Analysis of HMW glutenin subunits encoded by chromosome 1A of bread wheat (Triticum aestivum L.) indicates quantitative effects on grain quality

Abstract

A gene encoding the high-molecular-weight (HMW) subunit of glutenin 1Ax1 was isolated from bread wheat cv Hope. Comparison of the deduced amino acid sequence with that previously reported for an allelic subunit, 1Ax2(*), showed only minor differences, which were consistent with both subunits being associated with good bread-making quality. Quantitative analyses of total protein extracts from 22 cultivars of bread wheat showed that the presence of either subunit 1Ax1 or 1Ax2(*), when compared with a null allele, resulted in an increase in the proportion of HMW subunit protein from ca. 8 to 10% of the total. It is suggested that this quantitative increase in HMW subunit protein may account for the association of 1Ax subunits with good quality.

Genomic regions influencing gene expression of the HMW glutenins in wheat

“…Storage proteins, glutenins and gliadins, are synthesized in the endosperm during the grain-filling period; they comprise 90% of the protein in the wheat grain (Huebner and Wall 1974;Pike and MacRitchie 2004). High molecular weight (HMW) glutenin subunits each contribute about 2% of the total seed protein (Payne et al 1984;Halford et al 1992) and contribute the unique elastic properties and quality of bread dough.…”

The 1Dx5 high molecular weight subunit gene from wheat in transgenic maize

“…Lines that have 5 HMW glutenin subunit genes expression contain about 10% of the protein in the form of HMW glutenin subunits. Each HMW glutenin subunit contributes about 2% of the total grain protein (Halford et aL 1992). The HMW glutenin proteins in wheat endosperm play an important role in bread-making quality (Payne et al 1980).…”

“…Gupta and MacRitchie (1994) reported that the lDx5-lDylO HMW glutenin subunits had a greater effect on dough strength than !Dx2-lDyl2 HMW glutenin subunits. Halford et al (1992) reported that the lAxl HMW glutenin subunit is also associated with good quality of bread wheat flour.…”

“…The first plasmid, named pHMWIDxS, is derived from pUC9 and contains an 8.7 kb £coRI genomic DNA fragment from hexaploid bread wheat that includes the 1DX5 coding sequence , 3.2 kb of 5' flanking sequence and 1.2 kb of 3' flanking sequence (Halford et al 1992). The construct pBAR184 consists of the maize ubiquitin promoter, first exon, and first intron, which drives the Streptomyces hygroscopicus bar gene with the Agrobacterium tumefaciens nos terminator (Frame et al, 2000).…”

“…The Glu-IDx5 gene from hexaploid wheat is contained on an 8.7 kb EcoRI genomic DNA fragment that includes the Glu-lDx5 coding sequence ), 3.2 kb of 5' flanking sequence and 12 kb of 3* flanking sequence (Halford et aL 1992). The Glu-IDx5 gene encoding the 1DX5 high molecular weight glutenin subunit kernel storage protein that is specifically expressed only in wheat endosperm, and this protein is significantly responsible for the elasticity of wheat dough.…”