[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Deep Water



Hi Chuck,
In reply to your points. " First, if Monsanto had a RR soybean variety
that was heterozygous,
it would deep six it because it would not perform with sufficient
reliability, right?  RR soybeans, corn, cotton seed bought by farmers are
homozygous with respect to the RR trait, correct? "
Not entirely correct, there are different strokes for different  folks
(crops). Soy is inbreeding  and likely to be homozygous, to all best
knowledge there are no heterozygous GM soy  and even hemizygous soy
could not be maintained by inbreeding,  canola is out breeding and most
commonly homozygous for transgenes, corn being hybrid is a cross most
frequently between  two inbred lines one of which may not be rr ready
but the product of the cross between homozygous rr corn and non-GM line
is hemizygous  because there are no natural  alleles at the rr locus
(indeed there is so little control over insertion of rr genes that rr
locus is unique and has no alleles at the insertion point). .Try drawing
out the chromosomes and you may see what I mean. I have not yet
encountered a slovenly journal editor  who allowed hemizygous  strains
to be called  heterozygous but such duds may exist.
"  Now, we move deeper into the water when the pollen from a
homozygote RR variety crosses with a non-GMO variety.  The seed produced by
that conventional-non-GMO plant pollinated cross could be heterozygous --
or if I understand Joe, hemizygous -- but never homozygous, or perhaps I
just drowned. "
When pollen from a homozygous RR ready crop  pollutes a non-GMO variety
the product is always hemizygou never heterozygous. When the hemizygous
rr crop fertilizes another non-GM  the progeny are half hemizygous and
have non-GM. If a hemizygous rr hybrid corn  pollutes a non-GM corn
again half the progeny will be hemizygous rr and the other half non-GM.
Under normal circumstances  heterozygous  rr nonGM  do not exist
because  there are no non-GM alleles at the rr locus. Finally, what if
you have a double rr transformation , one of which is silenced, the two
are not allelic thus both are hemizygous.
The use of the terms homozygous, heterozygous and hemizygous  are well
described in most elementary genetics texts, google searches also
provide fast definitions with some diagrams. Nothing very deep is
involved. In passing I should not that  two famous plant breeders,
Luther Burbank and Academician Lysenko, are reputed to have never
learned formal genetics, let us try to discuss genetics even though
breeders can manage without it.
I hope my discussion helped, if Monsanto  wishes to redefine
heterozygous they probably have the cash to swing it!
Sincerely, Joe


Chuck Benbrook wrote:

        Friends, the ongoing dialogue over GM crop genetics is getting
into very interesting deep water. Perhaps if you experts will continue
in a
civil tone and explain things a bit more clearly, several hundred people,
me included, will end up understanding something that has, to date,
escaped
comprehension.  In his last post, Joe said --

"Transgenic crops are either homozygous or hemizygous but practically
never
heterozygous. A heterozygous transgene would normally arise if a
homozygous
diploid suffered a mutational change on one of the alleles to inactivate
the allele or to alter its activity."

        Dale, Joe, and Wyzte -- as the most active participants in this
debate, please proceed in bite sizes, respectful of other (e.g., mine)
ignorance.  Perhaps by thinking through this fascinating issue together,
everyone will end up surviving despite moving a little deeper in the
collective pond of the not yet fully known.

        First, if Monsanto had a RR soybean variety that was
heterozygous,
it would deep six it because it would not perform with sufficient
reliability, right?  RR soybeans, corn, cotton seed bought by farmers are
homozygous with respect to the RR trait, correct?

        Now, we move deeper into the water when the pollen from a
homozygote RR variety crosses with a non-GMO variety.  The seed
produced by
that conventional-non-GMO plant pollinated cross could be heterozygous --
or if I understand Joe, hemizygous -- but never homozygous, or perhaps I
just drowned.

        Before going any deeper, out of a sense of self-preservation,
I am
hoping the experts will explain a bit more fully where we are at.  I
need,
for sure, a little more education on the difference between a
heterozygous
seed and a hemizygous seed.  Please, you experts, lets follow Patrick
Swayze's bouncer rules in "Road House" -- ALWAYS be nice (even when
kicking
some a__hole out he door).






_________________________________________________________________

Charles Benbrook         Ag BioTech InfoNet
<http://www.biotech-info.net>
Benbrook Consulting Services  CU FQPA site <http://www.ecologic-ipm.com>
5085 Upper Pack River Road            IPM site <http://www.pmac.net>
Sandpoint, Idaho  83864
Voice: (208)-263-5236
Fax: (208)-263-7342
E-mail: <benbrook@hillnet.com>

********************************************************

To unsubscribe from SANET-MG:
1- Visit http://lists.sare.org/archives/sanet-mg.html and unsubscribe
by typing in your e-mail address or;
2- Send a message to <listserv@sare.org> from the address subscribed
to the list. Type "unsubscribe sanet-mg" in the body of the message.

Visit the SANET-MG archives at:
http://lists.sare.org/archives/sanet-mg.html

********************************************************

To unsubscribe from SANET-MG:
1- Visit http://lists.sare.org/archives/sanet-mg.html and unsubscribe by typing in your e-mail address or;
2- Send a message to <listserv@sare.org> from the address subscribed to the list. Type "unsubscribe sanet-mg" in the body of the message.

Visit the SANET-MG archives at: http://lists.sare.org/archives/sanet-mg.html