A PCR-based method for discriminating between high molecular weight glutenin subunits Bx7 and Bx7* in Triticum aestivum L

The correct assignment of high molecular weight glutenin subunit variants is a key task in wheat breeding. However, the traditional analysis by protein electrophoresis is sometimes difficult and not very precise. This work describes a novel DNA marker for the accurate discrimination between the Glu-B1 locus subunits Bx7 and Bx7*. The analysis of one hundred and forty two bread wheat cultivars from different countries has highlighted a great number of misclassifications in the literature that could lead to wrong conclusions in studies of the relationship between glutenin composition and wheat quality

Down-Regulating γ-gliadins in bread wheat leads to non-specific increases in other gluten proteins and has no major effect on dough gluten strength.

Background Gliadins are a major component of gluten proteins but their role in the mixing of dough is not well understood because their contribution to wheat flour functional properties are not as clear as for the glutenin fraction. Methodology/Principal Findings Transgenic lines of bread wheat with γ-gliadins suppressed by RNAi are reported. The effects on the gluten protein composition and on technological properties of flour were analyzed by RP-HPLC, by sodium dodecyl sulfate sedimentation (SDSS) test and by Mixograph analysis. The silencing of γ-gliadins by RNAi in wheat lines results in an increase in content of all other gluten proteins. Despite the gluten proteins compensation, in silico analysis of amino acid content showed no difference in the γ-gliadins silenced lines. The SDSS test and Mixograph parameters were slightly affected by the suppression of γ-gliadins. Conclusions/Significance Therefore, it is concluded that γ-gliadins do not have an essential functional contribution to the bread-making quality of wheat dough, and their role can be replaced by other gluten protein

Desarrollo de nuevos marcadores de DNA para la identificación de gluteninas de alto peso molecular (HMW) en trigo

Las subunidades de gluteninas de alto peso molecular (HMW-GS) son las principales responsables de la calidad pandera del trigo (T. aestivum ssp vulgare L.). Su estudio se realiza por métodos electroforéticos en geles SDS-PAGE, habiéndose identificado así una gran cantidad de alelos distintos con diferente influencia en la calidad. Sin embargo, la correcta asignación de alelos puede ser a veces complicada usando sólo este método, por ello se están desarrollando marcadores basados en la secuencia de ADN que complementen el análisis electroforético y ayuden a la correcta discriminación alélica. En este trabajo se han desarrollado marcadores nuevos para diferenciar inequívocamente las subunidades 2¨ vs 2* del locus Glu-A1, y, la 7 vs 7* y la 7 vs 13 del locus Glu-B1

Nuevo locus que codifica la subunidad de glutenina C-LMW-5 en el cromosoma 6B de trigo panadero.

En el análisis genético de las prolaminas en granos F2 procedentes de dos cruzamientos entre cultivares de trigo panadero, se ha encontrado un estrecho ligamiento entre una subunidad de glutenina de bajo peso molecular (LMW) de tipo C y gliadinas codificadas por el locus Gli-B2 situado en el cromosoma 6B. Se ha denominado Glu-B6 al locus que codifica dicha glutenina C-LMW

Stacking HMW-GS transgenes in bread wheat: Combining subunit 1Dy10 gives improved mixing properties and dough functionality

We have determined the technological properties of four lines containing combinations of three HMW-GS transgenes, encoding HMW-GS 1Ax1, 1Dx5 and 1Dy10. These lines were produced by conventional crossing of three single transgenic lines of the bread wheat cultivar Anza that contains the endogenous HMW-GS pairs 1Dx2 + 1Dy12 and 1Bx7* + 1By8 and is null for the Glu-A1 locus. Consequently, the total number of HMW-GS ranged from 4 in the control line Anza to 7 in line T618 which contains all three HMW-GS transgenes. The lines were studied over two years using a range of widely used grain and dough testing methods. All lines with transgenic subunits showed higher levels of glutenin proteins than the Anza control, and these differences were highly significant for lines T616, T617 and T618, containing, respectively, the transgenes encoding HMW-GS 1Ax1 and 1Dy10, 1Dx5 and 1Dy10 and 1Ax1, 1Dx5 and 1Dy10. These increases in glutenin levels are compensated by lower levels of gliadins present in transgenic lines. These changes affected the ratio of polymeric to monomeric gluten proteins (poly:mono), the ratio of HMW-GS to LMW-GS (HMW:LMW) and the contents of individual 1Ax, 1Bx, 1By, 1Dx and 1Dy subunits. Transgenic lines expressing subunit 1Dy10 together with x-type subunits (T616, T617 and T618) were superior to line T606, which had only increases in x-type subunits. In particular, the combination of transgenic subunits 1Dx5 and 1Dy10 (line T617) gave better dough rheological properties than the other combinations of transgenic subunits. For example, dough development time and stability were increased by 3.5-fold and 8.5-fold, respectively, while the mixing tolerance index (MTI) was decreased by 3.3-fold in line T617 with respect to the control line. Alveograph analyses showed that all four transgenic combinations had increased P values compared to the Anza control but subunit 1Dx5 greatly reduced the extensibility (L). These results show that stacking HMW-GS transgenes by conventional crossing is a valid strategy for the improvement of wheat quality, with different effects being related to the different HMW-GS combination

Mapeo de QTLs asociados a calidad panadera en trigo blando.

