Report by Recombinant DNA Committee 
AMERICAN SOCIETY OF PLANT PHYSIOLOGISTS 
The proposed revised guidelines for recombinant DNA research (Federal 
Register Friday August 28, 1978) contain appropriate provisions for many 
important experiments. However, the situation in regard to experiments in- 
volving plant DNA has still not been as extensively considered as one might 
wish. Relatively few plant scientists are in a position to use recombinant 
DNA techniques, but the potential benefits to mankind from plant genome 
modification are as great as are those from animal genome modification. For 
example, the enhancement of seed protein quantity, quality, and of photo- 
synthetic efficiency, is highly desirable as is also the widely-considered 
potential for genetic engineering of crop plants to enable non-legumes to 
fix atmospheric nitrogen. 
Although the use of DNA viruses in plants is considered in the proposed 
guidelines (pg. 33081), the use of the Ti plasmid of Agrobacterium tumefaciens 
(crown gall) received scant attention. This is unfortunate since it probably 
represents the most useful potential vector for genetic engineering in plants. 
Under the proposed guidelines (pg. 33089) insertion of DNA from EL coli 
and several other prokaryotes into Ti plasmid is permitted without restriction, 
but no insertion of eukaryotic DNA is allowed. The only basis for such a differ- 
entiation would be an ability for the Ti plasmid to conjugate with EL coli or 
other microorganisms. Deletions Tra ~ in the Ti plasmid are available (J. Schell, 
personal comm, to J.D. Kemp) that render it non-conjugative. Hence, we believe 
that the Agrobacterium- Ti plasmid host-vector system is entirely safe for cloning 
plant DNA. Section III-B of the proposed guidelines (pg. 33080) provides the 
mechanism for obtaining approval for prokaryotic cloning systems. We recommend 
that all Agrobacterlum -Ti plasmid combinations with a Tra ~ deletion be quickly 
approved as HV1 systems. 
Because of the importance of evaluating the possibilities for genetic 
engineering of crop plants, we think it important to include directions for 
the use of the Ti plasmid of Agrobacterium tumefaciens in the revised 
guidelines. In consultation with Dr. Kemp (Plant Pathology Department, Univeristy 
of Wisconsin, Madison) we have developed the following suggestion for the use 
of crown gall as a host-vector system. Since there is no evidence for the trans- 
mission of axenic plant tumors induced by Agrobacterium tumefaciens , crown gall 
is a safe host-vector system for eukaryotic recombinant DNA studies. Therefore, 
we recommend that the following underlined parenthetical phrase and the under- 
lined sentence be inserted in Section III-C-4 (pg. 33084) : 
III-C-4. Plant Host-Vector Systems Other Than Viruses . 
Organelle, plasmid (including Agrobacterium Ti plasmids), and 
chromosomal DNA's may be used as vectors. DNA recombinants formed between 
such vectors and host DNA, when propagated only in that host (or closely related 
strain of the same species) , are exempt from these Guidelines (see section I-E) . 
DNA recombinants formed between such vectors and DNA from cells other than the 
host species require P2 physical containment. Inoculation of hosts with HV1 
approved Agrobacterium containing the DNA recombinants requires P2 physical 
containment . The development and 
Timothy C. Hall, Department of Horticulture Joseph C. Polacco, Department of Genetics 
University of Wisconsin (Chairman) Conn. Agricultural Experiment Station, 
New Haven 
[A-229] 
