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Re: [SANET-MG] Reproductive isolation in hybrid seed production



Hi Dale,
I think the "asynchronous" fields should have been and should be studied. Such fields are part of the real world of corn and they have a story to tell. They should not be presumed to be contaminated or not until they have been studied. It is a very uncomfortable situation to have used some fields in the study and not others based on an arbitrary and cursory judgment in the field.. You have made a case for hybrid seeds in which the standard for acceptable contamination is a higher percentage than is GM food and feed. The I% or greater level of contamination in hybrids seeds ,if reflective of gm contamination , would mean that none of the corn for export from the the US should pass import standards of 1% or less. At any rate , it is clear that essentially none of the corn grown in the US is free of GM contamination. Presently, I believe that PCR and or ELISA tests are the standard for GM contamination but roundup ready and each of the Bt cry toxins must be measured individually. Currently there is no universal test for GM since the old CaMV promoter test has been been overtaken by a use of a range of promoters. It seems easy to miss GM pollution unless a battery of PCR or ELISA tests were applied. Perhaps a universal test will be invented? Until then it seems probable that GM pollution will continue to be underestimated. Finally, you did not argue against the validity of your hybrid study as a model for GM contamination in corn? Your study was an important one for hybrids in spite of the field selection. I wonder whether or not it will be accepted to be a model for GM contamination of corn?\
sincerely,joe
Dale Wilson wrote:
Hi Joe,

We excluded a dozen or so screwed up fields in which the two inbred parents were not flowering synchronously. In
such cases, a high levelof contamination is likely, no matter what
you do. This is another reason to not buy brand-X seed."

You seem to be confessing that you selected the data from fields
likely to give you the results that were desired.

We decided early on to study fields where seed production was executed
normally.  Obviously, if you have a sterile, or detasseled female
parent flowering, and the male parent didn't come up, or was planted at
the wrong time, The seed borne on the female parent will be heavily
contaminated with pollen that blows in from God-knows-where.
Of course, that selection was not mentioned in the publication...

Yes it is mentioned.  Read it again.

If 5% contamination is good enough for hybrids it certainly is not
for GM contamination.

If corn exceeds 5% contamination by other varieties (GMO or not) it has
to be labeled "Variety not Stated."  Companies I am familiar with have
internal QC limits ranging from 1 to 3% (again, GMO or not).  I have
seen cases where many thousands of bags were discarded because they did
not meet the internal QC standard.  For special markets, companies have
more stringent QC limits specifically for GMO contamination.

The hybrid study suggests that organic and conventional corn may
be far more polluted by GM transgenes than has been allowed for
export to most countries.

Well, Joe, the export standard for GMO for EU is 1%, isn't it?  The
study showed that the actual rate of contamination by off-types
averaged around 1%.  The few seedlots that are much higher than that
are caught by routine QC testing.  Every lot (that is every size grade
of every batch of raw seed) is tested electrophoretically for off-types
before it goes out the door.  Having a heavily contaminated lot slip
through is not likely.

Dale

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