The a-gliadin immunogenic complex in wheat

The a-gliadins present in wheat flour contain the most-immunogenic epitopes which are responsible for gluten intolerances. Previous studies on wheat were focused on individual epitopes but not on the protein fragments containing those epitopes. In this work a comprehensive study of the main fragment of a-gliadins containing immunogenic epitopes has been carried out. By using NGS technology, six types of a-gliadins were identified in diploid and polyploid wheats. We show that Type 1 a-gliadins, but not the other types, contain all the immunogenic peptides and epitopes. This Type 1 sequence underwent two independent rounds of small insertion events in the a-gliadin repetitive region giving rise to the most-toxic 33-mer peptide containing six overlapping epitopes in bread (hexaploid) wheat. These findings are important for CD and wheat breeding as we identify five types of a-gliadins that do not contain toxic epitopes.