Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 21, 2006
Publication Date: August 7, 2006
Citation: Dupont, F.M., Lopez, R., Chan, R. 2007. Molar fractions of high molecular weight glutenins subunits are stable when wheat is grown under various mineral nutrition and temperature regimens. Journal of Cereal Science. 45:134-139. Interpretive Summary: Millions of tons of wheat flour are used every year by the baking and food industries. Variability in wheat flour quality is a common and serious problem for millers and bakers, and much of this variability has been attributed to environmental conditions during grain fill. The high molecular weight glutenins are wheat flour proteins are essential components of the glutenin polymer that gives flour its unique qualities of extensibility and elasticity. It was determined that the proportions of the five different high molecular weight glutenin subunits remain constant under different environmental conditions, thus contributing to stability of quality. The experiments are part of a broader research effort to understand the molecular basis for the effects of environment on flour quality.
Technical Abstract: Molar ratios of the high molecular weight glutenin subunits (HMW-GS) were determined for flour from bread wheat (Triticum aestivum L. cv Butte86) produced under 13 different combinations of temperature, water and mineral nutrition. Despite great differences in duration of grain fill, total protein per grain, flour protein percentage, and amount of HMW-GS per grain, a constant molar ratio was maintained for the five subunits Ax2* : Bx7 : By9 : Dx5 : Dy10 of 0.14 : 0.30 : 0.12 : 0.22 : 0.23. Similar molar ratios were found for five other U.S. wheat varieties with the same or differing subunit compositions. The Bx7 subunit accumulated to the highest level, although the varieties are not considered to be Bx7 over-expressers. The Dx and Dy subunits were present in smaller but nearly equal proportions and the Ax and By subunits were the least abundant. Although amount of HMW-GS per unit of flour is strongly affected by environment, the different subunits respond so similarly to environment that their final proportions appear to be determined mainly by genetic factors.