Prolamin aggregation, gluten viscoelasticity, and mixing properties of transgenic wheat lines expressing 1ax and 1dx high molecular weight glutenin subunit transgenes

The composition of high molecular weight (HMW) subunits of glutenin determines the gluten strength and influences the baking quality of bread wheat. Here, the effect of transgenes coding for subunits 1Ax1 and 1Dx5 was studied in two near-isogenic wheat lines differing in their HMW subunit compositions and mixing properties. The subunits encoded by the transgenes were overexpressed in the transformed lines and accounted for 50-70% of HMW subunits. Overexpression of 1Ax1 and 1Dx5 subunits modified glutenin aggregation, but glutenin properties were much more affected by expression of the 1Dx5 transgene. This resulted in increased cross-linking of glutenin polymers. In dynamic assay, the storage and loss moduli of hydrated glutens containing 1Dx5 transgene subunits were considerably enhanced, whereas expression of the 1Ax1 transgene had a limited effect. The very high strength of 1Dx5 transformed glutens resulted in abnormal mixing properties of dough. These results are discussed with regard to glutenin subunit and glutenin polymer structures.