The biosafety of genetically engineered plants has been of concernment in society and science in recent years. The issue of 35S promoter of CaMV has been contentious because of its wide use in plant genetic engineering. The debate on the safety and potential risks of the 35S promoter will be discussed here. Some of concerns are expressed about the dissemination of antibiotic-resistance genes and vector backbone sequences. Various methods and strategies are currently being developed for the marker gene excision and elimination of vector backbone sequences from transgenic plants. In this review, the CRE/ lox system which could get rid of the marker geens and vector backbone sequences will be discussed in detail. Advances in the research of the safety assessment of genetically modified plants using the CRE/ lox system will also be described.
董志峰1,2* 马荣才3 彭于发4 管华诗1
（1. 青岛海洋大学，青岛266003；2. 中国生物工程开发中心，北京!100081；
3. 北京农业生物技术研究中心，北京100089; 4. 中国农业科学院植物保护研究所，北京100094）