Challenges for monitoring (trans)gene-flow in the environment.

Monitoring the presence of transgenes in the environment depends on analytical detection methods and their measurement uncertainties. In this chapter, we aim to identify key methodological aspects and pinpoint the research bottlenecks and needs for building the capacity to effectively monitor transgene escape from genetically modified (GM) crops to wild relatives or landraces. We reviewed the iconic debate concerning the presence of transgenes in landraces of Mexican maize (with both positive and negative results for GM contamination shown over the years) to examine the impact of using different approaches to monitoring and detecting transgenes in landraces. Despite the lack of clear international guidelines that are specific for sampling and testing heterogeneous and dispersed landraces and wild relatives, transgene detection methods have developed significantly over the past decades. There is now an immensely valuable set of tools, approaches, and harmonized protocols that continue to develop and provide a way to evaluate transgene presence. To support this ongoing development and to steer it in directions that are particularly useful for addressing the challenges associated with detection in landraces and wild relatives, we offer lessons from our review for future work in this area particularly useful for addressing the challenges associated with detection in landraces and wild relatives, we offer lessons from our review for future work in this area.