Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 16, 2013
Publication Date: February 24, 2014
Citation: Altenbach, S.B., Tanaka, C.K., Allen, P.V. 2014. Quantitative proteomic analysis of wheat grain proteins reveals differential effects of silencing of omega-5 gliadin genes in transgenic lines. Journal of Cereal Science. 59:118-125. Interpretive Summary: Quantitative two-dimensional gel electrophoresis was used to analyze the protein compositions of four transgenic wheat lines in which genes encoding a small group of allergenic proteins were silenced. All of the lines showed substantial reductions in the levels of the targeted allergenic proteins. In two of the lines, the allergenic proteins were not detected at all. Each line was unique in terms of other changes that were observed in protein composition. Some of the lines showed small reductions in other closely-related gluten proteins that may be due in part to similarities among the sequences of the different proteins, while some lines exhibited small increases in proteins in other gluten and non-gluten protein classes. The study made it possible to select transgenic lines that will provide insight into how decreases in a specific class of allergenic proteins can affect the quality and allergenic potential of wheat flour.
Technical Abstract: Novel wheat lines with altered flour compositions can be used to decipher the roles of specific gluten proteins in flour quality. Grain proteins from transgenic wheat lines in which genes encoding the omega-5 gliadins were silenced by RNA interference (RNAi) were analyzed in detail by quantitative 2-dimensional gel electrophoresis (2-DE). The precise effects of the genetic modifications on the proteome were assessed in four homozygous lines generated with the same RNAi construct. Two of the lines showed >80% decreases in omega-5 gliadins. One had relatively minor changes in the levels of other gluten proteins, while the other showed a small decrease in an omega-1,2 gliadin and increases in a few high-molecular-weight glutenin subunits (HMW-GS) and alpha gliadins. In the other two lines, omega-5 gliadins were not detectable by 2-DE. However, there were notable reductions in all of the omega-1,2 gliadins. Small decreases in an s-type low-molecular-weight glutenin subunit (LMW-GS) and a gamma gliadin and small increases in a HMW-GS and alpha gliadin were also detected in one of the lines. The other line showed notable decreases in three HMW-GS and an s-type LMW-GS as well as increases in two m-type LMW-GS and several alpha gliadins. This line also showed increases in both serpins and triticin. The study demonstrates that the same RNAi construct can have differential effects on the wheat grain proteome in different transgenic events and highlights the importance of detailed proteomic analyses of transgenic grain prior to selecting lines for further assessment of flour quality and allergenic potential.