Dr. Fredrickson 
2 
December 6, 1977 
plant pathogenic bacteria and virus to equal those for fungi and nematodes. 
Namely, P2+EK1 or P1+EK2 for shotgun experiments. 
The second change that should be made pertains to purified DNA experiments 
(III B l.c.). Plasmid DNA should not be excluded from those purified DNAs 
that allow one to reduce the containment level. The Agrobacterium tumefaciens 
system has clearly demonstrated that plasmid genes alone cannot change _E. coli 
into a plant pathogen. Therefore, if the A. tumefaciens plasmid is adequately 
purified from chromosomal DNA, there is no danger in cloning parts of it in 
Eh coli at a level of P1+EK1. Further, I believe that the Guidelines should 
include a mechanism to completely remove cloned DNA combinations from coverage 
by the Guidelines as data accumulates to show there is no danger. 
Finally, I would strongly recommend that a subcommittee be formed to deal with 
plants and plant pathogens and make specific recommendations for revision of the 
Guidelines . 
Sincerely yours, 
John D. Kemp, USDA Research Chemist 
/ and Professor of Plant Pathology 
cc 
Dr. Peter Day, New Haven, Connecticut 
Dr. M-D. Chilton, Seattle, Washington 
Dr. Gerald Still, Beltsville, Maryland 
[Appendix A — 103] 
