Allelic variation of gliadin-encoding genes in a collection of tetraploid wheat genotypes

Wheat is one of the main crops bred worldwide. Durum wheat, specifically, is a key element of the Mediterranean diet, representing an elite crop grown in Italy. Durum wheat nutritional and technological values are largely due to the grain protein content (GPC), a complex genetic trait strongly affected by environmental factors and management practices. In the last decades, several breeding programs have been focused on improving GPC by both traditional and innovative approaches. Among seed storage proteins, prolamins, including both gliadins and glutenins, represent the major component. These two classes of proteins are indeed responsible of gluten formation and confer the extensibility and elasticity to the dough. Besides being of crucial importance for both technological properties and rheological characteristics, prolamins, and especially gliadins, have been found to be major triggers for human health, as involved in a number of wheat consumption-related conditions, such as the celiac disease, non-celiac gluten sensitivity, defined as the onset of a variety of manifestations related to wheat, rye and barley ingestion, and wheat allergies, both due to wheat ingestion or inhalation (of flour or pollen). The identification of loci responsible for the gliadin expression, and particularly of polymorphism in the aforementioned genes, which could result in a lower immunogenic/toxic potential, could be of great importance in breeding programs. For this purpose, we screened a collection of tetraploid wheat genotypes for allelic variants of annotated gliadin genes in the durum wheat genome, in order to identify genetic resources available to breeders to improve wheat nutritional and technological properties. Phylogenetic analysis among different species of Triticum genus and an in silico expression data analysis may also be useful in the exploitation of the complex scenario of gliadin–glutenin interaction and gluten role in the adverse reactions due to wheat consumption.