Molecular Cloning and Comparative Analysis of Novel SRL-/TRQ-type ω-Gliadin Genes from Tall Wheatgrass.

Wild tall wheatgrass ( Agropyron elongatum) is an important relative of wheat. Seven distinct sequences, each consisting of a single intron-less intact open reading frame, were amplified from the genomic DNA of tall wheatgrass, using degenerate primers special to SRL-/TRQ-type ω-gliadin genes targeted at Gli-1 loci. The amplified sequences shared a high degree of homology to known ω-gliadin sequences. Their lengths ranged from 837 to 951 bp, and those of the corresponding deduced peptides, from 278 to 316 residues. Each deduced polypeptide possessed a typical structure of ω-gliadin consisting of a signal peptide with 19 amino acid residues, a short N-terminal and C-terminal conserved domain, and a long variable repetitive domain. Three of the seven sequences matched the SRL-type ω-gliadin, while the other four matched the TRQ-type. Reverse transcriptase polymerase chain reaction results showed five of the seven ω-gliadin genes expressed in the endosperm of tall wheatgrass seed. In addition, the seven tall wheatgrass genes clustered closely with one another, except clone JN092577, which was more closely related to three B-genome SRL-type ω-gliadin genes. Variation and evolutionary relationship of the ω-gliadin family genes were also illustrated and discussed. [ABSTRACT FROM AUTHOR]