UNIVERSITY OF CALIFORNIA, DAVIS 
BERKELEY • DAVIS • IRVINE • LOS ANCELES • RIVERSIDE • SAN DIECO • SAN FRANCISCO 
SANTA BARBARA • SANTA CRUZ 
COLLEGE OF AGRICULTURAL AND DAVIS, CALIFORNIA 95616 
ENVIRONMENTAL SCIENCES 
AGRICULTURAL EXPERIMENT STATION 
department of plant pathology December 5, 1977 
Dr. Donald S. Fredrickson, Director 
National Institutes of Health 
Department of Health, Education and Welfare 
Bethesda, Maryland 20014 
Dear Dr. Fredrickson: 
Thank you for your letter soliciting comments on the proposed revised Guidelines 
on Recombinant DNA Research. 
We have reviewed the proposed revisions and wish to direct the Advisory 
Committee's attention to a serious oversight in the Guidelines. After dis- 
cussing the revisions, particularly the section concerning prokaryotic 
recombinant DNA, we feel that organisms important in agricultural research 
were not thoughtfully considered by the Advisory Committee. There exists an 
ambiguous statement in the proposed revisions that may affect research in the 
field of agriculture. This statement appears on page 49602 (Federal Register, 
Tuesday, September 27, 1977), second paragraph, under the section "(2) 
Prokaryotic DNA recombinants" which reads: 
"Experiments with DNAs from bacteria that are not extensively 
characterized require P2 physical containment + EK2 host-vector 
or P3 + EK1. Experiments with DNAs from pathogenic species (Class 
2 and plant pathogens, see Appendix B) must use P3 + EK2." 
In this sentence, all plant pathogenic prokaryotes are included with CDC 
(Center for Disease Control) Class 2 animal and human pathogens. We feel 
that the inclusion of all prokaryotic plant pathogens within this containment 
category, which seems to imply they are equally as "dangerous" as CDC Class 
2 organisms, is an arbitrary assumption made by the Advisory Committee. 
As the sentence in the revision now reads, there are no distinctions made 
among plant pathogenic species, unlike the clear distinctions already assigned 
to animal and human pathogenic species by an existing CDC classification 
(Classes 1 through 4 in Appendix B) . 
We, therefore, wish to submit a classification of plant pathogenic species 
somewhat analogous to the set-up of the CDC classification. It must be 
stressed here that the majority of prokaryotic plant pathogenic species are 
mainly of minimal or no economic importance in agriculture. About 10% that 
are of economic importance may be so only in areas where a specific crop is 
cultivated. Otherwise the geographic, climatic and other natural barriers 
restrict a given host to exist or to be cultivated solely in that area. The 
same set of conditions restricts the existence of the prokaryotic plant 
[Appendix A — 98] 
