Wheat glutenin subunits and dough elasticity: findings of the EUROWHEAT project

Detailed studies of wheat glutenin subunits have provided novel details of their molecular structures and interactions which allow the development of a model to explain their role in determining the visco-elastic properties of gluten and dough. The construction and analysis of near-isogenic and transgenic lines expressing novel subunit combinations or increased amounts of specific subunits allows differences in gluten properties to be related to the structures and properties of individual subunits, with potential benefits for the production of cultivars with improved properties for food processing or novel end user

Variations in yield and gluten proteins in durum wheat varieties under late-season foliar versus soil application of nitrogen fertilizer in a northern Mediterranean environment

BACKGROUND: With the increasing demand for high-quality foodstuffs and concern for environmental sustainability, late-season nitrogen (N) foliar fertilization of common wheat is now an important and widespread practice. This study investigated the effects of late-season foliar versus soil N fertilization on yield and protein content of four varieties of durum wheat, Aureo, Ariosto, Biensur and Liberdur, in a three-year field trial in northern Italy. RESULTS: Variations in low-molecular-weight glutenins (LMW-GS), high-molecular-weight glutenins (HMW-GS) and gliadins were assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). It was found that N applied to the canopy did not improve protein rate compared with N application to the soil (general mean 138mg g 121), but moderately increased productivity in the high-yielding varieties Liberdur and Biensur (three-year means 7.23 vs 7.13 and 7.53 vs 7.09 t ha 121 respectively). Technological quality was mainly related to variety choice, Aureo and Ariosto having higher protein rates and glutenin/gliadin ratios. Also found was a strong \u2018variety 7 N application method\u2019 interaction in the proportions of protein subunits within each class, particularly LMW-GS and gliadins. A promising result was the higher N uptake efficiency, although as apparent balance, combined with higher HMW/LMW-GS ratio in var. Biensur. CONCLUSION: Late-season foliar N fertilization allows N fertilizer saving, potentially providing environmental benefits in the rainy climate of the northern Mediterranean area, and also leads to variety-dependent up-regulation of essential LMW-GS and gliadins. Variety choice is a key factor in obtaining high technological quality, although it is currently associated with modest grain yield. This study provides evidence of high quality in the specific high-yielding variety Biensur, suggesting its potential as a mono-varietal semolina for pasta production

The influence of long-term inputs of catch crops and cereal straw on yield, protein composition and technological quality of a spring and a winter wheat

Under conditions of restricted nitrogen (N) input such as in organic farming systems, crop N uptake must rely on N mineralised from applied animal manure, crop residues and native soil organic matter. Scarcity of N may impede the production of quality grain for bread production, and input and retention of N in soil are therefore important parameters for soil fertility. Toretain N in the crop-soilsystem, catch crops may be grown in breaks between main crops where they provide a significant sink for N mineralised in late summer and autumn (Thomsen, 2005). In corporation of straw may likewise retain mineralised N by microbial immobilisation (Christensen, 1986) and will also directly add to the N mineralisation potential when the N supplied in the straw accumulates (Thomsen & Christensen, 2004). Under northern European conditions, winter wheat may generally be of lower quality than spring wheat, but winter wheat has a higher yield potential. When the N uptake is mainly based on N mineralised from either applied or indigenous soil organic matter, however, this may even out the quality difference between winter and spring wheat as the longer growing season of winter wheat may boost its N utilisation. Growing conditions are highly important for protein quantity whereas main lygenetic factors influence protein composition (Amesetal., 1999; Luoetal., 2000). Wheat grain proteins have been classified as albumins, globulins, gliadins and glutenins on the basis of their solubility (Osborne, 1907). Reverse-phase (RP) high performance liquid chromatography (HPLC) allows the quantitative determination of these different flour protein groups together with single proteins (α5-, α1,2-, α-, γc-type gliadins, x- and γ-type high (HMW) and low (LMW) molecular weights subunits of glutenin) (Wieser & Seilmeier, 1998). The proteins can also be divided into polymers (glutenins) or monomers (gliadins, albumins, globulins) based on their aggregating properties. The polymeric proteins are critical for governing wheat flour processing properties, and their quantity and size distribution reliably measured by size-exclusion (SE) HPLC techniques have been shown to be important indicators of baking quality (Dachkevitch & Autran, 1989; Bateyetal., 1991). The aim of this study was to examine whether wheat yield and baking quality determined by chromatographic techniques together with rheological and chemical quality measurements could be improved by combining agronomic strategies consisting of wheat cultivars and long-term organic matter inputs. The variables tested were (A) a winter wheat and a spring wheat cultivar, (B) three catch crop strategies and (C) four straw incorporation rates

