Heat-inducible Cre-lox system for marker excision in transgenic rice
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The present study assessed the efficacy of a heat-inducible cre gene for conditional removal of the marker gene from a rice genome via Cre-lox recombination. A cre gene controlled by the soybean heat-shock promoter was introduced into the rice genome along with the recombination target (lox) construct. Cre-mediated recombination was expected to remove the marker gene and activate the promoter-less GUS gene. Six transgenic lines displayed well-regulated heat-inducible Cre activity in the callus. However, only one line that contained a single copy of the cre gene maintained this property in the regenerated plants and their progeny. Marker-free progeny were obtained from the plant that was heat-treated at the seedling stage, indicating the inheritance of the recombination ‘footprint’. The presence of the ‘footprint’ was verified by polymerase chain reaction and Southern analysis. Therefore, the cre gene controlled by the soybean heat-shock promoter is an effective tool for conditional removal of the marker gene in rice.
KeywordsCre-lox inducible promoter marker removal site-specific recombination transgenic rice
This work was supported by the USDA-CSREES grant (BRAG 2006-33120-17718), and the ABI-Arkansas Division of Agriculture grant to VS. We thank Dr Yinong Yang and Dr David Ow for the gift of HSP promoter and cre gene, respectively.
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