The Composition and Quantity of Wheat Glutenin Subunits in Relation to High Molecular Weight Glutenin Polymers and their Effects on Breadmaking Quality

Two biotypes of Australian wheat cultivars,differing only in the composition of high molecular weight (HMW) glutenin subunits,and three America hard red spring (HRS) wheat cultivars with the same HMW glutenin subunits but different breadmaking quality were used in this study.The compositions of HMW and low molecular weight (LMW) glutenin subunits for the different glutenin aggregates and SDS-insoluble glutenin polymers were analyzed by SDS-PAGE. It was found that the biotype with HMW glutenin subunits 5 + 10 and better breadmaking quality had a greater size distribution of glutenin polymers than the type with subunits 2 + 12. The proportion of HMW glutenin subunits and LMW glutenin subjunis played an important role in determining the size distributions of glutenin aggregates. Glutenin polymers of greater size were associated with a higher proportion of HMW glutenin subunits and LMW glutenin subunits. SDS-insoluble glutenin polymers which have a greater proportion of HMW glutenin subunits and LMW glutenin subunits,were larger in size than those SDS soluble polymers. The difference in the size distribution of glutenin polymers contributed to the difference in breadmaking quality among different HRS wheat cultivars. Therefore,the size distribution of glutenin polymers was one of significant factors in determining breadmaking quality of different cultivars.