Development of Assay Systems for Bioengineering Proteins that Affect Dough Quality and Wheat Utilization

The quality and utilization of wheat is largely dependent upon the exact physical/chemical properties of the doughs made from flour/water mixtures. Among the wheat seed components most correlated with dough visoelastic parameters are the high-molecular-weight (HMW) glutenin subunits whose disulfide cross-linked macropolymer is critical for dough functionality. We have used the tools of molecular biology, wheat transformation, heterologous expression of HMW-glutenin subunits in bacteria, and dough micro-mixing experiments to examine some of the molecular basis of HMW-glutenin functionality. In addition, we have developed sets of modified and synthetic gene constructs and transgenic wheat lines that will allow further examination of the role of the HMW-glutenins. Among the results from this work is evidence that the HMW-glutenin repeat domain is directly related to dough properties, the demonstration that interaction between subunits is dependent upon domain presence but not order, a novel understanding of the restrictions on intra-vs inter-chain disulfide bonds, the demonstration that HMW-glutenin genes can be transformed into wheat for simultaneously high expression of the transgene and suppression of the endogenous genes, and the construction of a set of modified HMW-glutenins capable of being epitope tagged for studying polypeptide subcellular processing and the fate of HMW-glutenins in dough mixing experiments.