Gene escape from GE insect resistant eggplants could create aggressive weeds in South and South-East Asia
17 February 2011
© VJ Villafranca / Greenpeace
We know that growing genetically engineered (GE) crops risks harm to the environment and our health, but exactly what are the dangers and how might they occur?
One danger often cited is that gene escape to wild populations could cause these populations to become more vigorous weeds. This could happen if certain GE crops (e.g. those insect-resistance genes) are grown in places where local varieties (landraces) or wild (and weedy) relatives occur, for example in their centres of diversity. This danger might become a reality if proposals to grow GE insect-resistant (Bt) brinjal (also called eggplant or talong) in countries such as India and the Philippines go ahead.
All crop plants originally derive, or are “domesticated”, from wild plants in their centre of origin. In centres of diversity, the greatest diversity of cultivated types or landraces occurs. These centres of origin and diversity are the sorts of places where you’d expect to find wild relatives and landraces. Centres of diversity are the basis not only for food security, but also for cultural traditions - they are very special. But these centres of diversity are vulnerable to GE contamination as GE genes can escape to wild and local populations. Once in these local populations, the GE gene may persist, and have consequences for further GE contamination, ecological effects and food security.
The centre of origin for brinjal is not clear. However, the centre of diversity of brinjal is thought to spread through the whole of South-East Asia, from India to China and Indonesia (including the Philippines). This area includes countries where the cultivation of GE Bt brinjal is being considered, such as India and the Philippines. Growing GE Bt brinjal in its centre of diversity spells bad news.
It is generally agreed that GE contamination is possible, even probable, in a centre of diversity. Conventional oilseed rape, maize, sunflowers, potato, sorghum, and many other crops can crossbreed with relatives that grow in their centre of diversity. It would seem likely, therefore, that GE crops would crossbreed with their relatives too, but would also pass on the GE gene to these relatives. Concerns regarding GE contamination of landraces are at the centre of the Greenpeace’s campaign against GE maize in Mexico, because it is both a centre of origin and diversity for maize, and a staple crop for most Mexicans
GE contamination is inevitable if GE crops are grown outdoors, even as field trials. We know that GE contamination of conventional, or non-GE, crops can happen as there are plenty of examples. There are also several examples of GE contamination from experimental field trials, where the GE crop has not been approved for growth or human consumption, yet it ends up in our food.
The additional risks associated with GE contamination from GE Bt brinjal within its centre of diversity have largely been overlooked in the risk assessments for GE Bt brinjal, partly because little recent information exists. An independent study, commissioned by Greenpeace, finds that brinjal relatives do occur in the regions where the cultivation of GE Bt brinjal is proposed, and that GE Bt brinjal may mate with these relatives to spread the GE Bt gene. The exact number of species that can breed with cultivated brinjal is not precisely known, but the report shows there are at least 10 closely related species found in South and South-East Asia that cultivated brinjal can mate with.
This new study has important implications. Concerns with crossbreeding and spreading of the GE gene through landrace populations and wild and weedy relatives include: food safety concerns; ecological effects; lack of GE-free choice; loss of biological and cultural heritage and undermining of food security. One major fear is the possibility that the newly introduced GE gene will confer a selective advantage that might enable the plant to out-compete and overrun other natural vegetation. Insect-resistance is an example of such as trait, and has been engineered into GE brinjal as a “Bt” gene. Hence, should these wild or weedy relatives of brinjal acquire the GE Bt gene; it could result in brinjal becoming an aggressive and problematic weed that might wreak havoc in both agriculture and natural habitats.
GE crops should not be cultivated outdoors anywhere in the world, but if they are grown in their centres of diversity, the risks of outcrossing to relatives and spreading through populations of landraces, wild and weedy relatives and landraces are very real. The consequences of widespread contamination are potentially serious. Especially, as in the case of GE Bt brinjal, the insect-resistant GE genes are advantageous to a plant, and this risks creating problem weeds.
Greenpeace urges governments to employ the precautionary principle and not permit any authorisation of the outdoor cultivation of GE Btbrinjal, including field trials.
Summary of the study
Dr. Janet Cotter, Greenpeace International Science Unit