"... we are confronted with the most powerful technology the world has ever known, and it is being rapidly deployed with almost no thought whatsoever to its consequences"
Susanne Wuerthele Ph.D., EPA scientist
"Genetically engineered crops represent a huge uncontrolled experiment whose outcome is inherently unpredictable ... The results could be catastrophic."
Dr. Barry Commoner, senior scientist
Center for the Biology of Natural Systems at Queens College of New York
Transgenic DNA Introgressed Into Traditional Maize Landraces in Oaxaca, Mexico
David Quist and Ignacio H. Chapela
Department of Environmental Science, Policy and Management
University of California
Berkeley, California 94720-3110, USA
(Correspondence and requests for materials should be addressed to I.H.C. e-mail: ichapela@nature.berkeley.edu.)
Concerns have been raised about the potential effects of transgenic introductions on the genetic diversity of crop landraces and wild relatives in areas of crop origin and diversification, as this diversity is considered essential for global food security. Direct effects on non-target species1, 2, and the possibility of unintentionally transferring traits of ecological relevance onto landraces and wild relatives have also been sources of concern3, 4. The degree of genetic connectivity between industrial crops and their progenitors in landraces and wild relatives is a principal determinant of the evolutionary history of crops and agroecosystems throughout the world5, 6. Recent introductions of transgenic DNA constructs into agricultural fields provide unique markers to measure such connectivity. For these reasons, the detection of transgenic DNA in crop landraces is of critical importance. Here we report the presence of introgressed transgenic DNA constructs in native maize landraces grown in remote mountains in Oaxaca, Mexico, part of the Mesoamerican centre of origin and diversification of this crop7-9.
In October and November 2000 we sampled whole cobs of native, or 'criollo', landraces of maize from four standing fields in two locations of the Sierra Norte de Oaxaca in Southern Mexico (samples A1*A3 and B1*B3), more than 20 km from the main mountain-crossing road that connects the cities of Oaxaca and Tuxtepec in the Municipality of Ixtlán. As each kernel results from ovule fertilization by individual pollen grains, each pooled criollo sample represents a composite of 150*400 pollination events. One additional bulk grain sample (K1) was obtained from the local stores of the Mexican governmental agency Diconsa (formerly the National Commission for Popular Subsistence), which distributes subsidized food throughout the country. Negative controls were cob samples of blue maize from the Cuzco Valley in Peru (P1) and a 20-seed sample from an historical collection obtained in the Sierra Norte de Oaxaca in 1971 (H1). Positive controls were bulk grain samples of Yieldgard Bacillus thuringiensis (Bt)-maize (Bt1; Monsanto Corporation) and Roundup-Ready maize (RR1; Monsanto Corporation) obtained from leftover stock for the 2000 planting season in the United States. Using a polymerase chain reaction (PCR)-based approach, we first tested for the presence of a common element in transgenic constructs currently on the market*the 35S promoter (p-35S) from the cauliflower mosaic virus (CMV). The high copy number and widespread use of p-35S in synthetic vectors used to incorporate transgenic DNA during plant transformation make it an ideal marker to detect transgenic constructs10-1.
http://www.saynotogmos.org/mexican_study.htm