Comparative study of the alpha-gliadin genes in diploid and polyploid genomes of wheat

Abstract

Hexaploid bread wheat originated from the spontaneous hybridization of tetraploid wheat (Triticum turgidum, AABB) with a diploid progenitor, Aegilops tauschii (DD). The tetraploid wheat was from the hybridization of two diploid progenitors, Triticum urartu (AA) and an unconfirmed specie, which donated the BB genome. Gliadins are gluten proteins associated with celiac disease (CD), a food-sensitive enteropathy caused by the ingestion of gluten from wheat, barley and rye. The most toxic peptide is on an α-gliadin, which contains six overlapping T-cell epitopes with high stimulatory properties. The genes encoding α-gliadins are controlled by the Gli-2 loci (Gli-A2, Gli-B2, and Gli-D2) present on the short arms of the group 6 chromosomes in bread wheat. A collection of wheats encompassing the ancestor diploid genomes (AA, BB and DD) and the derived hexaploid (AABBDD) was studied to analyse the evolution of α-gliadin genes during the polyploidization phenomenon.