Embryology Research Today is a free monthly online journal that collates and summarizes the latest research about Embryology, including details on stem cells, reproduction, transplants, cloning. | ||||||||
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Construction and evaluation of a maize chimeric promoter with activity in kernel endosperm and embryo.Shepherd CT, Scott MP
Chimeric promoters contain DNA sequences from different promoters. Chimeric promoters are developed to increase the level of recombinant protein expression, precisely control transgene activity, or to escape homology-based gene silencing. Sets of chimeric promoters, each containing different lengths of DNA from the maize 27kDa gamma zein (27zn) endosperm-preferred promoter and the Globulin-1 (Glb1) embryo-preferred promoter were created and tested in a transient expression assay of green fluorescent protein (GFP). Promoter fragments with the highest activity were combined to create the chimeric promoter A27znGlb1. In the context of the chimeric promoter, the selected Glb1 promoter fragment was necessary and sufficient to activate expression in embryo tissue and was functionally equivalent to the native Glb1 promoter. Similarly, the selected 27zn promoter fragment in the chimeric promoter was necessary and sufficient to activate expression in endosperm tissue and was functionally equivalent to the native 27zn promoter. Maize transgenic plants containing the A27znGlb1 chimeric promoter fused to GFP were produced to characterize this promoter in vivo. Quantitative reverse transcriptase PCR was used to determine that the promoter was active in the embryo, endosperm, pericarp, and immature leaf tissues. GFP activity in plants containing the chimeric promoter was not significantly different in endosperm than the activity of GFP fused to the full-length 27zn promoter, nor was it different in embryo than the activity of GFP fused to the full-length Glb1 promoter. Transgene copy numbers were shown to be between 4 and 12 copies in different events. Published 16 July 2008 in Biotechnol Appl Biochem.
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