The Introgression of RNAi Silencing of γ-Gliadins into Commercial Lines of Bread Wheat Changes the Mixing and Technological Properties of the Dough

In the present work the effects on dough quality by the down-regulation of γ-gliadins in different genetic backgrounds of bread wheat were investigated. RNAi-mediated silencing of γ-gliadins was introgressed by conventional crossing into three commercial bread wheat lines (namely ‘Gazul’, ‘Podenco’ and ‘Arpain’), and along with the transgenic line A1152 (cv. Bobwhite) compared with their respective wild types. The protein fractions were quantified by RP-HPLC, whereas the technological and mixing properties were assessed by SDSS test and by the Mixograph instrument. Principal component analysis (PCA) was carried out for both the wild types and the transgenic lines, showing differences in the factors affecting the technological and mixing properties of the dough as a consequence of the reduction of the γ-gliadins. In transgenic lines, the α- and ω-gliadins, and total gliadins negatively affected the dough strength and tolerance to over-mixing, whereas the L/H ratio showed the opposite effect, positively influencing the dough quality. The increase of the SDSS volume in the transgenic lines of ‘Gazul’, ‘Podenco’ and ‘Arpain’ indicates increased gluten strength and quality respect to the wild types. SDSS volume was found to be positively influenced by the amount of glutenins, which were also increased in the transgenic lines. In addition, a positive effect was observed in the MT, PR1 and RBD in some of the transgenic lines of ‘Podenco’ and ‘Arpain’. In conclusion, the down-regulation of γ-gliadins resulted in stronger doughs and a better tolerance to over-mixing in some transgenic lines. Although the reduction of γ-gliadins seems not to have a direct effect on the mixing and bread-making properties, the compensatory effect on the synthesis of the other prolamins may result in stronger doughs with improved over-mixing resistance.

[1]  P. I. Payne.  Genetics of Wheat Storage Proteins and the Effect of Allelic Variation on Bread-Making Quality , 1987 .

[2]  P. Shewry,et al.  Mixing properties and dough functionality of transgenic lines of a commercial wheat cultivar expressing the 1Ax1, 1Dx5 and 1Dy10 HMW glutenin subunit genes , 2009 .

[3]  C. Rosell,et al.  Significant down-regulation of γ-gliadins has minor effect on gluten and starch properties of bread wheat , 2012 .

[4]  R. Hamer,et al.  Structure and functional properties of gluten. , 2009 .

[5]  H. Wieser,et al.  Quantitative Determination of Gluten Protein Types in Wheat Flour by Reversed‐Phase High‐Performance Liquid Chromatography , 1998 .

[6]  O. Anderson,et al.  Isolation and characterization of wheat ω-gliadin genes , 2001, Theoretical and Applied Genetics.

[7]  P. Shewry,et al.  Silencing of γ-gliadins by RNA interference (RNAi) in bread wheat , 2008 .

[8]  B. S. Khatkar,et al.  Functional properties of wheat gliadins. I. Effects on mixing characteristics and bread making quality , 2002 .

[9]  A. Worland,et al.  Allelic variation of glutenin subunits and gliadins and its effect on breadmaking quality in wheat: Analysis of F5 progeny from Chinese Spring × Chinese Spring (Hope 1A) , 1987 .

[10]  H. Belitz,et al.  The course of the SDS and Zeleny sedimentation tests for gluten quality and related phenomena studied using the light microscope , 1993 .

[11]  Ross Ihaka,et al.  Gentleman R: R: A language for data analysis and graphics , 1996 .

[12]  F. Stoddard,et al.  Effects of Incorporated Glutenins on Functional Properties of Wheat Dough , 2000 .

[13]  A. Tatham,et al.  Effects of Gliadin Fractions on Functional Properties of Wheat Dough Depending on Molecular Size and Hydrophobicity , 2001 .

[14]  J. Blackman,et al.  Correlations between the inheritance of certain high‐molecular weight subunits of glutenin and bread‐making quality in progenies of six crosses of bread wheat , 1981 .

[15]  P. Shewry,et al.  Technological quality of field grown transgenic lines of commercial wheat cultivars expressing the 1Ax1 HMW glutenin subunit gene , 2008 .

[16]  O. Anderson,et al.  The wheat γ-gliadin genes: characterization of ten new sequences and further understanding of γ-gliadin gene family structure , 2001, Theoretical and Applied Genetics.

[17]  P. Shewry,et al.  high molecular weight subunits of wheat, barley and rye: genetics, molecular biology, chemistry and role in wheat gluten structure and functionality , 1989 .

