USDA Regulation of Genetic Engineering

Comments from Dr. Cummins 23apr99

Prof. Joe Cummins
e-mail: jcummins@julian.uwo.ca 

I was recently asked to comment on USDA comments supporting their rules on transgenic crops. At least 99% of the commercial transgenic crops incorporate viral genes, either as promoters or to control virus My comments on USDA rules on virus genes in transgenic crops are below. The USDA regulations on crop genetic engineering seems to be based on views of genetic recombination that utterly misrepresent the evidence available and the science of genetics. Their comments on viral recombination totally ignore a wide body of literature on recombination involving virus genes incorporated into crop plants.

Turning to the USDA comments:

1. USDA claims "there has been no report of such a recombination" . I find that comment strange because there is a huge body of studies in that area. Not only is there good evidence but the evidence shows that the recombination is very frequent as many as one in five transgenic plants showing such recombination I list a few pertinent references below:

• Schoez,J. and Wintermantel,W. "Expansion of viral host range through complementation and recombination in transgenic plants" The Plant Cell 5,1669-79,1993.

• Gal,S.,Pisan,B.,Hohn,T.,Grimsley,N. and Hohn,B. "Genomic homologous recombination in planta" EMBO Journal 10,1571-78,1991.

• Gal,S.,Pisan,B.,Hohn,T.,Grimsley,N. and Hohn, B. "Agroinfection of transgenic plants leads to viable cauliflower mosaic virus by intramolecualr recombination" Virology 187,525-33,1992.

• Gal,S.,Pisan,B.,Hohn,T.,Grimsley,N. and Hohn, B. "Agroinfection of transgenic plants leads toi viable cauliflower mosaic virus by intramolecular recombination" Virology 187,525-33,1992.

• Wintermantel,W. and Schoeelz,J. "Isolation of recombinant viruses between cauliflower mosaic virus and a viral gene in transgenic plants under conditions of moderate selection pressure" Virology 223,156-64,1996

• Swoboda,P.,Hohn,B. and Gal,S. "Somatic homologous recombination in planta" Mol.Gen.Genet 237,33-40,1993.

• Borja,M, Rubio,T,Scholtof,H. and Jackson,A. "Restoration of wild-type virus by double recombination of tomusvirus mutants with a host transgene. Mol.Plant MicrobeInteract 12,153-62,1999.

2. USDA claims " that although recombination could theoretically occur, it would have to be between two 2 viruses which already affect the host plant (the virus providing the engineered gene and another virus which would infect the engineered plant in the field)".
   
   The USDA view here describes the situation in the many experiments they seem unaware of. However, the plant virus nucleic acid such as the DNA of many plant pararetrovirus may be propagated in insect baculovirus. Recombination involving insect virus , or for that matter the viruses of higher animals ingesting plant material engineered to contain virus genes should not be ignored.
   
   

3. USDA claims "such recombination could or would have already occurred in the field naturally". All recombination taking place in the field is natural while gene cutting and splicing in the laboratory is unnatural. Certainly "such" recombination already occurred in the field. However, it is clear that the frequency of recombination to create new genetic variations leading to enhanced virulence of the virus is increased by orders of magnitude when virus genes are present in every cell of every plant in a crop planted to millions of acres.
   
   

4. USDA finally claims "but such recombination is so rare (occurring on an "evolutionary" time scale) that the event is of vanishingly low probability" The last USDA comment suggest the agency may be part of a bureaucratic never never land run by people who believe that nature must follow the rules of USDA. The USDA comment is truly bizarre , it ignores the many studies showing high rates of recombination of viral genes in transgenic crops.
   
   Clearly the USDA regulations should be changed to reflect true scientific facts not the desires of agricultural bureaucrats.