ARS | Publication request: Maize transgenes containing zein promoters are regulated by opaque2

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 10, 2011
Publication Date: August 19, 2011
Citation: Schroder, M.N., Floyd, B.E., Scott, M.P. 2011. Maize transgenes containing zein promoters are regulated by opaque2. Crop Science. 51(6):2716-2720.

Interpretive Summary: Transgenes are an effective tool for crop improvement. Better understanding of how transgenes function will allow researchers to develop transgenic products with reduced risk of unintended effects. The objective of this study was to determine if two model transgenes that produce the fluorescent marker protein GFP in maize grain function according to predictions based on our understanding of how native maize genes function. We correctly predicted our transgenes would produce less fluorescence in the presence of the mutation opaque2. This observation suggests that basic information about gene expression can be applied to transgenes to predict their function. Researchers can use this information to develop transgenic crops that function more predictablity. This benefits society by reducing the possibility of unintended and undesirable effects of transgenes.

Technical Abstract: Transgenes have great potential in crop improvement, but relatively little is known about the epistatic interaction of transgenes with the native genes in the genome. Understanding these interactions is critical for predicting the response of transgenes to different genetic backgrounds and environments. We examined the expression of two transgenes that produce the marker protein Green Fluorescent Protein in the endosperm of transgenic maize, one of which was driven by the 27kDa gamma zein promoter and the other was driven by a 19 kDa alpha zein promoter. Expression of both transgenes was significantly decreased in kernels containing the opaque2 mutation relative to wild-type translucent kernels produced on the same ear. Examination of levels of the native zein proteins in the kernels analyzed for florescence showed that the native genes that the transgene promoters were based on were reduced as well, establishing that transgene expression mirrored expression of the native gene that contributed the promoter of the transgene.