Finding Transgenes in Maize Landraces

In another project that I lead, biodiverSEEDy, we have been doing some work to see if transgenes have spread to landraces in the center of origin and diversity of maize, Mexico.

The potential for transgene flow into both landraces and wild relatives is a well recognized biosafety issue and therefore an important component of the regulatory risk assessment performed on GM crops prior to their approval for cultivation. The case of transgene flow into traditional maize landraces was first reported in Mexico 15 years ago and drew the world’s attention to the possibility of contaminating crop varieties at their center of origin and diversity.

The reported presence of transgenes in Mexican maize sparked an intense scientific, political and environmental dispute over the extent to which the culture and traditions of indigenous people were being threatened by the unchecked spread of GMOs owned as the patented inventions of multinational corporations. This controversy lead to a long-standing legal battle over the regulatory status of GM crops in Mexico, which continues today as approvals of GM maize for cultivation remain subject to contestation in the courts.

Although maize is currently not permitted for cultivation in Mexico, in a recently published study, we found transgene contamination of landraces being grown by indigenous farmers, as well as maize being sold in government stores as grain, which some farmers then plant as seed. This study also demonstrated how societal organization and the seed management systems of local communities significantly influence the extent and frequency of transgene flow. The work showed how socio-biological factors (such as seed saving and sharing practices, communitarian organization and land tenure arrangements) are highly important determinants affecting the frequency of transgene presence and the potential for spread within farming communities. In doing so, the work also highlighted how social practices and arrangements may be used as a resource to minimize the potential for or scale of transgene flow.

In debates over transgene flow into landraces of maize in Mexico, there has been significant scientific disagreement over what are appropriate and reliable methods to use for GM detection. The use of diverse approaches and a lack of harmonized methods specific to transgene detection in landraces have generated both positive and negative results regarding GM contamination of Mexican maize over the years. In a second newly published paper, we reviewed the scientific debate over methods for detecting transgenes in landraces and wild relatives and made recommendations for sampling, testing and policy. We used this review to inform our own approach to trasngene detection in the work described above. Some of the recommendations we made include: an integration of social and biological data, development of threshold levels and limits of detection relevant for environmental monitoring of low level presence, and the establishment of a public registry with open access to transgene sequence information and all event approvals.

Both of these new papers seek to advance the establishment of good practices for transgene detection and monitoring, issues that are also very important in the contexts where the Agri/Cultures Project is working (Spain and South Africa), as well as anywhere that there is an attempt to achieve co-existance between GMOs and other cultures of agriculture.

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