Molecular characterization of the IgE-binding epitopes in the fast ω-gliadins of Triticeae in relation to wheat-dependent, exercise-induced anaphylaxis

• We cloned 66 novel fast ω-gliadin genes from Triticeae.
• The genes could be classified into the six subclasses according to the N-terminal domain.
• The deduced fast ω-gliadins contained IgE-binding epitopes.
• Fast ω-gliadins and ω1,2-gliadins were separated into two groups in evolutionary analysis.

Fast ω-gliadins were minor components of wheat storage proteins but a major antigen triggering allergy to wheat. Sixty-six novel full-length fast ω-gliadin genes with unique characteristics were cloned and sequenced from wheat and its relative species using a PCR-based strategy. Their coding regions ranged from 177 bp to 987 bp in length and encoded 4.28 kDa to 37.56 kDa proteins. On the base of first three deduced amino acids at the N-terminal, these genes could be classified into the six subclasses of SRL-, TRQ-, GRL-, NRL-, SRP- and SRM-type ω-gliadin genes. Compared by multiple alignments, these genes were significantly different from each other, due to the insertion or deletion at the repetitive domain. An analysis of the IgE-binding epitopes of the 66 deduced fast ω-gliadins demonstrated that they contained 0–24 IgE-binding epitopes. The phylogenetic tree demonstrated that the fast ω-gliadins and slow ω-gliadins were separated into two groups and their divergence time was 21.64 million years ago. Sequence data of the fast ω-gliadin genes assist in the study of the origins and evolutions of the different types of ω-gliadins while also providing a basis for the synthesis of monoclonal antibodies to detect wheat antigen content.