Transformation of the US bread wheat Butte 86 and silencing of omega-5 gliadin genes

Authors: Altenbach, Susan; Allen, Paul

Submitted to: GM Crops
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2011
Publication Date: 4/19/2011
Citation: Altenbach, S.B., Allen, P.V. 2011. Transformation of the US bread wheat Butte 86 and silencing of omega-5 gliadin genes. GM Crops. 2(1):67-74.

Interpretive Summary: Wheat is among the top eight foods responsible for IgE-mediated food allergies. Biotechnology can be used to eliminate specific proteins that cause food allergies from plants. Such approaches require information about the genes that encode specific allergens so that DNA constructs can be designed that will inhibit their expression as well as methods to introduce the DNA construct into plants. Wheat-dependent exercise-induced anaphylaxis (WDEAI) is one type of allergy that occurs in sensitive individuals when the ingestion of wheat is followed by intense exercise. Certain gluten proteins, referred to as omega-5 gliadins, have been implicated as major allergens in WDEIA. A DNA construct was designed based on sequences of the omega-5 gliadins from the US wheat cultivar Butte 86 and genetic transformation methods were developed to introduce the construct into Butte 86 plants. Transgenic plants were created in which the omega-5 gliadins were either absent or substantially reduced relative to non-transformed controls. Flour from transgenic plants should be of value to individuals that suffer from WDEIA. Because many other genes and proteins expressed in Butte 86 grain have been characterized, the transformation methods also will be of value for many future studies on wheat flour quality and allergenic potential.

Technical Abstract: Complex groups of proteins determine the unique functional properties of wheat flour and are sometimes responsible for food intolerances and allergies in individuals that consume wheat products. Transgenic approaches can be used to explore the functions of different flour proteins, but are limited to the few wheat cultivars that can be transformed and also by the lack of detailed information about genes and proteins expressed in grain from those cultivars. The US bread wheat Butte 86 has been extensively characterized and a comprehensive proteome map was developed in which flour proteins were distinguished by mass spectrometry and associated with specific gene sequences. Here, this information has been used to design an RNA interference construct to silence the expression of genes encoding omega gliadins that trigger the food allergy wheat-dependent exercise-induced anaphylaxis (WDEIA). The construct was introduced into immature embryos from Butte 86 using biolistics and bialaphos-resistant plants were regenerated. Stable transformation and inheritance of the transgene were confirmed by PCR. Analysis of proteins in grain from transgenic plants demonstrated that the omega-5 gliadins were either absent or substantially reduced relative to non-transformed controls. Flour from transgenic plants should be of value to individuals that suffer from WDEIA. Additionally, more detailed analyses will provide insight into the roles of omega-5 gliadins in flour quality. The ability to genetically transform Butte 86 makes it possible to alter flour composition in a targeted manner in a commercial US wheat cultivar and should accelerate future research on flour quality and immunogenic potential.