Three coding sequences of gliadins genes, designed as Gli2_Du1, Gli2_Du2 and Gli2_Du3, were isolated from thegenomic DNA of Triticum durum accessions CItr5083. Gli2_Du1 and Gli2_Du2 contain 945 and 864 bp, encoding themature proteins with 314 and 287 amino acid residues, respectively. Gli2_Du3 is recognized as a pseudogene due to thestop codon occurring in the coding region. The pseudogenes, commonly occurring in gliadins family, are attributed to thesingle base change C → T. The amino acid sequences deduced from these gene sequences were characterized with thetypical structure of α-gliadin proteins, including the toxic sequences (PSQQQP). The peptide fraction PF(Y)PP(Q) isthought to be an extra unit of repetitive domain, slightly diverging from the previous report. Six cysteine residues wereobserved within two unique domains. Phylogenetic analysis showed Gli2_Du2 and Gli2_Du3 were closely related to thegenes on chromosome 6A, whereas Gli2_Du1 seems to be more homologous with the genes on chromosome 6B.
A novel HMW glutenin subunit gene 1Dy10.1 was isolated and characterized from Xinjiang wheat (Triticum petropavlovskyi. Udacz. et Migusch) accession Daomai 2. The complete open reading frame (ORF) of 1Dy10.1 was 1 965 bp, encoding 655 amino acids. The numbers and distribution of cysteines in 1Dy10.1 were similar to those of 1Dy10 and other y-type subunits. In the N-terminal of 1Dy10.1, an amino acid was changed from L (leucine) to P (proline) at position 55. The repetitive domain of 1Dy10.1 differed from those of known HMW subunits by substitutions, insertions or/and deletions involving single or more amino acid residues. In the repetitive domain of subunit 1Dy10.1, the deletion of tripeptide GQQ in the consensus unit PGQGQQ resulted in the appearance of the motif PGQ that have not been observed in other known y-type HMW subunits. In comparison with the subunit 1Dy12, a deletion of dipeptide GQ, which occurred in subunit 1Dy10, was also observed in subunit 1Dy10.1. The cloned 1Dy10.1 gene had been successfully expressed in Escherichia coli, and the expressed protein had the identical mobility with the endogenous subunit 1Dy10.1 from seed.
