Association between high molecular weight subunits of glutenin and bread-making quality in wheat lines derived from backcrosses between Triticum aestivum and Triticum speltoides

Abstract

Further evidence that the high molecular weight subunits of glutenin are involved in determining the bread-making quality of wheat cultivars was obtained by Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE) of reduced glutenin subunits from 10 wheat lines possessing leaf rust resistance derived from Triticum speltoides . Two of these lines, obtained by backcrossing four or five times to the variety Neepawa as the recurrent parent, showed very poor baking quality. The most obvious difference in protein composition between these two lines and Neepawa itself was the absence in the two lines of two high molecular weight subunits, 3 and 10, coded for by a gene locus on the long arm of chromosome ID ( Glu-Dld ); the poor bread-making quality of these two lines appeared to be attributable to the absence of these two subunits. In another line, which had somewhat lower baking quality than either Neepawa or Manitou, the most obvious difference in protein composition was the replacement of two high mol. wt glutenin subunits, 5 and 9, which are coded for by a gene locus on the long arm of chromosome 1B ( Glu-Blc ), by two subunits, termed S1 and S2, that have not been described previously. Introduction of these subunits, which are presumed to be derived from T. speltoides , apparently was responsible for the poorer baking quality of this line, and this was consistent with previous conclusions that subunits 5 and 9 are associated with good baking quality.