THREATS TO BIODIVERSITY THROUGH OUTCROSSING AND GENETIC POLLUTION

  The large-scale growing of genetically engineered crops has given rise to a number of serious concerns including the effects on volunteer and feral populations and wild relatives of the crop. Genetically engineered (GE) oilseed rape is a particular threat since the crop is a member of the Brassica family, which has its centre of origin in Europe. Nine hundred species of the Brassica family can be found in Europe. This means that Europe is an important centre of diversity and there are many related plants growing in close proximity to cultivated oilseed rape. Natural biodiversity could be placed at special risk by gene flow from GE oilseed rape to wild relatives.

  Local cultivars, called "land races", and isolated populations of wild species, are particularly vulnerable to genes crossing out from new crop varieties. Gene transfers could lead to the loss or permanent alteration of these wild species or landraces. Smaller populations might literally get swamped by the incoming genes (Ellstrand 1992). Such hybridisation has been implicated in the extinction of five wild species, including the wild ancestors of maize, hemp, pepper, date palm, and sweet pea (Small 1984). Recent studies suggest that significant levels of gene flow could occur from genetically engineered oilseed rape fields following their full commercial release (Wilkinson et al 1995). Therefore, hybridisation is a major concern with GE oilseed rape when introduced into its centre of origin in Europe.

  If the introduced gene gives a competitive advantage over other plants, for example by enabling the plant to resist diseases or habitat influences such as droughts, the gene is likely to persist and the likelihood of becoming a damaging weed in the ecosystem is increased (Ellstrand et al 1990). This is of particular concern with GE oilseed rape. Studies in France have shown that hybridisation occurs between oilseed rape and hoary mustard (Hirschfeldia incana). It was found that, under competitive conditions, these hybrid plants do better than hoary mustard (Lefol et al. 1995).

  In addition, Danish researchers observed that hybrid plants resulting from crosses between genetically altered oilseed rape and a weedy relative (Brassica campestris) were highly fertile (Mikkelsen et al 1996). Furthermore, genetic modification may result in unintended side effects which can give a competitive advantage. For example, Monsanto's GE tomato for delayed ripening sets more seed than the unmodified parent (USDA/APHIS 1995), and the delayed softening trait in Calgene's GE tomato has conferred increased resistance to fungi which normally infect ripening fruits (Kramer et al 1992). AgrEvo's/PGS's GE oilseed rape contains a gene for herbicide tolerance, a gene for antibiotic resistance, a gene for male sterility and a fertility restoration gene, any of which has the potential to trigger unexpected side effects in the varied environmental conditions in which it will be grown.

  There is also the potential that a transferred gene reduces the fitness of a native plant, leading to the eventual demise of a population. Such an effect has been implicated in the extinction of wild rice in Taiwan. The transfer of genes from cultivated rice could have made the wild rice less adapted to reproduction under varying conditions (Oka 1992). Similar concerns apply to the GE oilseed rape. The GE oilseed rape, although fertile, still carries the male sterility gene together with the fertility restoration gene. It is possible that in case of crossbreeding with another species the gene recombination could not be complete, meaning that part of the transgenes might get lost. For example, only the male sterility gene without the compensating fertility restoration gene could be transmitted, resulting in a male sterile plant which is no longer able to produce pollen. Possible negative effects such as loss of feed for pollen-feeding insects, or threatening endangered plant species by reducing their fitness, cannot be ruled out and have not been assessed.

3.1.1 Gene transfer from GE oilseed rape to related species

  AgrEvo claims that the risk of cross pollination with wild relatives under natural conditions will be minimal (Rasche et al 1995). However, recent research suggests that the risks of cross pollination are significant. Oilseed rape is pollinated by both bees and wind. Scientists at the Scottish Crop Research Institute have show that significantly more pollen escapes from large fields of genetically engineered oilseed rape than is predicted from earlier experiments on smaller plots. They found that escaping pollen fertilised plants up to 2.5 kilometres away (Timmons et al 1994).

  In addition, researchers have found that gene flow occurs between fields of crops sown in the spring and autumn, and between field and experimental feral populations. They conclude that significant levels of gene flow will occur from genetically engineered oilseed rape fields following their full commercial release (Wilkinson et al 1995).

  Studies have shown that gene dispersal from genetically engineered glufosinate resistant rapeseed to weedy species like B. campestris or B. juncea occurred under field conditions after just two generations (Frello et al 1995, Joergensen et al 1994, Mikkelsen et al 1996), suggesting a possible rapid spread of foreign genes from oilseed rape to its weedy (and non-weedy) relatives.

  Other studies show that the release of herbicide-resistant oilseed rape can lead to spontaneous hybridisation between the crop and its weedy relatives. Research at INRA in France demonstrates that hybridisation can occur in the field between oilseed rape and wild radish (Raphanus raphanistrum). The progeny of the crop/weed hybrid exhibited characteristics of both parents (Darmency et al 1995).

  Other studies in France have shown that hybridisation occurs between oilseed rape and hoary mustard (Hirschfeldia incana). It was found that, under competitive conditions, these hybrid plants do better than the hoary mustard (Lefol et al 1995). Danish researchers also observed spontaneous hybridisation between oilseed rape and another weedy relative (Brassica campestris) under field conditions. The hybrid plants were highly fertile and carried a transgene from the oilseed rape (Mikkelsen et al 1996).

  Another recent French study on the gene flow from GE oilseed rape to wild radish (Raphanus raphanistrum), which was performed under field conditions over four generations, has shown that under natural conditions an intergeneric (between different species) gene flow might mainly occur, although slowly, by transgene introgression within the genome of the weed (Chèvre et al 1997).

  In Germany, the Robert Koch Institute, the competent authority for authorising the marketing of glufosinate resistant oilseed rape, states that "the introgression of genes from oilseed rape into related species such as Brassica campestris is possible. Hybridisation of different oilseed rape lines and thus the transfer of herbicide tolerance from the genetically engineered oilseed rape line to other oilseed rape varieties is also possible." (Robert-Koch-Institute 1996)

  Once transfer occurs an introduced gene may become a permanent feature of the genetic make-up of the plant, with unpredictable effects.

3.1.2 GE oilseed rape becoming established in ecosystems

  Oilseed rape (Brassica napus) has escaped cultivation to become widespread in many parts in Europe (Sukopp et al 1993). Adolphi (1995) reports on a frequent incidence of the wild growth of Brassica napus (in Germany). Unharvested and incidentally spilled seed can give rise to huge populations of oilseed rape. In growing amongst subsequent crops in rotation, at the edges of fields or on roadside verges, it is likely to escape cultivation and become established in ecosystems in many parts in Europe. The impact this will have on the environment has no precedent and is unknown.

  Once a crop escapes cultivation, it may become a permanent plant in the non-agricultural environment, with totally unpredictable effects.

3.1.3 Conclusion

  Current scientific studies and knowledge demonstrate that GE oilseed rape, when commercially released in Europe, may inevitably transfer genes to other oilseed rape and wild related species. These hybrids and the GE oilseed rape itself may become a permanent feature of ecosystems and fields. Their overall effects are unpredictable, and once these species are introduced it may take tens or even hundreds of years to recognise their effects.

  EU Directive 90/220, under which the authorisation for GE rape was granted, requires that adverse effects on the environment must be prevented. The commercial growing of GE oilseed rape bears the potential for serious environmental harm. Europe is the centre of origin of oilseed rape and gene transfer from GE rape to wild species is very likely. This means the authorisation allowing large-scale release of GE oilseed rape in Europe should be withdrawn immediately. Europe should base its decision-making on the precautionary principle.