[18]  P. Shewry,et al.  Genetics of wheat gluten proteins. , 2003, Advances in genetics.

[19]  Peter R. Shewry,et al.  Wheat: chemistry and technology. , 2009 .

[20]  G. Tamminga,et al.  The effects of wheat flour proteins on mixing and baking―Correlations with protein fractions and high molecular weight glutenin subunit composition by gel electrophoresis , 1989 .

[21]  J. Skerritt,et al.  Isolation and Functionality Testing of Low Molecular Weight Glutenin Subunits , 1998 .

[22]  F. Barro,et al.  Down-Regulating γ-Gliadins in Bread Wheat Leads to Non-Specific Increases in Other Gluten Proteins and Has No Major Effect on Dough Gluten Strength , 2011, PloS one.

[23]  F. El-Haramein,et al.  Crop quality evaluation methods and guidelines. , 1986 .

[24]  A. Tatham,et al.  Effects of α-, β-, γ- and ω-Gliadins on the Dough Mixing Properties of Wheat Flour , 1997 .

[25]  Y. Zhu,et al.  Generation of transgenic wheat lines with altered expression levels of 1Dx5 high-molecular weight glutenin subunit by RNA interference , 2008 .

[26]  K. F. Finney,et al.  Functional (breadmaking) and biochemical properties of wheat flour components. VIII. Starch , 1971 .

[27]  F. Macritchie.  Physicochemical Properties of Wheat Proteins in Relation to Functionality , 1992 .

[28]  P. Shewry,et al.  N-terminal amino acid sequences of ω-gliadins and ω-secalins: Implications for the evolution of prolamin genes , 1983 .

[29]  J. Pátek,et al.  Polyacrylamide gel electrophoresis for wheat variety identification: Effect of variables on gel properties , 1985 .

[30]  P. Ng,et al.  Characterization of wheat with strongly reduced α-gliadin content. , 2007 .

[31]  D. Lafiandra,et al.  Production and characterization of a transgenic bread wheat line over-expressing a low-molecular-weight glutenin subunit gene , 2003, Molecular breeding.

[32]  P. Shewry,et al.  Modification of the Low Molecular Weight (LMW) Glutenin Composition of Transgenic Durum Wheat: Effects on Glutenin Polymer Size and Gluten Functionality , 2005, Molecular Breeding.

[33]  C. N. Law,et al.  Genetic linkage between endosperm storage protein genes on each of the short arms of chromosomes 1A and 1B in wheat , 2004, Theoretical and Applied Genetics.

[34]  P. Shewry,et al.  Separation of plant proteins by electrophoresis. , 1995, Methods in molecular biology.

[35]  H. Wieser,et al.  The location of disulphide bonds in α-type gliadins , 1995 .

[36]  P. Ng,et al.  Silencing the α-gliadins in hexaploid bread wheat. , 2007 .

[37]  J. Vereijken,et al.  Evaluating HMW glutenin subunits to improve bread-making quality of wheat , 1993 .

[38]  W. Kronstad,et al.  Reliability of Two Laboratory Techniques to Predict Bread Wheat Protein Quality in Nontraditional Growing Areas 1 , 1987 .

[39]  F. Macritchie,et al.  Allelic Variation at Glutenin Subunit and Gliadin Loci, Glu-1, Glu-3 and Gli-1 of Common Wheats. II. Biochemical Basis of the Allelic Effects on Dough Properties , 1994 .

[40]  V. Srivastava,et al.  Integration and expression of the high-molecular-weight glutenin subunit 1Ax1 gene into wheat , 1996, Nature Biotechnology.

[41]  P. Shewry,et al.  Transformation of wheat with high molecular weight subunit genes results in improved functional properties , 1997, Nature Biotechnology.

[42]  P. Shewry,et al.  Technological quality of transgenic wheat expressing an increased amount of a HMW glutenin subunit , 2005 .

[43]  J. Anderson,et al.  Optimizing the SDS sedimentation test for end-use quality selection in a soft white and club wheat breeding program , 1999 .

[44]  L. Sollid,et al.  Effective shutdown in the expression of celiac disease-related wheat gliadin T-cell epitopes by RNA interference , 2010, Proceedings of the National Academy of Sciences.

[45]  R. Hamer,et al.  Large-scale separation of gliadins and their bread-making quality , 1994 .

[46]  G. Branlard,et al.  Diversity of grain proteins and bread wheat quality , 1985 .