Isolation and characterization of wheat omega-gliadin genes

The DNA sequences of two full-length wheat omega -gliadin prolamin genes (o mega F20b and omega G3) containing significant 5' and 3' flanking DNA seque nces are reported. The omega F20b DNA sequence contains an open reading fra me encoding a 30,460-Dalton protein, whereas the omega G3 sequence would en code a putative 39,210-Dalton protein except for a stop codon at amino-acid residue position 165. These two omega -gliadin genes are closely related a nd are of the ARQ-/ARE-variant type as categorized by the derived N-termina l amino-acid sequences and aminoacid compositions. The omega -gliadins were believed be related to the omega -secalins of rye and the C-hordeins of ba rley, and analyses of these complete omega -gliadin sequences confirm this close relationship. Although the omega -type sequences from all three speci es are closely related, in this analysis the rye and barley co-type sequenc es are the most similar in a pairwise comparison. A comparison of omega -gl iadin flanking sequences with respect to that of their orthologs and with r espect to wheat gliadin genes suggests the conservation of flanking DNA nec essary for gene function. Sequence data for members of all major wheat prol amin families are now available.