Identification of α-gliadin genes in Dasypyrum in relation to evolution and breeding

Abstract

To better understand molecular evolution of the large α-gliadin gene family and provide a potential value for wheat quality improvement, total 32 α-gliadin gene sequences were isolated from the two Dasypyrum species, D. villosum. (L.) Candargy and D. breviaristatum (Lindb. F.) Frederisksen. Twelve of 32 sequences contained the in-frame stop condons were predicted to be pseudogenes, suggesting the high variation of gliadin genes in Dasypyrum genome. There are five D. breviaristatum α-gliadin sequences present additional cysteine residues. Four peptides which have been identified as T cell stimulatory epitopes in celiac disease (CD) patients through binding to HLA-DQ2/8 were searched to all Dasypyrum α-gliadin gene sequences, and we found that the distribution of the epitopes varied between Dasypyrum genomes. Phylogenetic analysis of the Dasypyrum α-gliadin genes indicated that the sequences from D. breviaristatum displayed higher variation than those from D. villosum, and the genomic differentiation occurred between the two Dasypyrum species. Moreover, the promoter region of the Dasypyrum α-gliadin genes consisted of four different lengths, indicative of the retrotransposons involving the evolution of the gliadin gene promoters. Based on the specific sequences of the Dasypyrum α-gliadin promoter region, we produced sequence-characterized amplified region (SCAR) markers, and localized the Dasypyrum α-gliadin genes on chromosome 6 VS. The SCAR markers can be used to target the introgression of Dasypyrum α-gliadin genes in wheat–Dasypyrum derivatives.