LATEST
CIMMYT SCREENS OF MEXICAN MAIZE LANDRACE MATERIALS FIND NO PRESENCE OF PROMOTER
ASSOCIATED WITH TRANSGENES
3 May 2002
El Batan, Texcoco, Mexico—As part of their
continuing effort to characterize maize gene bank accessions and breeding
materials, scientists from CIMMYT's Applied Biotechnology Center and Maize
Program recently conducted another set of screens aimed at detecting the
presence of transgenes in an additional 28 Mexican landraces. None of the
materials tested were positive for the common transgenic promoter (cauliflower
mosaic virus 35S, abbreviated as CaMV 35S) associated with transgenic maize. If
the promoter had been found and those results verified, it would have indicated
that a transgenic maize plant had crossed with the sampled maize or a direct
ancestor.
Seed for all 28 landraces was collected in the
Mexican state of Oaxaca during 1997–99; 18 of the samples come from accessions
maintained in CIMMYT’s maize germplasm bank—part of the Wellhausen-Anderson
Plant Genetic Resources Center—and are designated as being held "in
trust" for the benefit of humanity under a 1997 agreement with FAO, which
means they must be kept free from any intellectual property restrictions (such
as patents). The other 10 samples represent varied maize races from the Mixteca,
a region in southeast Mexico that includes parts of Oaxaca and Puebla states. To
date, CIMMYT specialists have screened 152 Mexican landraces and failed to
detect the presence of the CaMV 35S promoter
Seeds of 28 Mexican maize accessions were received
from Dr. Suketoshi Taba, head of the CIMMYT Maize Gene Bank. These seeds were
germinated and DNA extracted according to the standard protocols of CIMMYT’s
Applied Biotechnology Center (ABC). DNA was amplified using a primer
corresponding to the CaMV 35S promoter, a fragment of DNA found in most
commercial transgenic maize and not known to exist naturally in the maize genome
(sequence available upon request). DNA was extracted in a bulk of 10 plants, and
a total of 10 plants were tested per population. DNA isolated from a known
transformed plant containing the CaMV 35S promoter was run as a positive
control. To further ensure that the reactions were working correctly, all DNA
samples were amplified using a primer corresponding to a fragment of DNA known
to exist naturally in the maize genome. All positive controls amplified
correctly, and no bulk of gene bank maize amplified the CaMV 35S promoter
sequence, indicating that, in the samples tested, there is no CaMV 35S promoter
sequence.
For more information, contact the Director of
CIMMYT's Applied Biotechnology Center, Dr.
David Hoisington, at d.hoisington@cgiar.org
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This document was prepared
in English, and a Spanish translation has been prepared for
informational purposes. In the event of any inconsistency between the
different versions, however, the English version should be considered
the authoritative text. |
August, 2004