PRODUCTION OF WHEAT GERMPLASM WITH ENHANCED BAKING QUALITY
Location: Crop Improvement & Utilization Research
Title: Expression Patterns in Transgenic Wheats with Elevated Levels of Dx5 and/or Dy10 Glutenin Subunits
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: April 1, 2007
Publication Date: June 1, 2007
Citation: Blechl, A.E., Lin, J.W., Nguyen, S., Dupont, F.M., Vensel, W.H., Chan, R., Anderson, O.D., Bregitzer, P.P., Fiedler, D.J. 2007. Expression Patterns in Transgenic Wheats with Elevated Levels of Dx5 and/or Dy10 Glutenin Subunits. In: George L. Lookhart, Perry K.W. Ng, editors. Gluten Proteins 2006. Minneapolis, MN: AACCI. p. 107-111.
In order to study the effects of independently increasing the levels of high-molecular-weight glutenin subunits Dx5 and Dy10, we added copies of their genes to wheat by genetic transformation. Among 30 lines produced, six exhibited transgene-mediated co-suppression and eight showed the presence of extra bands of unpredicted sizes in SDS-PAGE. Several of the extra bands were isolated from gels and characterized by mass spectrometry. All but one were variants of glutenin subunit Dx5, evidently altered in size during the transformation process by an unknown mechanism. Thirteen lines with increases in Dx5 and/or Dy10 were further characterized. Increases in subunits Dx5 or Dy10 ranged from 2.3 to 3.5-fold or 2.8 to 5.4-fold, respectively, their levels in the non-transformed parent. The amount of polymeric protein increased more with increases in Dx5 than with increases in Dy10. In the 2-gram mixograph, doughs from the transgenic lines had longer mix times and improved tolerance compared to those from the non-transformed parent. However, doughs with more than 2.6-times the parental Dx5 levels could not be mixed in this instrument, while doughs with 5.4 the parental Dy10 levels were mixable if sufficient time was allowed. Agronomic characteristics of these lines were assessed in two years of field trials. Most were indistinguishable from their non-transformed parent, but two exhibited reductions in yield and height. These experiments show that mixing properties can be changed by adding genes to increase the levels of Dx5 and/or Dy10 and that such changes can be made without altering yield. Dx5 and Dy10 contributed to functionality in qualitatively and quantitatively different ways and their effects on mixing were at least partially additive. Some transformation events showed unintended properties including low yield, reductions in synthesis of native HMW-GS, and altered transgene-encoded protein products. The latter results underscore the importance of extensive characterization of transgenic wheat lines.