The Cauliflower Mosaic Virus promoter - a hazard in GE plants

(The text below is a condensate of a scientific article, "The use of cauliflower mosaic virus" by professor Joe Cummins. The scientific references have been left out here.)

The majority of crop plant constructions for herbicide or disease resistance employ a promoter from Cauliflower Mosaic Virus (CaMV). Regardless of the gene transferred, all transfers require a promoter, which is like a motor driving production of the genes' message. Without a promoter, the gene is inactive, but replicated. CaMV is used because it is a powerful motor.

The CaMV promoter normally drives the creation of copies of the CaMV-virus. This virus contains RNA which is similar to HIV, Human Leukemia Virus and Human hepatitis B. CaMV is closely related to hepatitis B and is closely related to HIV (the AIDS virus).

The CaMV promoter is preferred above other potential promoters because it is more powerful than others and is not greatly influenced by environmental conditions or tissue types.

The perceived hazards of the CaMV promoter in crop plants include the consequences of recombination and pseudo recombination. Recombination is the exchanges of parts of genes or blocks of genes between chromosomes. Pseudorecombination is a situation in which gene components of one virus are exchanged with the protein coats of another. Frequently viruses may incorporate cellular genes by recombination or pseudorecombination. It has been noted that such recombinants have selective advantages.

It has been shown that the CaMV DNA incorporated into the plant (canola) chromosome recombine with infecting virus to produce more virulent new virus diseases. The designers of the experiment questioned the safety of transgenic plants containing viral genes.

Recombination between CaMV viruses involves the promoter and may take place either between DNA and DNA or RNA and RNA and frequently creates more severe infections than either parent. Recently related experiments suggest altered plants may breed deadlier diseases. DNA copies of RNA Viruses are frequently propagated using the CaMV promoter to drive RNA virus production

Present in every cell

Viral genetic elements introduced through genetic engineering are present in every cell of GE plants. A corn plant, for example, contains about a billion cells. Even if the statistical risk for the creation of a dangerous virus would be exceedingly small, still it may be likely to occur because of the enormous numbers of recombination-prone virus elements in the total annual crop. For more, see The Virus Hazard  [EL]