gene Flow: Implications for Crop Diversity and Wild Relatives

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particularly in the USA – with varieties not approved for humanconsumption have made recent headlines. Cases such as theStarlink corn contamination in 2000 (Kaufman 2000) and ricein the US with multiple transgenic varieties, 3 are just a fewexamples of inevitable gene flow. Nations that do not accept(certain) GMO products have been forced to ban the import ofgrains or foods from these countries, causing a loss of marketsfor farmers and food distributors. Contamination events oforganic crops can affect the premium value and genetic stocks ofthe crops for the affected farmers. Quite clearly, the unintendedspread of transgenes has been a result of cultivation and seeddistribution systems that were never designed for segregation ofparticular crop varieties. Human error and negligence of lawsare also often to blame. Lastly, patent infringement lawsuitsmight be brought against farmers affected by transgene flow,as previously mentioned.As a result of the many documented cases of transgene flow,robust monitoring programmes have been an important initiativefor many countries, especially those with policies limiting GMOsin their food supply. Hence, tracking transgenes has not onlybiological but political implications.3http://www.guardian.co.uk/gmdebate/Story/0,,1884523,00.html and http://www.aphis.usda.gov/publications/biotechnology/content/printable_version/ia_ge_rice.pdf17
Chapter 4Tracking TransgenesAn essential initial component of understanding the ecologicaland environmental impact of transgene flow is first documentingthe movement or presence of transgenes in a population, foodshipment, or processed food item. This involves employingmolecular methods to detect the synthetic transgenic DNAconstructs, or target marker proteins introduced into the genemodifiedcommodity (Holst-Jensen et al. 2003; Nesvold et al.2006).Successful monitoring and surveillance of transgenes in theenvironment or food shipment is reliant on a number of factors.First, one must be able to detect the transgenic sequences orproteins. Therefore a priori knowledge of the genes one islooking for is essential. Further, the gene sequence or proteinone is targeting in the monitoring efforts must be intact and/orexpressing. In addition, the sampling regime, limit of detectionand reproducibility of results can further affect the outcome ofany monitoring efforts, usually leading to false-negative results(Holst-Jensen et al. 2003). Hence, any sampling for GMOs islikely to underestimate the presence and/or frequency of GMDNA in a sampled population. Thus, not detecting a transgenein a sample population is no guarantee that the population istransgene-free (Heinemann & Traavik 2004). Only with a carefulmultifaceted monitoring strategy can the accuracy and precision18
Page 1 and 2: 11Vertical (Trans)geneFlow: Implica
Page 3 and 4: Vertical (Trans)gene Flow: Implicat
Page 5 and 6: Chapter 6.Practical Considerations
Page 8 and 9: Chapter 1IntroductionThe purpose of
Page 10 and 11: Chapter 2Overview of Vertical Gene
Page 12 and 13: and they do not pose a concern, yet
Page 14 and 15: 2.3 In what species or kinds of cro
Page 16 and 17: Identifying the most important comp
Page 18 and 19: that introgression rates of genes f
Page 20 and 21: of transgenic field trials, in fede
Page 22 and 23: A number of important transgene flo
Page 26: of our monitoring efforts be reason
Page 29 and 30: introduction or interaction with ot
Page 31 and 32: 6.2 Context-specific considerations
Page 34 and 35: ReferencesAlvarez Morales, A. (2002
Page 36 and 37: Hauser, T. P., R. B. Jorgensen, et
Page 38 and 39: Ortiz-Garcia, S., E. Ezcurra, et al
Page 40: Titles in the TWN Biotechnology & B

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