Characterization Of Novel Fast ω-gliadin Genes In Wheat And Its Relative Species And Their Affection Of Dough Quality And Sensitization

Wheat is an important crop in the world and they are the mainly source of food for people living in temperate regions. However, wheat is one of the major food allergies, which can induce a variety of immune responses such as celiac disease(Celiac Disease), asthma baker(Baker’s asthma), wheat-dependent-exercise-induced anaphylaxis(Wheat dependent-exercise induced anaphyxis, WDEIA) etc. Among them, WDEIA is considered to be a serious allergic reaction induced by fast ω-gliadin. However, the knowledge of fast ω-gliadin were limited. In this study, we cloned the fast ω-gliadin genes from wheat and its relative species, analyzes the molecular structure, sensitization mechanisms and the effect to the dough quality, the main results are as follows:1. Fast ω-gliadins were widely exist in wheat and its relative species. Different with the previous studies, the first three amino acids of N-terminal in the present study were SRL, TRQ, GRL, SRP, NRL or SRM. In addition to this, their molecular weight less than the reported ω-gliadin. These protein in the molecular structure includes a signal peptide, N-terminal, C-terminal and repeat region, which determines the size of the repeat region of the protein size. By comparing primary structure of the protein, we found there are a lot of Ig E-binding antigenic determinants in these proteins may be able to induce WDEIA. Among the highest content of Ig E-binding epitope sequence QQFPQQQ.2. Using the E. coli expression, were obtained four purified gliadins which are α-, γ- slow ω- and fast ω-gliadin. Then 50 mg, 100 mg and 150 mg purified proteins incorporation to the base flour, respectively and analysis the change of the dough properties. The results showed that α- and γ- gliadin showed more important to dough quality than ω-gliadins.3. Balb/c mice were sensitized by intraperitoneal injection the purified α-, γ-, slow ω-and fast ω-gliadins to analyze their differences in the sensitization. The results showed that there were no significant differences in sensitizing capacity between α-gliadin, γ-gliadin, slow ω-gliadin and fast ω-gliadin. Interactive reaction indicated that α-gliadin, γ-gliadin, slow ω-gliadin with fast ω-gliadin specific serum can produce high levels of Ig E rather fast ω-gliadin and α-gliadin, γ-gliadin, specific serum slow ω-gliadin are unable to produce high levels of Ig E, presumably fast ω-gliadin They are considered is a major allergen may be due to the excitation phase of allergy, Ig E detected mainly fast ω-gliadin-specific Ig E result.4. Evolutionary analysis showed that fast ω-gliadins and slow ω-gliadins were in two different branches of the phylogenetic tree, their divergence time was about 21.64 MYA, indicating that these two types of ω-gliadin have different evolutionary routes. Numbers of non-synonymous substitutions(Ka) and synonymous(Ks) substitutions per site were calculated among complete coding regions of fast ω-gliadin genes. The results indicated that fast ω-gliadin genes may be subject to a low selection pressure.