Development of genetically modified wheat to assess its dough functional properties.

Abstract

End-use functionality of bread wheat depends mainly on the protein content, the presence of particular subunits of high and low molecular weight glutenin, the ratio of high molecular weight to low molecular weight glutenin subunits, and the ratio of glutenin to gliadin. The exact contribution of each of these factors to end-use functionality is still largely unknown. Transgenic plants can allow these factors to be studied within a particular background thus contributing to our understanding of end-use functionality. Two Canadian wheat lines, one of them containing high molecular weight glutenin subunits (HMW-GS) coded by all three Glu-1 loci and one line null at all three loci were assessed for dough rheological properties and bread and tortilla-making properties. Protein composition of the flours were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis, size exclusion high performance liquid chromatography, and sedimentation test. Proteins in the samples were fractionated and the proportions of monomeric proteins, soluble glutenin, and insoluble glutenin were quantified. Functionality of the flours were characterized by small-scale methods such as the 2 g mixograph, 10 g farinograph, and micro-extension testing. End-use quality was evaluated by small-scale bread and tortilla production. Mixograph development time and mixograph peak height were much higher for the lines containing HMW-GS. The lines null for HMW-GS showed no resistance to extension. Lines null for HMW-GS produced 'brick'-like bread. Tortilla prepared from the null lines had poor rollability and lower puncture force. The results showed very strong dependencies of quality on the presence of HMW-GS.