La calidad panadera del trigo blando (Triticum aestivum ssp vulgare L.) es un carácter complejo controlado fundamentalmente por las prolaminas, proteínas del gluten. El principal objetivo de este estudio ha sido realizar un mapeo de QTLs relacionados con pará- metros de calidad para detectar nuevos loci implicados en este carácter. El material de estudio fue una colección de 79 RILs derivadas del cruce entre un trigo “soft” y uno “hard”. Los ensayos de campo se llevaron a cabo durante dos años. Se evaluó la calidad de la masa mediante el test de sedimentación, y parámetros del mixógrafo y del alveografo. Se construyó un mapa basado en SSRs y 7 loci de prolaminas. El análisis por CIM (Composite interval mapping) detectó un total de 20 QTLs distribuido en diez cromosomas y asociados con las variaciones en los parámetros de calidad. Los resultados confirmaron las investigaciones anteriores sobre la relación conocida entre los alelos de proteí- nas de reserva y la calidad de la masa, y se detectaron QTLs nuevos en los cromosomas 2A, 7A y 5B que serán el punto de partida para futuros proyecto

Mapeo de QTLs asociados a calidad panadera en trigo blando.

La calidad panadera del trigo blando (Triticum aestivum ssp vulgare L.) es un carácter complejo controlado fundamentalmente por las prolaminas, proteínas del gluten. El principal objetivo de este estudio ha sido realizar un mapeo de QTLs relacionados con pará- metros de calidad para detectar nuevos loci implicados en este carácter. El material de estudio fue una colección de 79 RILs derivadas del cruce entre un trigo “soft” y uno “hard”. Los ensayos de campo se llevaron a cabo durante dos años. Se evaluó la calidad de la masa mediante el test de sedimentación, y parámetros del mixógrafo y del alveografo. Se construyó un mapa basado en SSRs y 7 loci de prolaminas. El análisis por CIM (Composite interval mapping) detectó un total de 20 QTLs distribuido en diez cromosomas y asociados con las variaciones en los parámetros de calidad. Los resultados confirmaron las investigaciones anteriores sobre la relación conocida entre los alelos de proteí- nas de reserva y la calidad de la masa, y se detectaron QTLs nuevos en los cromosomas 2A, 7A y 5B que serán el punto de partida para futuros proyecto

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

Molecular characterization of Glu-B3 locus in wheat cultivars and segregating populations

Bread wheat quality constitutes a key trait for the demands of the baking industry as well as the broad consumer preferences. The role of the low molecular weight glutenin subunits (LMW-GS) with regard to bread quality is so far not well understood owing to their genetic complexity and to the use of different nomenclatures and standards for the LMW-GS assignment by different research groups, which has made difficult the undertaking of association studies between genotypes and bread quality. The development of molecular markers to carry out genetic characterization and allele determination is demanding. Nowadays, the most promising LMW gene marker system is based on PCR and high resolution capillary electrophoresis for the simultaneous analysis of the complete multigene family. The molecular analysis of the bread wheat Glu-B3 locus in F2 and F4:6 populations expressed the expected one-locus Mendelian segregation pattern, thus validating the suitability of this marker system for the characterization of LMW-GS genes in segregating populations, allowing for the successful undertaking of studies related to bread-making quality. Moreover, the Glu-B3 allele characterization of standard cultivars with the molecular marker system has revealed its potential as a complementary tool for the allelic determination of this complex multigene family

Análisis comparativo del potencial de siete variedades de triticale para usos agroenergéticos.

Se han realizado ensayos de campo durante 2008 y 2009 para evaluar la producción de biomasa seca y de los principales componentes celulósicos de la biomasa, y el rendimiento en grano de 7 variedades de triticale y 5 variedades de otros cereales (centeno, avena forrajera y trigo blando). Los centenos analizados, en particular la variedad híbrida ‘Picasso’, han sido los materiales más productivos, tanto en lo que respecta a su posible rendimiento energético, como en su condición de cereal para grano. No obstante, los triticales ‘Forricale’ y ‘Misionero’ han mostrado un buen potencial como cultivo agroenergé- tico, especialmente en condiciones climatológicas adversas. También destacan en cuanto a su posible utilización como variedades de doble uso: biocombustible y cereal-grano