Protein composition and techno-functional properties of transgenic wheat with reduced α-gliadin content obtained by RNA interference

Abstract

An RNA interference approach was applied to silence α-gliadin genes in hexaploid wheat. A 313 bp fragment from the 5’ coding region of an α-gliadin sequence was cloned into the “hairpin” (hpRNAi) constructs pGliaRNAiSpacer and transformed into winter wheat cv. Florida by biolistic transformation. The resulting transgenic lines were then analysed for their α-gliadin content by an extraction/RPHPLC method. Distinct differences of the α-gliadin content ranging from unaltered to strongly reduced were found. Kernels of two lines with strongly reduced α-gliadin content were mixed, milled to white fl our, analysed for quantitative protein composition and used for functional testing in comparison with the wild type fl our. Protein analysis revealed that the lack of α-gliadins was compensated by an increase of albumins/globulins, ω-gliadins, γ-gliadins and HMW glutenin subunits. Dough resistance and extensibility of wild type and transgenic lines were similar, whereas gluten resistance of the transgenic increased drastically and extensibility decreased slightly. 2D gel electrophoresis showed that the transgenic wheat #6/6 lacked at least 20 storage proteins, but other distinct proteins were more abundant compared with the wild type. Major reductions in the α-gliadins do not make discernable differences in micro-scale measurements of flour functionality and have only a slightly detrimental effect in micro-baking tests.