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

To better understand molecular evolution of the large alpha-gliadin gene family and provide a potential value for wheat quality improvement, total 32 alpha-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 alpha-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 alpha-gliadin gene sequences, and we found that the distribution of the epitopes varied between Dasypyrum genomes. Phylogenetic analysis of the Dasypyrum alpha-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 alpha-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 alpha-gliadin promoter region, we produced sequence-characterized amplified region ( SCAR) markers, and localized the Dasypyrum alpha-gliadin genes on chromosome 6 VS. The SCAR markers can be used to target the introgression of Dasypyrum