Genetically-modified plants are now widely cultivated in North and South America, and to a lesser extent in Asia. In Europe, only a few tens of thousands of hectares of Bt maize have been sown in Spain and France. The regulatory provisions of Directive 2001/18 reinforced the prior evaluation of GMOs, fixed rules concerning traceability and labelling and imposed post-marketing biomonitoring. Furthermore, the European Commission laid down general rules defining the context for the co-existence of different types of agriculture: "to ensure that each farmer can make a practical choice between conventional, organic and genetically modified (GM) crop production".
The cross-disciplinary European SIGMEA programme, coordinated by Jeremy B. Sweet (National Institute of Agricultural Botany, United Kingdom) and Antoine Messéan (INRA, France) was launched in 2004 in the context of the 6th Framework Research and Development programme, in order to:
• collate and analyse all European data on gene flow and the environmental impacts of the major species concerned by GMOs (maize, rapeseed, sugar beet, rice, wheat),
• analyse the technical feasibility and economic pertinence of co-existence in the principal farming regions of Europe,
• propose public and private sector decision-making tools,
• formulate guidelines regarding management and governance.
The principal results concerning gene flows and the feasibility of co-existence were presented during the meeting in Seville, from November 19 to 21, 2007.
Shared findings on gene flows
More than one hundred datasets arising from different experiments were collated or generated by the SIGMEA programme. Gene flows via pollen over distances of several tens of metres are now well understood for species such as maize or rapeseed. These data have made it possible to improve predictive models concerning pollen dispersal, taking account of landscapes, climate and farming practices. They have also enabled the identification and quantification of long-distance dispersal (several hundreds of metres) for maize, and the crucial role of the persistence of rapeseed regrowth over time.
From generic models to the scale of a landscape
SIGMEA has developed a generic platform to model gene flow at the scale of agricultural landscapes – LandFlow-Gene. For any agricultural plot described using a geographical information system, this platform can test different scenarios of GM introduction, take account of the effects of practices and the climate, and deliver a diagnosis as to the gene flow. The current version is now operational for maize and rapeseed, and could easily be extended to include other species. In addition, the platform could be adapted to take account of other biological fluxes, such as spore dispersal.
A model for crop systems at the landscape scale has also been developed by British colleagues at Rothamsted Research working with INRA in Jouy-en-Josas.
Public and private sector decision-making tools
SIGMEA thus makes it possible to answer questions such as "what will happen, in terms of gene dispersal, if a particular GM organism is introduced into a particular European region?" and "how can crops be organised so as to maintain the fortuitous presence of GMOs in conventional crops within the legal thresholds?"
The different results obtained by SIGMEA show that the probabilities vary, depending on the cropping context and the characteristics of the GMO under study. For maize, it may be sufficient in certain situations to organise separate harvesting (conditional on an agreement between the farmers involved) to comply with levels lower than the regulatory threshold of 0.9%. If not, measures such as allowing intervals between sowing and quarantine distances can be effective, by they are not always easy to apply. In the event of a very high density of maize, or for species such as rapeseed, a geographical separation between GM and conventional crops is the reasonable solution. On the other hand, for sectors such as organic farming – which requires a total absence of GMOs from their crops – co-existence at a local scale is technically impossible in most cases.
In order to make these findings directly accessible to potential users (farmers, local government bodies, decision-makers, etc.) a prototype decision-making system with a user-friendly interface has been proposed (SMAC-advisor). It prefigures a series of decision-making tools for co-existence which will be developed on the basis of the work carried out in the context of SIGMEA, and particularly by INRA.
Thus, without prejudging political decisions (notably concerning fixed thresholds) these results provide a means of determining (for any introduction scenario) the probabilities of gene dispersal, and the methods that must be implemented to minimize them; they thus inform decision-making in this area.
Consolidated international action
Involving 44 partners from 12 European countries, SIGMEA constituted a cross-disciplinary network of skills and expertise (biologists, ecologists, agronomists, statisticians, economists). The skills thus brought together have enabled Member States to benefit from decision-making support. Many of the SIGMEA teams are now involved in the integrated "Co-Extra" project, coordinated by INRA, which aims to analyse questions of co-existence and traceability throughout the agrifood industry.
*GMCC-07: "International scientific conference on coexistence between GM and non-GM based agricultural supply chains". The 3rd International Conference on the co-existence of GM and non-GM agricultural sectors was held in Seville (Spain) from November 20 to 21, 2007.
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