to avirulent mutants and the need to certify new host-vector systems for 
self cloning experiments or so that DNA cloned into coli can be returned 
to its host of origin. Another problem which concerns geneticists, regard- 
less of whether or not they are involved with cloning, is that in vitro con- 
structed plasmids cannot be transferred from IE. coli to other bacteria even 
though they are merely deleted plasmids or have been formed from plasmids 
which have already been shown to transfer to the species in question without 
adverse effect. This greatly limits the genetic tools available to workers 
in other fields. 
As a result of the current restrictions, recombinant DNA techniques have not 
been widely used in the plant sciences. Agricultural workers are often obli- 
gated to divide their efforts between so called basic and applied programs 
and are seldom full time geneticists. They are not in a position to afford 
new containment equipment which up to now has not been needed for their work, 
reallocate space Currently shared with other programs for P2 or P3 facilities 
and devote their time to research for the sole purpose of documenting the 
safety of their host-vector system. 
The revised guidelines eliminate many of the problems mentioned above by 
exempting or reducing the containment required for studies with DNA from 
plants and plant associated microorganisms and viruses. I fully agree with 
the rationale for these changes as presented in the report of The Workshop 
on Risk Assessment of Agricultural Pathogens. If these guidelines are imple- 
mented there will certainly be an increase in the number of plant scientists 
using this technique and the benefits to agriculture could be tremendous. I, 
for one, am not currently working with recombinant DNA but would like to use 
the technique, if new guidelines are implemented, to investigate the association 
between plasmids and virulence in Erwinia stewartii , a pathogen of corn. 
On behalf of other plant pathologists I strongly urge that the proposed Revised 
Guidelines be accepted and implemented as soon as possible so that there will 
be no further delays in beginning important research on genetic improvement 
of plants, nitrogen fixation and plant diseases. 
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