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DR. FREDRICKSON: As far as we are aware of, you discovered it. The Ti 
plasmid, then, is the only microorganism plasmid to go into plant cells at 
this time. 
DR. CHILTON: Yes. 
DR. FREDRICKSON: And there is a tremendous amount of comment that you 
have probably seen in the Orange Book about that. Some of it, I guess, you 
have generated. Perhaps you can tell us about that in a moment. But Dr. 
Neel I think had a question. 
DR. NEEL: A comment. In a sense, don't we have intellectual parallel- 
ism to a shotgun experiment with plants? We assume that there are two spe- 
cies that you can't cross, but you think there is something desirable in the 
one species that isn't in the other, and you have to get a virus vector that 
will give you the shotgun, and then you stake out all your little plants. 
You look them over and choose what you want. 
Now, in a sense radiation has been used in a shotgun fashion, which in- 
volved disseminated changes in the genetic material, sowed the field, and 
hoped for something that would improve the plant. So there is a sort of an 
intellectual precedent here, it seems to me, in the plant improvement pro- 
grams . 
DR. DUVICK: I think that is right. The main difference there might be 
is that conceptually we could make much wider crosses with these new tech- 
niques than even using radiation here. They must be related taxonomically , 
at least on the generic level, and occasionally on the family level. 
DR. ZAITLIN: With respect to your comment before, Dr. Fredrickson, in 
terms of plant viruses we have no evidence that these viruses become inte- 
grated into the genome of their host. I should preface my remarks, however, 
by saying that they really haven't been looked for too stringently. In the 
case of RNA plant viruses, there have been some experiments which suggested 
there is no insertion or there are no sequences which are complementary to 
the RNA plant virus in the genome of its host. 
DR. FREDRICKSON: You are coming up a little later, Dr. Szybalski, can 
you wait? 
Dr. DeRoos . 
DR. DE ROOS: I was reading in these comments here the letter from Dr. 
Albersheim — 
DR. FREDRICKSON: In the Orange Book of comments, from Dr. Albersheim. 
Yes . 
DR. DE ROOS: The comment about the Guidelines being less restrictive 
for plants, plant viruses in particular, than for example animal viruses, 
and we should be more concerned about plant viruses, particularly since 
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