Identification of a New Class of Recombinant Prolamin Genes in Wheat

A novel storage protein gene with obvious [corrected] chimeric structure was isolated from an immature kernel-specific cDNA library prepared from the old Hungarian wheat [corrected] variety, Bánkúti 1201. This clone contains gamma-gliadin sequences in the 5' region and LMW-glutenin sequences on the 3' end. A frameshift mutation was also introduced by the putative recombination event. Hence, the amino acid sequence of the C-terminal region was transformed to a completely new polypeptide. Based on this finding, 7 additional recombinant prolamin genes of similar structure were isolated with specific PCR primers. The 8 chimeric clones seem to be derived from 4 individual gamma-gliadin and 3 LMW-glutenin sequences. These genes show remarkable diversity in size, gliadin:glutenin ratio, frameshift mutations, and sulphur content. The putative functional characteristics of the chimeric polypeptides and problems related to the origin of the encoding genes are discussed.