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Gene flow and GM crops

Gene flow has and will continue to occur between sexually compatible plant species in agricultural habits. What are the implications for growing genetically modified crops?

  1. Cross-pollination occurs between sexually compatible species /crops. (1,2,3)
  2. Likelihood of cross-pollination is determined by the proximity of sexually compatible crops/plant species and where there is synchronous flowering. (4,5)
  3. Distance viable pollen can travel (6) is influenced by the dispersal mechanism and pollen longevity - both of which are species dependent. (7,8)
  4. Pollination falls off rapidly with distance but that the distance at which pollination is zero is impossible to determine with accuracy. (9)
  5. Consequences of transfer of novel genes from GM crops to weeds depend not only on physical distribution but on the nature of the gene and the biology and ecology of the recipient. (10)
    • Herbicide tolerance unlikely to confer and advantage outside agricultural areas. (11)
    • Insect resistance may confer advantage under certain conditions. (12,13)
  6. Many plant species can be found both as a crop and a weed . Change in habitat may potentially result in the evolution of a weed from a cultivated plant or from a feral that is closely related to a cultivated species. (15,16,17,18)
  7. Chloroplast transformation may reduce likelihood of gene transfer by pollen. (19) However, the potential for horizontal gene transfer may increase. (20)
  8. (21,22)
  9. GM herbicide tolerant plants are no more likely to be invasive in agricultural fields or natural habitats than non-GM counterparts. (23)


  1. Garcia M, Fugueroa CJ, Gomez L, Townsend R and Schoper J (1998) Pollen control during transgenic hybrid maize development in Mexico Crop Science 38 1597-1602.
  2. Arias DM and Rieseberg LH (1994) Gene flow between cultivated and wild sunflowers TAG 89 655-660.
  3. Snow AA, Andersen B and Jorgensen RB (1999) Costs of transgenic herbicide resistance introgressed from Brassica napus into weedy B.rapa Molecular ecology 8 605-615.
  4. Ellstrand NC , Prentice HC and Hancock J (1999) Gene flow and introgression from domesticated plants into their wild relatives. Ann Rev Ecol and System 30 539-563.
  5. Raybould AF and Gray AJ 1993 Genetically modified crops and and hybridisation with wild relatives : a UK perspective. J App Ecol 30 199-219.
  6. Lutman PJ (ed) (1999) Gene flow and agriculture: relevance for transgenic crops BCPC, London .
  7. Squire GR, Crawford JW, Ramsay G, Thompson C and Brown J (1999) Gene flow at the landscape level. In gene flow and agriculture: relevance for transgenic crops p57-64 9BCPC, London .
  8. Cresswell JE, Osborne JL and Bell SA (2002) A model of pollinator mediated gene flow between plant populations with numerical solutions for bumblebees pollinating oilseed rape. OIKOS 98 375-384.
  9. Moyes CL and Dales PJ (1999) Organic farming and gene transfer from genetically modified crops MAFF research report.
  10. Hails R, Reeds M, Kohn DD and Crawley MJ (1997) Burial and seed survival in Brassica napus subspecies oleifera and Sinapis arvensis including a comparison of transgenic and non-transgenic lines of the crop. Proc R. Soc London B. Biol Sci. 264 1-7.
  11. Crawley MJ, Brown S, Hails R Kohn DD and Rees M. 2001 Transgenic crops in natural habitats Nature 409 682-683.
  12. Stewart AN, All JN , Raymer PL and Ramachandran S (1997) Increased fitness of transgenic insecticidal rapeseed under insect selection pressure. Mol Ecol 6 773-779.
  13. Ramachandran S, Buntin D, All JN, Ramer PL and Stewart CN (2000) Intraspecific competition of an insect resistance transgenic canola in seed mixtures. Agron J 92 368-374.
  14. Keeler KH, Turner CE and Bolick MR (1996) Movement of crop transgenes into wild plants in herbicide resistant crops - Agricultural, Environmental, Economic, Regulatory and Technical aspects 303-330 (Lewis Publishers London).
  15. National Research Council 2000. Genetically modified pest protected plants: science and regulation (National Academic press Washington).
  16. National Research Council 1989. Field testing genetically modified organisms: framework for decision (National Academic press Washington).
  17. Ammann K, Jacot Y and Al Mazyard R (2000) Weediness in the light of new transgenic crops and their potential hybrids J Plant Dis 17 19-29.
  18. Boudry P, Morchen M, Saumitou-Lapradep Verent p and Van Dijk H. (1993) The origin and evolution of weed beets : consequences for breeding and release of herbicide resistant transgenic sugar beets TAG 87 471-478.
  19. Daniell H, Datta R, Varma S, Grat S and Lee SB (1998) Containment of herbicide resistance through genetic engineering of the chloroplast genome. Nature biotechnology 16 345-348.
  20. Bertolla F, Nalin R and Simonet P. (2002) In Situ transfer of antibiotic resistance genes from transgenic (transplastomic) tobacco plants to bacteria. Applied and Environmental Microbiology 68 3345-3351.
  21. Moyes Cl, Lilley JM, Casais Ca, Cole SG, Harger PD and Dale PJ (2002) Barriers to gene flow from oilseed rape ( brassica napus) into populations of Sinapis arvensis. Molecular ecology 11 103-112.
  22. Senior IJ and Dale PJ (2002) Herbicide tolerant crops in agriculture: oilseed rape as a case study. Plant breeding 121 97-101.
  23. Gene Flow to Wild Plant Relatives (2001) Council for Biotechnology.
  24. This document is available in pdf and word versions.