Characterization of gluten proteins and celiac disease-related immunogenic epitopes in the Triticeae: cereal domestication and breeding contributed to decrease the content of gliadins and gluten

Abstract

Wheat proteins are important for the physico-chemical properties of bread-dough and contribute to the protein intake in the human diet. In certain individuals, an immunological reactivity of the gluten protein family is strongly implicated in the etiology of celiac disease (CD) and non-celiac wheat sensitivity (NCWS). There is evidence that gluten-related disorders have increased in frequency in recent years. Gluten proteins were characterized and quantified by reversed-phase high-performance liquid chromatography (RP-HPLC) while the occurrence of CD immunogenic epitopes was searched in the gliadin sequences of Triticeae within the NCBI database. We have observed a tendency toward low content of gliadins in cultivated species compared to that of the wild ancestors in all Triticeae members. Regarding the glutenin subunits, there was no clear trend, but levels tended to be higher in cultivated species. Thousand-kernel weight is higher for domesticated and cultivated species. Quantification of DQ2- and DQ8-restricted epitopes in gliadin sequences showed a great variability in the number of CD epitopes per species and genome. A higher frequency of immunnogenic epitopes was found to be associated with genomes of the DD, BBAADD, and RR type. Durum wheats tend to have a lower content of gluten and CD immunogenic epitopes. Cultivated barley could be an alternative cereal with low immunogenic epitopes and low gluten. The results reported in this study suggest that domestication and breeding have contributed to a decrease in the content of gliadins and total gluten in the Triticeae species over time.