The minimal amino acid sequences within wheat gluten proteins that elicit T-cell responses in CeD patients are designated as immunogenic epitopes. The amount of gluten consumed correlates with the incidence of CeD in prospective childhood studies, indicating that the quantity of ingested immunogenic epitopes may affect the onset of the disease. Gluten is composed of glutenin and gliadins proteins. Glutenins are critical for dough strength, but gliadins have the majority of the immunodominant epitopes and may be dispensable for dough strength and quality. Gliadin and glutenin genes are distributed in 9 main loci on the hexaploid wheat genome.
Two different wheat breeding strategies are followed to address research and breeding objectives. For the research objective, the loci without any known epitopes are being combined to generate ‘clean' genetic stocks that will be tested in CeD patients to confirm the complete elimination of immunogenic epitopes. For the breeding objective, deletions that eliminate the more immunogenic gliadins but not the glutenins are being combined to generate lines with adequate breadmaking quality and reduced immunogenicity.
Radiation-induced deletions, chemical-induced mutations, and CRISPR-edited mutations that eliminate gluten genes containing CeD epitopes have been identified. The genome of wheat variety Summit was sequenced and deletions of interest were mapped to this reference to identify which genes had been eliminated. RP-HPLC, immunoblots, and LCMS were used to characterize the proteomic profiles of the deletion lines.
Lines containing the individual gliadin and glutenin deletions as well as different deletion-
combinations were produced as a result of this study. By comparing genomic, transcriptomic, and proteomic data, the gluten profiles of each line have been characterized. These lines will be publicly available via GRIN-Global (https://www.grin-global.org/).
The genetic stocks with reduced CeD epitopes can be requested by food scientists, immunologists, and wheat breeders to assess their end-use quality and relative immunogenicity.