Construction Of Plant Transformation Vector To Excise The Selectable Marker Using Inducible Cre/loxP Recombination System

With the fast enlargement of field application and increasing commercial use of genetically modified crops, the general public have been concerning about the safety of transgenic crops. In 2007, the cropping area of transgenic crops has been up to 2 824 million acres with a growth rate of 12 percent, and 23 countries have made use of transgenic crops. However, as the chosen selectable marker genes, whick confer resistance to certain selective chemical agents, such as antibiotics or herbicides, are becoming a public focus, due to their possible environment and health hazard, eliminating selectable marker genes from transgenic plants have become a serious problem to be solved.Based on Cre/loxP removing system and chemical-induced GR system, an induced Cre/loxp self-removing-antibiotis plant expression vector was constructed. This vector contains a site-specific Cre recombinase gene fused with ligand binding domain (LBD) sequence from a glucocorticoid receptor gene, which was inserted into the two loxP sites of same orientation together with a selectable marker for hygromycin resistance. To prevent Cre recombinase from expressing in prokaryotes, a 346bp intron of CRY1 from Arabidopsis thaliana was inserted within Cre recombinase gene. In order to reduce expression level, nopaline synthase gene (nos) promoter was chosen. Therefore, we had constructed the plant transformation vector which is induced by dexamethasone to remove antibiotics gene using Cre/loxP system. The work may be applicable in further research in the induced excision of the selectable Marker from transgenic plant. The functional identificaton of the vector is in progress.