Plant Genome III Conference

EXPRESSION OF A NOVEL HIGH MOLECULAR WEIGHT GLUTENIN SUBUNIT IN TRANSGENIC WHEAT.

Genetic studies have established correlations between the presence of certain High Molecular Weight (HMW) glutenin subunits of wheat and the elastic properties of bread dough [P. Payne, Ann. Rev. Plant Physiol. 38, 141 (1987)]. In order to investigate this relationship more closely and to determine whether the overall levels of these proteins are important for dough functionality, we sought to increase the amounts of the HMW glutenin subunits in wheat by introducing additional genes encoding them. In order to distinguish the new subunit from the endogenous ones, a hybrid glutenin gene was constructed by fusing the promoter and N- terminal coding region of the DylO HMW glutenin subunit gene to the repeat region and C-terminal coding regions of the Dx5 subunit gene. The protein encoded by this gene differs in mobility from the other HMW glutenin subunits of cultivar Bobwhite, the wheat targeted for transformation. Transgenic wheat lines were obtained by co-transformation of the hybrid gene with a plasmid encoding a selectable marker for Bialaphos resistance using our published procedure [T. Weeks et al., Plant Physiol., 102, 1077 (1993)]. Expression of the unselmted HMW glutenin subunit gene was readily detected among the transgenic progeny of more than half of these lines by Coomassie blue staining of SDS-PAGE protein gels of seed extracts. The lines have varying levels of expression of the introduced genes and thus will provide an isogenic lines of flours whose theological properties can be compared for correlations between HMW glutenin subunit levels and bread dough properties. This is the, first report of the use of a cereal gene promoter to drive expression of a cereal storage protein in a transgenic cereal.