Dr. Donald S. Fredrickson 
Page 2 
January 3, 1978 
and maintenance in plants. Furthermore, A. tumefaciens is the 
only phytopathogenic bacterium that can be adequately controlled 
both by chemical (non-antibiotic) means and, more significantly, 
by biological means. Biological control by certain A. radiobacter 
strains has proved economically effective on a variety of crops, 
both in this country and abroad. 
3. The letter by Kado et^ al. (Dec. 5, 1977) suggesting a classification 
of plant pathogenic bacteria akin to the CDC classification is an 
admirable first step in such a classification. It should serve 
as a point of departure for further discussion, (there are several 
areas of potential disagreement) , and such a document should include 
viruses, fungi, and potential transcripts of viroids. 
4. Of the potential for agriculture of recombinant DNA technology 
is to be realized, alternate host-vector systems should be encouraged. 
It is unlikely that agriculture would best be served through the 
use of Eh coli (or 13. subtilis ) . 
5. Risk assessment experiments with plant pathogens should be considered 
under the proposed exemption clause. Pathogens of low virulence or 
pathogens of non-economic crops might serve as models for such 
experiments. U.S.D.A. support should be sought for such a task. 
6. Although premature, consideration should be given to the mechanism 
for eventual release of plant material altered by means of in vitro 
recombinant DNA, into the environment. As others have pointed out 
previously, if benefits are to be realized in agriculture, plant 
material must be propagated outside the laboratory. 
7. The most immediate benefits from recombinant DNA to industry seem 
to be in antibiotic amplification, rare drug production, and certain 
hormones. If these are to be produced at affordable cost to consumers, 
industrial and proprietary rights must be considered. Along these 
lines, I believe the specific advice of a patent attorney would be of 
value to NIH, before final revision of the proposed guidelines. 
Finally, I appreciate your concern that the guidelines are deficient in 
treatment of plants (and insects) and their associated microorganisms. However, 
I believe we presently lack the data base to consider more detailed benefits and 
risks beyond those already covered in the revised guidelines. 
In summary, with the exception of minor points, the revised guidelines 
appear satisfactory for the plant sciences. 
Sincerely yours 
Anne K. Vidaver 
Associate Professor 
xc : Peter Day 
John Fulkerson 
Milton Zaitlin 
Clarence Kado 
Arthur Kelman 
Charles McCarthy 
Waclaw Szybalski 
[Appendix A — 176] 
