Re: BIOTECH: micronutrient rice (fwd)
Robert J. Bradbury (bradbury@www.aeiveos.com)
Mon, 23 Aug 1999 12:30:31 -0700 (PDT)
> Brian D Williams <talon57@well.com> wrote:
> I couldn't agree more. I'm not interested in biotech crops whose
> purpose is to be able to successfully douse the fields with
> "Roundup", in fact I oppose such bioengineering.
Careful... There are a couple of problems here -- At least
in my Biology class when they went through plant biology they
indicated that Roundup *only* affects plants, doesn't impact
animals at all because we don't have those biochemical pathways.
So if you were saying that you didn't like herbicides because
of health effects, you are stepping on the wrong beast with Round Up.
If you were saying that you didn't like engineering crops
so some would resist Round Up, I suppose that depends on
what other methods of weed control you can cost effectively do
and how much you don't like companies making money off of their
inventions.
> I have a hunch this will backfire anyway as plasmid transfer
> renders the weeds immune as well.
But science doesn't stand still. You can probably keep
engineering genes that render the crop plants "immune" to
whatever toxin you want to dump onto the weeds. We just
aren't at the point where we can do it in such a way that
it is a multi-gene system, in multiple places in the genome
so it doesn't transfer easily. Ideally you would like to
be able to run through the field, vaccinate all the crop
plants and dump a lethal virus on the weeds all in one
sweep.
> I'll take a Brandywine tomato over a "flavrsavr" anyday...
If you are saying home-grown vs. industrially farmed, I
would agree.
Re: engineering out toxins
> I suspect such crops would do poorly in the field, you can make a
> good case that we have evolved (except in Kansas) the abilty to
> deal with these "natural" toxins.
This is true, but it all has to do with dose-response. Our responses
may be able to deal with a "typical" dose, in that the accumulated
lifetime risk only causes cancer in someone at an average age of 80.
Natural selection could not vary our detoxification levels to allow
us to get to 120 because before we never got to 80. There is
actually a fairly large amount of genetic variation in humans
in these areas. The general rule is that if a gene didn't impact
your reproductive fitness before probably age 30, then nature
has probably let lots of variations creep into it. We never got
high doses of toxins historically because we learned (either
genetically or from our tribe) what the really bad ones were.
Our genome breeding efforts to reduce toxin levels is way behind
our plant breeding efforts to increase toxins.
What you really want to do is engineer the plants with something like
a Bt-toxin that is highly specific for whatever insect pests bother a
specific crop type. You want it to be highly insect specific and
completely nontoxic to humans. Fortunately there is enough
difference between insects and humans genetically that I would
hold out some hope for this.
> I don't know how much lab work we really need. New companies like
> SOC not only save and reproduce heirloom seeds, but breed new
> varieties. Millions of backyard experimenters sound's like a better
> way to go.....
This sounds like the self-evolving AI approach (bottom-up).
I favor the top-down approach when you know exactly what the genes
(or gene-produced chemicals) do. I would agree that preserving
native genomes is a very useful thing to do because they all
have some interesting and special features that we may one
day want to make use of. Saving the old ones is much easier
than inventing new ones.
Robert