The specific composition of the glutenins, the major components of gluten, determines to a great extent the gluten properties (strength and extensibility) and end-use quality of wheat genotypes. Glutenins are divided into high-molecular-weight glutenins (Glu-A1, Glu-B1 and Glu-D1 loci); and low-molecular-weight glutenins (Glu-A3, Glu-B3 and Glu-D3 loci). Allelic variation at each of these loci has been associated with changes in the above-mentioned traits in most studies. However, it is still unclear which locus contributes more and how important are the interactions between the glutenin loci, mainly because these studies often included a relatively limited number of genotypes.

In our study, the quality data of 4,623 grain samples derived from 2,550 genotypes and generated across 10 years by the CIMMYT bread wheat breeding program, was used to estimate the effect of the glutenin loci and their interactions on quality traits, including gluten strength and extensibility measured by the alveograph and bread-making quality. This is probably the largest study ever done on the effects of the glutenins on wheat quality. Different glutenins alleles and their interactions were associated with high or low values of the examined traits. The two combinations of glutenins associated with highest gluten strength loaf volume were Glu-A1a/Glu-B1i/Glu-D1d/Glu-A3c/Glu-B3g/Glu-D3b (N=30, alveograph W=353 J*10-4, loaf volume=845 mL) and Glu-A1a/Glu-B1f/Glu-D1d/Glu-A3c/Glu-B3d/Glu-D3b (N=36, alveograph W=338 J*10-4, loaf volume=873 mL).

The results obtained confirm the importance of such proteins on wheat quality variation and corroborate the usefulness of determining the glutenin profile to improve the selection efficiency for wheat quality in breeding programs.