at Glu-A3 and Glu-B3 loci; Glu-A3c and Glu-B3d or Glu-B3i alleles were commonly found at the respective loci and their frequencies were 77.0, 33.3 and 37.8 %, respectively. Glu-B3 alleles exhibited the highest genetic diversity than other alleles, while Glu-B1 and Glu-A1 alleles exhibited the lowest genetic diversity than other alleles. Twenty Korean wheat landraces had the Glu-A3d and Glu-B3b, Glu-B3d, Glu-B3f, Glu-B3g or Glu-B3i alleles, which were correlated with superior bread baking quality. Among these wheat lines, two (IT59787 and IT236544) carried the Glu-D1d allele.