Analysis of Structural Homology and Evolutionary Relationships among Gamma- and Omega-gliadins in Different Wheat Species and Varieties

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Background: Gamma-and omega-gliadins are major components of gluten in wheat and can trigger allergic reactions and gluten intolerance. An increase in the number of motifs in their sequences correlates with a rise in toxic epitopes, leading to a stronger immune response. Evaluating the structural homology of gliadins across different wheat species and varieties can help identify toxic epitopes, which may be edited to neutralize their effects. This study aimed to evaluate the structural homology, evolutionary relationships and presence of toxic epitopes in various wheat species and varieties. Methods: Multiple sequence alignment using the ClustalW algorithm (BLOSUM62 matrix) in the Ugene program was used to identify structural differences between gamma- and omega-gliadins. The alignment results were evaluated based on percentage identity, scores and the presence of homologous regions. Phylogenetic analysis was performed using the maximum likelihood method with the JJT+G+F model for gamma-gliadins and the LG+G+F model for omega-gliadins, using the MEGA11 software with bootstrap support. Result: Gamma-gliadins had a high degree of similarity across different wheat species and varieties, while omega-gliadins showed more variability and were less conserved. Toxic epitopes linked to celiac disease were most commonly found in gamma-gliadins of T. aestivum and T. dicoccoides Atlit2015, with fewer in T. monococcum clone 45-L024585. The unique amino acid composition of omega-gliadins was associated with diverse toxic epitope variations. T. aestivum Chinese Spring D2 and D3 contained more toxic epitope segments related to celiac disease, whereas no presumed toxic epitopes were detected in T. monococcum DV80. The obtained data can be used for genetic editing aiming to create wheat varieties that include allergen-neutral gliadins by reducing the repetitive motifs of celiac disease epitopes.