Characterization of α-gliadin alleles of Japanese wheat cultivars in relation to flour dough extensibility and celiac disease epitopes

Abstract

Alpha-gliadins are major seed storage proteins of wheat and are involved in dough extensibility, which is related to the end-use properties of flour. However, α-gliadin causes gluten-related diseases such as celiac disease (CD). To characterize the α-gliadin allele types of Japanese cultivars, PCR markers that detect the presence of each α-gliadin gene in Chinese Spring wheat were used to determine allele-types. We surveyed 95 accessions of the Japanese wheat core collection (JWC) and 22 commercial cultivars and found 2, 10, and 4 allele types at the loci Gli-A2, Gli-B2, and Gli-D2, respectively. According to the allele-type frequency, the α-gliadin alleles of JWC showed diversities comparable to those of foreign cultivars. Allele diversities were compared within four populations of JWC, classified by genome-wide single nucleotide polymorphisms. The degree of diversity of alleles reflected the population structures, except for high diversity of the allele-types at Gli-B2 in the classical varieties. The frequencies of alleles related to end-use were higher in newer varieties than in classical varieties and landraces. Allele types that dramatically decreased and increased CD epitopes were not found in JWC, suggesting that selection(s) of α-gliadin genes was not linked to CD epitopes in Japanese cultivars.