Opportunities in Tajikistan to breed wheat varieties resistant to seed-borne diseases and improved baking quality

Wheat seed-borne diseases and options for improving baking quality of wheat, as well as the role of genotypes for breeding to achieve high yield and quality are the key issues discussed in this introductory paper. The importance of wheat for Tajikistan and how to achieve food security goals in the country is also elucidated. Wheat seed-borne diseases are caused mostly by fungi. Loose Smut (Ustilago tritici), Common Bunt (Tilletia laevis and T.caries), Karnal Bunt (T.indica), Dwarf Bunt (T.controversa) and Black point (Alternaria spp., Bipolaris sorokiniana etc.) are all seed-borne diseases that are economically and regulatory important for Tajikistan, and these are therefore discussed in detail. The peculiarities of Tajik bread and requirements to the grain quality are also highlighted

Some quality characteristics of selected durum wheat (Triticum durum) landraces

Durum wheat (Triticum durum) is primarily used for the production of high-quality pasta products because of its certain superior characteristics. Wheat landraces are locally adapted diverse populations evolved through natural selection and are invaluable genetic resources for breeding programs. The search for new genetic resources all around the world has been underway to develop high-quality durum wheats. The purpose of this study was therefore to determine the pasta quality-associated characteristics of 12 durum wheat landraces (Bağacak, Beyaziye, İskenderiye, Sorgül, Karakılçık, Beyaz Buğday, Ağ Buğdayı, Bintepe, Havrani, Çalıbasan, Hacı Halil, and Akçakale) compared to 2 wellestablished high-quality durum wheat cultivars, Kyle and Zenit. Protein content and quality, pigment content, activities of oxidative enzymes (lipoxygenase, polyphenol oxidase, and peroxidase), kernel size, and endosperm vitreousness were measured as the major quality parameters. The landraces had significant differences (P < 0.05) in their quality characteristics. Of the landraces, Akçakale, Havrani, and Çalıbasan were found to be quite promising for the processing of so-called al dente cooking pasta products, as judged by their elevated protein quantity and gluten quality. With respect to pigment content and oxidative enzymes that are central to the bright yellow color of pasta products, however, the landraces Havrani, Hacı Halil, and Sorgül were found to have great potential. In brief, several landraces have potential for high-quality pasta processing, while a few others can be used for breeding purposes

Infuence of the year and HMW glutenin subunits on end-use quality predictors if bread wheat waxy lines

The effects of environment and the high molecular weight glutenins on some quality properties (sedimentation volume, % protein content, and starch pasting viscosity) of bread wheat mutant waxy lines were evaluated. Thirty-eight 100% amylose-free F 2 derived F 6 and F 7 lines were used. The results indicated that the environment did not influence sedimentation volume, mixograph parameters and starch viscosity parameters of waxy flour. Variation in the % protein content was determined mainly by the environment. The sedimentation volume and the mixograph peak development time were influenced by the variation at over expression of Bx7 and the mixograph peak development time was influenced by the Glu-D1 locus. One starch viscosity parameter, time to peak viscosity, was influenced by variation at the Glu-A1 locus. This parameter is significantly lower in the waxy lines than the parent line, which shows the influence of the waxy loci. No significant correlation was observed for sedimentation volume, mixograph parameters, protein content and viscosity parameters of waxy line

Allelic variation in HMW glutenin in Spanish wheat landraces and their relationship with bread quality

The allelic variation of high molecular weight glutenins as principal determinants of bread quality has been analyzed in 165 Spanish wheat ( Triticum aestivum ssp. vulgare L.) landraces provided by the Plant Genetic Resources Centre. The identification by standard electrophoresis techniques has been supported by a new PCR screening method, allowing the identification of the 2•• glutenin subunit from the Glu-A1 locus in some landraces. The relation of high molecular weight glutenins and bread quality has been evaluated by SDS-sedimentation tests and mixographs. A positive influence on quality has been found for the 2•• glutenin subunit from the Glu-A1 locus, pairs 7 + 8 and 13 + 16 from the Glu-B1 locus, and pair 5 + 10 from the Glu-D1 locus. The presence of a wide range of values for quality traits in landraces with the same high molecular weight glutenin composition points to the possible influence of other prolamins such as the low molecular weight glutenins. Their influence on bread quality will be assessed in future studies. A complete description of the high molecular weight glutenin composition and quality values of all the landraces analyzed in this study is provided for use in wheat breeding program

Assessment of the Glutenin Subunits Diversity in a Durum Wheat (T. turgidum ssp. durum) Collection from Morocco

