Abstract
Avenin-like b proteins are a small family of wheat storage proteins, each containing 18 or 19 cysteine residues. The role of these proteins, with high numbers of cysteine residues, in determining the functional properties of wheat flour is unclear. In the present study, two transgenic lines of the bread wheat overexpressing avenin-like b gene were generated to investigate the effects of Avenin-like b proteins on dough mixing properties. Sodium dodecyl sulfate sedimentation (SDSS) test and Mixograph analysis of these lines demonstrated that overexpression of Avenin-like b proteins in both transgenic wheat lines significantly increased SDSS volume and improved dough elasticity, mixing tolerance and resistance to extension. These changes were associated with the increased proportion of polymeric proteins due to the incorporation of overexpressed Avenin-like b proteins into the glutenin polymers. The results of this study were critical to confirm the hypothesis that Avenin-like b proteins could be integrated into glutenin polymers by inter-chain disulphide bonds, which could help understand the mechanism behind strengthening wheat dough strength.
Highlights
Wheat is currently an important human food resource that can be processed into a range of foods such as breads, cakes, biscuits, pastas and noodles
We have clearly demonstrated that all transgenic lines that tested PCR positive (PCR analysis) for the presence of CaMV35S terminator were positive for transgene expression, determined using the anti-avenin-like b proteins polyclonal antibody
Because protein compositions played a critical role in dough functionality, we first determined the differences in protein compositions between transgenic and control wheat lines
Summary
Wheat is currently an important human food resource that can be processed into a range of foods such as breads, cakes, biscuits, pastas and noodles. On the other hand, have a wide range of molecular weights and contain high-molecular weight glutenin subunits (HMW-GS) and lowmolecular weight glutenin subunits (LMW-GS) These glutenins can form the high molecular mass glutenin polymers and largely contribute to wheat dough strength [5]. The widely-held view of gluten structure was summarized by Shewry et al [7] who suggested a structural model for wheat gluten, in which the HMW subunits crosslink with each other in a head-to-tail fashion by inter-chain disulphide bonds and form an ‘elastic backbone’, while LMW subunits crosslink to this backbone basis and form ‘branches’. Gliadins may interact with the glutenin polymers by strong covalent and non-covalent forces and contribute to gluten viscosity [2] In this model, the HMW-GS plays a determinant role in dough strength. Several studies used transgenic wheat lines to demonstrate that LMW glutenin subunits were important determinants of quality in processed wheat [18,19,20,21]
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