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

Fernando Pistón,Marta Rodríguez-Quijano,Francisco Barro,Javier Gil-Humanes,Karol Sestak

doi:10.1371/journal.pone.0024754

Fernando Pistón, Marta Rodríguez-Quijano + Show 3 more

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https://doi.org/10.1371/journal.pone.0024754

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Abstract

BackgroundGliadins are a major component of gluten proteins but their role in the mixing of dough is not well understood because their contribution to wheat flour functional properties are not as clear as for the glutenin fraction.Methodology/Principal FindingsTransgenic lines of bread wheat with γ-gliadins suppressed by RNAi are reported. The effects on the gluten protein composition and on technological properties of flour were analyzed by RP-HPLC, by sodium dodecyl sulfate sedimentation (SDSS) test and by Mixograph analysis. The silencing of γ-gliadins by RNAi in wheat lines results in an increase in content of all other gluten proteins. Despite the gluten proteins compensation, in silico analysis of amino acid content showed no difference in the γ-gliadins silenced lines. The SDSS test and Mixograph parameters were slightly affected by the suppression of γ-gliadins.Conclusions/SignificanceTherefore, it is concluded that γ-gliadins do not have an essential functional contribution to the bread-making quality of wheat dough, and their role can be replaced by other gluten proteins.

Highlights

Wheat grain is the most important source of proteins for human beings, with 80% of the total wheat protein being represented by the gluten proteins [1]
Chromatograms from transgenic lines showed a strong decrease of the peaks in the c-gliadins region in comparison with that of the wild types, whereas the v and a regions increased the areas of their peaks in the transgenic lines of both genotypes (Figures 1A and 1B)
A small peak appeared in some Reversed-phase high-performance liquid chromatography (RP-HPLC) runs in transgenic and wild-type lines of genotypes BW208 and BW2003 at around 27.7 min retention time, which could be related to high molecular weight (HMW)-GS aggregate of two protein or a HMW-GS protein degradation product

Summary

Introduction

Wheat grain is the most important source of proteins for human beings, with 80% of the total wheat protein being represented by the gluten proteins [1]. Wheat gluten consists of over 50 different proteins, which largely determine the dough mixing properties of flours and their suitability for bread-making. These proteins are traditionally classified into the glutenins and the gliadins [2]. Gliadins account for about 50% of the gluten proteins, their role in the mixing properties of dough is not well understood This is because correlations between gliadin composition and the functional properties of dough are not as clear as for the HMW-GS. Gliadins are a major component of gluten proteins but their role in the mixing of dough is not well understood because their contribution to wheat flour functional properties are not as clear as for the glutenin fraction

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Conclusion