It is potentially dangerous. It is inserted into transgenic plants in a form which is different to its naturally ocurring state arising in its natural brassica plant hosts. This enables it to operate in a wide range of host-organism environments which would otherwise not be possible. This page provides more information on this specialist area of genetic engineering risk. At present, the success of transgene expression is variable, and many transformation experiments have to be carried out in order to isolate a small number of useful lines.
Many factors can influence the behaviour of foreign DNA when it integrates into the plant genome.
This allows recombination to occur, as shown by the green arrow. Analysis of junctions between genomic and transforming DNA, and between individual plasmid molecules at integration sites, demonstrates the predominance of microhomology-mediated illegitimate recombination events involving regions with secondary structure. One such region occurs in the CaMV 35S promoter , widely used to drive transgene expression in plants. Probably the greatest threat from genetically altered crops is the insertion of modified virus and insect virus genes into crops. It has been shown in the laboratory that genetic recombination will create highly virulent new viruses from such constructions.