Abstract
A set of eight SNP markers was developed to facilitate the early selection of HMW-GS alleles in breeding programmes. In bread wheat (Triticum aestivum), the high molecular weight glutenin subunits (HMW-GSs) are the most important determinants of technological quality. Known to be very diverse, HMW-GSs are encoded by the tightly linked genes Glu-1-1 and Glu-1-2. Alleles that improve the quality of dough have been identified. Up to now, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of grain proteins is the most widely used for their identification. To facilitate the early selection of HMW-GS alleles in breeding programmes, we developed DNA-based molecular markers. For each accession of a core collection (n = 364 lines) representative of worldwide bread wheat diversity, HMW-GSs were characterized by both genotyping and SDS-PAGE. Based on electrophoresis, we observed at least 8, 22 and 9 different alleles at the Glu-A1, Glu-B1 and Glu-D1 loci, respectively, including new variants. We designed a set of 17 single-nucleotide polymorphism (SNP) markers that were representative of the most frequent SDS-PAGE alleles at each locus. At Glu-A1 and Glu-D1, two and three marker-based haplotypes, respectively, captured the diversity of the SDS-PAGE alleles rather well. Discrepancies were found mainly for the Glu-B1 locus. However, statistical tests revealed that two markers at each Glu-B1 gene and their corresponding haplotypes were more significantly associated with the rheological properties of the dough than were the relevant SDS-PAGE alleles. To conclude, this study demonstrates that the SNP markers developed provide additional information on HMW-GS diversity. Two markers at Glu-A1, four at Glu-B1 and two at Glu-D1 constitute a useful toolbox for breeding wheat to improve end-use value.
Highlights
Wheat is one of the three most important crops in the world with production of about 729 million tonnes in 2014
We developed a series of PCR-based assays to readily identify wheat high-molecular-weight glutenin subunits (HMW-GS) based on competitive annealing of primers to single nucleotide polymorphism (SNP) using the KASP approach (Semagn et al 2014)
The HMW-GS of 364 accessions were identified by SDS-PAGE profiling and by molecular markers
Summary
Wheat is one of the three most important crops in the world with production of about 729 million tonnes in 2014 (http://faostat3.fao.org). In this context, wheat includes tetraploid species (2n = 28) such as durum wheat (Triticum turgidum spp. durum) and hexaploid species (2n = 42) such as bread wheat (T. aestivum spp. aestivum). Wheat is a major component of the human diet worldwide, often being the main source of energy. Wheat is an important plant source of protein providing on average 20% of the total protein in the human diet. Each type of wheat end-product requires particular qualities for processing that are mainly based on the properties of dough, determined by unique combinations of cohesiveness and viscoelasticity due to gluten. While gluten is necessary for processing wheat-based products, it triggers gluten-related disorders in humans, like allergies, coeliac disease and non-coeliac gluten sensitivity (Sapone et al 2012)
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