Tissue-Specific Transgene Removal and Containment System (TRECS) – a Decade Effort for Enabling Technology in Plant

Gene flow from transgenic into wild cultivars or closely related species could potentially create super weeds or invasive species, which could impact current environmental safety and ecological integrity. Recently, we have proposed, developed and tested a sophisticated tissue-specific transgene removal and containment system (TRECS) to directly address the concern on pollen-, seed- and fruit-mediated gene flow in transgenic plants. TRECS is designed to excise transgene specifically in stamen and carpel primordial cells or tissues using a site-specific recombinase, and later contain the floral tissues that escape from the gene excision event to ensure the produced pollen, seed and fruit totally free of transgene. We demonstrated that TRECS can effectively excise and contain transgene in the floral tissues as evidenced by the generation of the transgene-free pollen, seed and fruit in selected transgenic lines. We also showed that several factors including transgene truncation, enhancer-promoter interaction and epigenetic factor (e.g. siRNA and DNA methylation) influence the TRECS excision efficiency and performance. The detailed analyses of these factors in transgenic plants and their impact will be discussed.