Identification of Genome Specific Sequence Motifs in α- Gliadins and Wheat Accessions with Less Celiac Disease Epitopes

Among gliadins, α-gliadins are important active proteins in triggering celiac disease in human beings owing to the presence of toxic epitopes. A set of 177 α-gliadin gene sequences and the corresponding proteins were analyzed. Twenty accessions of hexaploids including 1, 14, and 5, respectively representing A, B, and D, with no intact CD-epitopes in α-gliadins, were identified. Twenty-two and 13 conserved motifs in non-repetitive domains NR1 and NR2, respectively, of α-gliadins differentiated all the amino acid sequences encoded by A genome of both diploids and hexaploids. Most of the amino acid sequences encoded by D genome (70 of 75 in hexaploids and 13 of 16 in diploids) could be identified by 22 amino acid motif. Large variations and lesser number of intact CDepitopes was observed for α-gliadins belonging to B genome. As compared to diploids, repeat length of polyglutamine repetitive domain QII of B genome was lower in hexaploids indicating loss of Q residues during evolution of hexaploid wheat. The information can be used in assigning any α-gliadin sequences onto A, B, and D genomes and identifying wheat accessions with lesser CD-epitopes. The result presented here will be useful for the wheat improvement programs aiming for the management of celiac disease in human beings.