Evaluation of alpha-gliadin celiac disease epitopes in some Aegilops species containing the D genome

Abstract Wheat gluten protein contains toxic peptides that trigger celiac disease in genetically susceptible individuals. These toxic peptides are primarily found in gliadin fractions, which are largely derived from the D subgenome of allohexaploid wheat. Aegilops species are valuable germplasm resources for wheat breeding. In this study, we analyzed the content and composition of alpha-gliadin CD epitopes in ten genotypes from five distinct species of the Aegilops genus: Aegilops tauschii , Aegilops crassa , Aegilops juvenalis , Aegilops cylindrica , and Aegilops ventricosa . This analysis was conducted using RNA sequencing of the main amplicon of alpha-gliadins that includes the most toxic CD peptides. Our results showed significant differences in the types and distribution patterns of identified CD epitopes across various species and accessions. All the canonical and the most toxic CD epitopes were detected in the studied Aegilops genotypes. However, the intact form of the 33-mer region was absent in all genotypes. Ae. ventricosa ‘AE 1511’ and Ae. juvenalis ‘AE 537’ exhibited the highest expression frequency for the p31-43 and DQ2.5-glia-α3 epitopes, categorizing them as the most toxic species. In contrast, Ae. crassa ‘TA1873’, Ae. cylindrica ‘AE 1658’, and Ae. crassa ‘AE 815’ showed the highest expression frequencies for DQ2.5-glia-α1a and DQ2.5-glia-α2, identifying them as the least toxic species. Our findings suggest that incorporating the D genome from Ae. crassa and Ae. cylindrica ‘AE 1658’ into wheat breeding programs might be a promising strategy for reducing gluten toxicity associated with celiac disease.