APPENDIX E 
Guidelines for experiments with plant host vector systems . The 
Guidelines also contain recommendations for experiments in which plant 
cells will serve as hosts for recomb i nant DNA . The cells might be single 
plant cells grown under laboratory conditions, or seedlings, plant parts, 
or small whole plants. This is in fact the only instance where the 
guidelines address the question of recombinant DNA experiments with whole 
organisms. Directions are given for modification of the specifications for 
PI, P2, and P3 physical containment in order to provide conditions appro- 
priate for work with plants. 
Vectors for use in experiments with plants include plant organelle DNA 
such as the DNA of ch I orop I asts , and DNA of viruses of low pathogenicity and 
restricted host ranges. These vectors offer moderate levels of biological 
containment, and the guidel ines specify the physical containment levels 
outlined in Table 5. As before, the requirements are organized according 
to the source of the foreign DNA. If the foreign DNA is derived from a 
species in which the vector DNA is known to be able to replicate, P2 condi- 
tions are required, unless the source of foreign DNA is pathogenic or produces 
products dangerous to p I ants. . .then P3 is required. If the foreign DNA is 
derived from a species in which the vector is not known to replicate then 
more stringent requirements govern and vary from P2 to P4 depending on 
whether the DNA is purified, and whether it contains harmful genes. 
Other host-vector systems . Theoretically, there are a variety of organisms, 
both prokaryotes and lower eukaryotes such as fungi and yeast which will be 
interesting and useful hosts for experiments with recombinant DNAs. Some may 
offer the special advantage of not infecting humans, animals or important ecoloqica 
Appendix E — 20 
