Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2010
Publication Date: 1/3/2011
Citation: Graybosch, R.A., Seabourn, B.W., Chen, Y.R., Blechl, A.E. 2010. Quality and agronomic effects of three high-molecular-weight glutenin subunit transgenic events in winter wheat. Cereal Chemistry. 88(1):95-102.
Interpretive Summary: The unique viscoelastic properties of wheat are due to the presence of gluten proteins in flour. One particular group of gluten proteins, the glutenin subunits, provides the strength and elasticity that is unique to wheat, and that is essential for the production of leavened bakery products. This study was undertaken to determine whether over-production of some specific glutenins, namely, high-molecular-weight subunits, would result in improved bread-making properties. Genetic engineering techniques were used to increase the copy number of genes encoding specific glutenin subunits. These “transgenic events” resulted in an increase in the amount of specific glutenin subunits in the grain and flour. There was no effect on grain yield or other physical grain properties except that one particular transgenic event increased grain hardness, or resistance to milling. All events resulted in marked increases in dough strength, but in general, the doughs produced were too strong for commercial applications. The study did demonstrate a range of response, and suggested that fine-tuning the amount of glutenin via genetic modification could result in doughs useful in modern bakery operations.
Technical Abstract: Quality and agronomic effects of three transgenic high-molecular-weight glutenin subunit (HMWGS) events were characterized in advanced-generation breeding lines of hard winter wheat (Triticum aestivum L.) in three Nebraska (U.S.A.) crop years. Two of the transgenic events studied, Dy10-E and B52a-6, over-express HMWGS 1Dy10, while the third event, Dx5+Dy10-H over-expresses HMWGS 1Dx5 and, to a much lesser extent, 1Dy10. In addition, novel proteins, possessing solubility characteristics defining them as HMWGS, were present in Dx5+Dy10-H and B52a-6. Average grain yield of lines derived from the three transgenic events was statistically lower than that of a group of control cultivars and advanced breeding lines, but not lower than the mean of their respective non-transgenic sibs. Grain hardness was influenced by one of the events. Dx5+Dy10-H produced harder kernels than controls, its non-transgenic sister lines, and the two additional transgenic events. All three events produced doughs with unusual mixing properties, likely not directly useful in commercial applications. As a consequence, loaf volumes were depressed, but to variable degrees by the three events. The results indicated that over-expression of HMWGS could eventually lead to improved breadmaking quality by optimizing the level of over-expression, or by development and characterization of additional events.