*debbie.laudencia@usda.gov

The gluten protein composition is a major determinant of the technological and nutritional properties of wheat-derived food products. The same proteins in gluten, however, can trigger several human health-related risks like wheat-dependent exercise induced anaphylaxis (WDEIA) and celiac disease. WDEIA is an IgE-mediated food allergy that is triggered by ingestion of wheat combined with certain cofactors like exercise, alcohol or non-steroidal anti-inflammatory drugs.

Allergic response can range from hives, difficulty in breathing, low blood pressure, angioedema, to anaphylaxis. The omega-5 gliadin, one of the proteins in gluten, is a major allergen responsible for WDEIA. To develop wheat lines with reduced allergenicity we generated and screened ethyl-methyl sulfonate and fast neutron radiation (FNR) mutagenized populations of a commercial variety of bread wheat (cv Summit) for the presence or absence of gluten proteins.

We identified several independent mutations for each of the 12 loci that encode gluten genes (Glu-1, high-molecular weight glutenin subunits; Glu-3, low-molecular weight glutenin subunits; Gli-1, omega, and gamma gliadins; and Gli-2, alpha gliadins). Exome capture assays using the ProEnSeq platform identified 143 glutenin and gliadin genes in the Summit genome, more than half of which are pseudogenes.

The in silico derived protein sequences of glutenin and gliadin genes surveyed for the presence of the 11 epitopes reported for WDIEA showed that 96 epitopes are in seven of the active gluten genes, 92 of which were on the three omega gliadin genes encoded by Gli-1B locus.

Mapping of the FNR induced mutation in Glu-3B-S225E line identified a 2 Mb deletion of Gli-1B/Glu-3B loci that removed 92 of the of the 96 WDEIA epitopes identified. Grain protein content, kernel weight, gluten-index and bread volume of Glu-3B-S225E was not significantly different from wild type. Hypoallergenic elite bread wheat lines with suitable agronomic traits can be used for healthier wheat products including plant-based meat alternatives.