site-specific DNA recombination systems such as bacterial phage and Saccharomyces
cerevisiae systems have been used to excise marker genes or short spacer sequences
in higher plants. They function through interactions of a recombinase with
its specific recognition sites: recombinase recognizes these flanking recognition
sites and excises any intervening DNA.
A new technology called "gene-deletor" or "GM-gene-deletor” has recently been developed by Li and his coworkers at the University of Connecticut. Based on examination of more than 25,000 progeny per transgenic event, it has been demonstrated in tobacco as being 100% efficient for deleting all functional transgenes from both pollen and seeds.
The flow of transgenes into the wild via pollen and seeds remains a concern for some people as well as some scientists. Although no evidence has emerged, there are concerns that novel proteins in certain transgenic crops might cause adverse reactions in some individuals.
The gene-deletor technology could be used to remove all transgenes from any organs of a transgenic plant when the functions of transgenes are no longer needed or their presence may be undesirable for other reasons. The technology may provide a useful tool to address transgene flow problems as well as food safety concerns with regard to transgenic crops.
1. Gene-deletor: a new tool to address concerns over GE crops (June 2007). ISB News Report (http://www.isb.vt.edu/news/2007/news07.jun.htm#jun0701). The full article may be downloaded from this website.
2. Gene-Deletor: A Better Tool Than the Terminator Technology (2007). Gene-Deletor.net (http://gene-deletor.net)
3. Luo K, Duan H, Zhao D, Zheng X, Deng W, Chen Y, Stewart CN Jr, McAvoy R, Jiang X, Wu Y, He A, Pei Y and Li Y. (March 2007). 'GM-gene-deletor': fused loxP-FRT recognition sequences dramatically improve the efficiency of FLP or CRE recombinase on transgene excision from pollen and seed of tobacco plants. Plant Biotechnol Journal, 5 (2), 263-274.