Dissemination of the highly expressed Bx7 glutenin subunit (Glu-B1al allele) in wheat as revealed by novel PCR markers and RP-HPLC

Abstract

Increased expression of the high molecular weight glutenin subunit (HMW-GS) Bx7 is associated with improved dough strength of wheat (Triticum aestivum L.) flour. Several cultivars and landraces of widely different genetic backgrounds from around the world have now been found to contain this so-called 'over-expressing' allelic form of the Bx7 subunit encoded by Glu-B1al. Using three methods of identification, SDS-PAGE, RP-HPLC and PCR marker analysis, as well as pedigree information, we have traced the distribution and source of this allele from a Uruguayan landrace, Americano 44D, in the mid-nineteenth century. Results are supported by knowledge of the movement of wheat lines with migrants. All cultivars possessing the Glu-B1al allele can be identified by the following attributes: (1) the elution of the By sub-unit peak before the Dx sub-unit peak by RP-HPLC, (2) high expression levels of Bx7 (>39% Mol% Bx), (3) a 43 bp insertion in the matrix-attachment region (MAR) upstream of the gene promoter relative to Bx7 and an 18 bp nucleotide duplication in the coding region of the gene. Evidence is presented indicating that these 18 and 43 bp sequence insertions are not causal for the high expression levels of Bx7 as they were also found to be present in a small number of hexaploid species, including Chinese Spring, and species expressing Glu-B1ak and Glu-B1a alleles. In addition, these sequence inserts were found in different isolates of the tetraploid wheat, T. turgidum, indicating that these insertion/deletion events occurred prior to hexaploidization.

Identification and characterization of high-molecular-weight glutenin genes in Polish triticale cultivars by PCR-based DNA markers

“…The secalins, inherited from rye, are distinct from wheat storage proteins and not capable of forming gluten. The bread-making quality of bread wheat is mainly determined by the composition and quantity of gluten-forming storage proteins, in particular the high-molecular-weight glutenin subunits (HMW-GS) (Wieser et al1998;Butow et al 2003Butow et al , 2004. Various alleles of HMW glutenin genes are J Appl Genet 48(4), 2007, pp.…”

“…The presence of both wheat and rye HMW proteins in triticale, which appear in different amounts and additionally are often characterized by similar electrophoretic mobilities, interferes to a large extent with the identification of individual HMW subunits by using SDS-PAGE gels. Particularly, some functionally different HMW glutenin subunits, such as Bx7 vs. Bx7* or By8 vs. By8*, have similar relative electrophoretic mobilities and cannot be unambiguously identified by SDS-PAGE (Butow et al 2003(Butow et al , 2004.…”

Screening Selected Spring Wheat Cultivars for Productivity, Protein Content and the Glu-B1 Allele Using PCR

“…The bread-making quality of wheat is mainly determined by the composition and quantity of gluten-forming storage proteins, in particular the high-molecular-weight glutenin subunits (HMW-GS) (Butow, et al, 2003(Butow, et al, , 2004. Various alleles of HMW glutenin genes are particularly important for determining wheat gluten and dough elasticity .…”

Evaluación de la calidad funcional y sensorial en cultivares de Triticum aestivum ssp. vulgare y ssp. spelta en cultivo ecológico

“…Dada la importancia de las HMW-GS en la calidad de la masa, en los últimos años se han ido desarrollando oligonucleótidos específicos para amplificar mediante PCR (De Bustos et al, 2001;Ma et al, 2003;Butow et al, 2004;Lei et al, 2006;Gobaa et al, 2007;Ragupathy, 2008;Espí et al, 2012), y de esta manera poder diferenciar mejor las distintas HMW-GS que se visualizan mediante SDS-PAGE. Fuente: Payne et al (1984Payne et al ( , 1987, Pogna et al (1986) y Branlard et al (1992.…”

“…Estos autores asignaron puntuaciones de calidad a las diferentes HMW-GS, según la observación de su efecto en las pruebas de calidad panadera, permitiendo estimar la puntuación en fuerza panadera de una variedad o de una línea de trigo. Esta herramienta ha permitido a los mejoradores seleccionar utilizando la electroforesis SDS-PAGE en las líneas o las variedades deseadas (Tabla 5).Dada la importancia de las HMW-GS en la calidad de la masa, en los últimos años se han ido desarrollando oligonucleótidos específicos para amplificar mediante PCR (De Bustos et al, 2001;Ma et al, 2003;Butow et al, 2004;Lei et al, 2006;Gobaa et al, 2007 Sobre la influencia en la calidad panadera de las LMW-GS hay menos información, pero sí se ha encontrado que influyen significativamente (Gupta et al 1989; Gupta y McRitchie, 1994). El análisis de patrones de LMW-GS y su determinación alélica la iniciaron Gupta y Shepherd (1990).…”