Joel was asking for some thoughts on an article in /The New
Scientist/ that he saw this week:
> I just finished reading a New Scientist article (which can be accessed
> at http://www.newscientist.com/ns/19991120/newsstory4.html)
> which presents that "the bacterial enzyme that imparts resistance to
> glyphosate (in soybeans) affects a major metabolic pathway in the plant
> has the side effect of sending lignin production "into overdrive".
> The article suggests that as a result of elevated lignin content or
> possibly other unintentional structural changes, glyphosate resistant
> soybean plants are more brittle and prone to structural damage when
> subjected to heat stress than non resistant beans.
I don't know whether this is pertinent, but I was thinking through
some glyphosate/GMO/food issues in September and formulated some
thoughts for someone I was corresponding with. I've appended a
portion of that below, between the wiggly lines.
Could this reported "overdrive" have anything to do with this:
The gene sequence that carries the glyphosate resistance factor in
Roundup Ready soybeans comes from the bacterium /Agrobacterium
tumefaciens/, does it not? That's the bacterium that causes crown
gall, a plant tumor.
What is the tissue structure of a gall? Is it ligneous? As they age,
they're described as "woody" or "spongy."
Below are some more technical details on what I found when I went
a-spading on the issue of how glyphosate works in Roundup Ready
soybeans, during the late summer of this year. I would welcome
corrections from anyone.
[Glyphosate] disrupts an important, basic metabolic pathway that is
present in fungi, microorganisms, and plants: the Shikimate pathway.
The Shikimate pathway is an amino acid pathway. It produces the
aromatic amino acids phenylalanine, tyrosine, and tryptophan.
Glyphosate disrupts this pathway, causing the stunting or death of
The Shikimate pathway's chemical reaction looks like this:
D-Erythrose-4-phosphate + 2 Phosphoenoylpyruvate + NAD+ + NADPH + ATP
---> Chorismate + NADH + NADP+ + ADP + 4 Pi
[So let's imagine we have two different plants.] We have one plant
that, if glyphosate is sprayed on it, it dies, because an essential
metabolic cycle (i.e., set of chemical reactions in its cells) is
disrupted by the glyphosate.
And one plant that, if glyphosate is sprayed on it, doesn't die
because...well, we don't really know why, because Monsanto considers
that proprietary information, and the federal regulators in the US
and Canada have gone along with that. That is, the corporation's
scientists have tinkered with an extremely ancient cellular
chemistry, common to many thousands of organism species, but
apparently patent protection is more important than public knowledge
of how exactly how cellular communication has been modified. (I have
a separate set of concerns about this...another time.)
But apparently it works something like this: one gene inserted in the
GM soybean expresses an enzyme that degrades the glyphosate, while
another gene provides a kind of bridging activity for the disrupted
Shikimate pathway. So the plant gets its amino acids in another way.
The genes that make these two mechanisms possible come from a
bacterium. Is it /Agrobacterium tumefaciens/? I know that's the one
used in Roundup Ready canola. /A. tumefaciens/ is what causes crown
gall. Here is Ohio State's info sheet on that:
Monsanto assures us that they have removed the transfer DNA portion
of these genes that causes tumor formation or virulence, and that
they have replaced them. Sounds like Monsanto believes it has mapped
the genome of this entire organism, and knows exactly where all the
potentially negative genes are and how they work. Which is something
I wouldn't bet my own personal planet on, not because of Monsanto
being what it is, but because of 4 billion years of terrestrial life
being what it is.
We now have two plants. One that acts like a plant that has evolved,
over 4 billion years of terrestrial life, whose metabolism works in
concert with that vast life history. And one that has splices and
glitches in its metabolism, chunked out from a tumor-causing
bacterium, and acts in a completely novel way--a way that evolution
would have been hugely unlikely to have developed. (Evolution is a
notoriously non-capitalistic energy flow; things rarely change on
their own in support of proprietary or commercial activity, which are
human values. What evolution's values are, no one knows, though
there's been a lot of speculation.)
Center for Integrated Ag Systems, UW-Madison
UW voice mail: 608-262-8018
Home office: 415-504-6474 (504-MISH)
Home office fax: Same as above, phone first for enabling
Prometheus, you are glad that you have outwitted me and stolen
fire...but I will give men as the price for fire an evil thing in
which they may all be glad of heart while they embrace their own
destruction. --The god Zeus, in Hesiod, /Works and Days/ 55
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