Location: Corn Insects and Crop Genetics ResearchTitle: Recurrent selection for transgene expression levels in maize results in proxy selection for a native gene with the same promoter Author
|Bodnar, Anastasia - Iowa State University|
|Shroder, Megan - Iowa State University|
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2016
Publication Date: 2/19/2016
Citation: Bodnar, A.L., Shroder, M.N., Scott, M.P. 2016. Recurrent selection for transgene expression levels in maize results in proxy selection for a native gene with the same promoter. PLoS One. 11(2):e0148587. doi: 10.1371/journal.pone.0148587.
Interpretive Summary: Transgenes can be used to produce valuable proteins in plants. Often, the level of the protein encoded by the transgene has an impact on the performance or value of the transgenic plant. Our ability to design transgenes to produce a desired level of protein is very limited. In this study, we demonstrate that it is possible to use traditional breeding methods based on recurrent selection to control the level of a transgene-encoded protein. We also demonstrate that it is possible to control a native gene by selection for levels of a transgene with regulatory sequences in common with the native gene. This work demonstrates a new method for controlling expression of genes, providing scientists with another tool with which to investigate gene expression and help understand how genes function to produce valuable traits.
Technical Abstract: High expression levels of a transgene can be very useful, making a transgene easier to evaluate for safety and efficacy. High expression levels can also increase the economic benefit of the production of high value proteins in transgenic plants. The goal of this research is to determine if recurrent selection for expression of a transgene will result in higher expression, and if selection for expression of a transgene controlled by a native promoter will also increase expression of the native gene with the same promoter. To accomplish this goal we used transgenic maize containing a construct encoding green fluorescent protein controlled by the maize endosperm-specific 27kDa gamma zein seed storage protein promoter. Recurrent selection for fluorescence intensity was carried out in two genetic backgrounds. After three generations of selection, both selected populations were significantly more fluorescent and had significantly higher levels of 27kDa gamma zein than the randomly selected control populations. These higher levels of the 27kDa gamma zein occurred independently of the presence of the transgene. The results show that recurrent selection can be used to increase expression of a transgene and that selection for a transgene controlled by a native promoter can increase expression of the native gene with the same promoter via proxy selection. Moreover, these proxy selection effects are maintained in the absence of the transgene, demonstrating that proxy selection can be used to produce non-transgenic plants with desired changes in gene expression.