Dr. Donald Frederikson 
- 2 - 
April 20, 1978 
accountability. Fortunately, plasmid biology and recombinant DNA 
technology offer a short cut to doing genetics with un characterized 
species. These techniques allow one to investigate those characteristics 
unique to a species without wasting time repeating experiments that 
have already been done with E^. coli . If recombinant DNA research 
with plant pathogens is not deregulated as fully as possible, then 
workers in this field will be required to either generate background 
data and documentation in order to get approval of an MUA or demonstrate 
gene exchange to prove that their organisms are exempt from regulation. 
In either case, there will be delays and the advantage of using 
recombinant DNA technqiues will be decreased. I fear that many 
qualified researchers in the agricultural sciences may not be able to 
afford or justify this time and effort and consequently some scientifically 
interesting and economically important systems will remain unstudied, 
certain aspects of my own research on Stewart's wilt of corn being a 
case in point. For this reason, I recommend that the committee define 
gene exchangers (La Jolla Group Recommendation IV) as those species which 
exchange any plasmids (or at least prime plasmids) so that the majority 
of plant pathogens will be exempt from the guidelines. 
If, however, a narrow definition of gene exchangers is necessary 
for theoretical or safety reasons, then reconsideration of two other 
proposed restrictions would be advisable: 
1) According to La Jolla Working Group Recommendation III self- 
cloning will be exempt only if carried out with indigenous vectors. 
I feel that the use of specific EK1 and EK2 certified vectors should 
be exempted in those species that exchange plasmids with E_. coli . 
Developing new vectors for each species will be a time consuming 
and wasteful task when good vectors already exist. Since R factors 
do not occur in plant pathogens (only because antibiotics are not 
widely used to treat plant diseases) , finding vectors with good 
selectable markers may be difficult. Furthermore, if self-cloning 
experiments are deregulated, there will not be the impetus to characterize 
and test the safety of these new vectors as thoroughly as those already 
certified in .E. coli have been. 
2) Self-cloning will not be possible in species which contain 
ubiquitous cyptic plasmids or are not transformable. In this case 
the DNA must be cloned into E. coli and the recombinant molecules 
reintroduced back into the host of orgin by transduction or conjugative 
mobilization. Such experiments are important and are not possible under 
present requirements for HV systems. 
[Appendix A — 288] 