Landraces and old wheat cultivars display great genetic variation and constitute a valuable resource for the improvement of modern varieties, especially in terms of quality. Gluten quality is one of the major determinants of wheat quality, and it is greatly influenced by variation in the high molecular weight and low molecular weight glutenin subunits (HMW-GS and LMW-GS). Identification of novel allelic variants for either of the two groups of the gluten-forming proteins could greatly assist in the improvement of wheat gluten quality. In the present study, the allelic composition of the HMW- and LMW-GS of ninety-five durum wheat accessions was evaluated. These accessions included Moroccan cultivars and landraces and North American cultivars and were all conserved in the National Gene Bank from Morocco. In total, 20 cataloged alleles and 12 novel alleles were detected. For the HMW-GS, two alleles were found at the Glu-A1 locus, and seven different allelic variants were identified at the Glu-B1 locus. Among them, two alleles were new (alleles Glu-B1cp and co). Additionally, two of the analyzed accessions exhibited the Glu-D1d allele, suggesting the presence of the Glu-D1 locus introgression. For the LWM-GS, eight, ten and two alleles were identified at the Glu-A3, Glu-B3 and Glu-B2 loci, respectively. Among them, two new allelic variants were identified at the Glu-A3 locus, and seven new allelic variants were identified at the Glu-B3 locus. Overall, the Moroccan landraces exhibited a greater genetic diversity and a greater number of glutenin alleles compared to the Moroccan and North American durum wheat cultivars. The novel germplasm and glutenin alleles detected in this study could contribute to the improvement of durum wheat quality and the expansion of modern durum wheat genetic diversity

A Study of the Rheological Properties and Gluten Protein Components Associated with Enhanced Baking Quality in Durum Wheat (Triticum turgidum L. var. durum)

Durum wheat (Triticum turgidum L. var. durum, 2n = 4x = 28, AABB genomes) is used predominantly for semolina and pasta products, but there is increasing interest in using durum for bread-making to provide alternative markets during periods of overproduction. The goal of this study was to characterize the bread-making quality of durum wheat cultivars and emmer (Triticum turgidum L. var. dicoccum, 2n = 4x = 28) derived breeding lines derived from crosses of durum wheat with an Emmer land race ‘97Emmer19’ from Iran. Emmer-derived breeding lines were evaluated along with three high quality bread wheat (Triticum aestivum L., 2n = 6x = 42, AABBDD genomes) cultivars and seven durum wheat cultivars across three environments in replicated yield trials in the 2005 and 2006 growing seasons. Four 1AS.1AL-1DL translocation lines which carry the Glu-D1d allele [high molecular weight glutenin subunit (HMW-GS) pair 1Dx5+1Dy10] from chromosome 1D of bread wheat were also evaluated. In general, durum wheat cultivars with elevated gluten strength and/or increased dough extensibility were noted to have higher loaf volume (LV) than those with weaker gluten. The 1AS.1AL-1DL translocation line ‘L252’ carrying the LMW-1 banding pattern had better dough mixing stability and LV than the translocation lines with the LMW-2 banding pattern. The 1AS.1AL-1DL translocation lines had higher grain protein concentrations (GPC), but the lowest loaf volumes of all the lines tested. These translocation lines also exhibited unappealing external loaf quality (loaf shape and appearance) and poor internal loaf quality (crumb structure). Variation in bread-making quality attributes were observed among durum genotypes. ‘97Emmer19’ exhibited higher LV than all the durum wheats evaluated and approached the loaf volume achieved with the bread wheat cultivar ‘AC Superb’. Breeding lines derived from crosses of ‘97Emmer19’ to strong gluten durum cultivars (‘WB881’ or ‘AC Navigator’) had higher LV than those of the durum checks. ‘97Emmer19’ carried Glu-A1a* (HMW-GS 1Ax1) and the progeny carrying that allele generally exhibited higher loaf volumes. Durum wheat genotypes expressing the Glu-B1d (HMW-GS pair Bx6+By8) allele exhibited better overall bread-making quality compared with those expressing the Glu-B1b (HMW-GS pair Bx7+By8) allele. The durum cultivar ‘Arcola’ and the emmer-derived breeding line ‘2000EB4’, showed higher alveograph extensibility (L) values than did the bread wheat check ‘AC Barrie’. The durum wheat genotypes (with the exception of ‘Stewart-63’) and emmer-derived breeding lines exhibited better dough extensibility than the USDA-ARS 1AS.1AL-1DL translocation lines. These results indicate that there is potential to select for genotypes with improved baking quality in durum breeding programs