Environmental risks of GM crops
Environmental risks from genetically modified (GM) crops is a hotly debated topic in New Zealand and throughout the world. In June 2002, Manaaki Whenua initiated the Environmental Biosafety Project to assess the potential for environmental impacts in New Zealand. The project’s aim is to provide data and guidelines for decisions on containing, releasing and monitoring GM crops. We assembled a multi-disciplinary team that includes experts in population genetics, pollination biology, ecology, evolution, biosystematics and geographic information systems (GIS).
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| Peter Heenan examining a wild Brassica population. Image - Richard Fitzjohn |
Hybridisation1 between GM crops and native species is of particular concern given the unique nature of New Zealand’s native flora. We reviewed experimental evidence based on hand pollination for the potential of 148 major crops to hybridise with closely related native and exotic species in New Zealand. The review indicated that 16 crops have close relatives in the native flora and one of these, native celery, is capable of hybridisation. Two crops showed evidence that they are not able to hybridise with native species but no information was found for 14 other crops with native relatives. Our review of the exotic naturalised flora showed that 66 crops can hybridise successfully with at least one naturalised wild relative present in New Zealand; 25 crops cannot interbreed with any of their wild relatives; and an additional 25 crops have no wild relatives in New Zealand. Information is lacking for 20 crops.
We also developed the New Zealand Biosafety Database to record and track information so that it can be used in a transparent manner. We used the database to make a detailed assessment of experimental hybridisation in the Brassica species complex, which contains eight crops (including turnips and cabbage), and over 20 wild relatives in New Zealand. We identified species combinations that were reproductively compatible, incompatible, or for which information was lacking. We are currently working on assessments for other crops. We are also using the database to manage information on pollination, and have published a review of pollination in New Zealand.
Hybridisation between crops and wild relatives is most likely where both are in close proximity. However, local information on the distribution of wild relatives is scarce. Our roadside survey of 50 randomly distributed plots found 107 wild populations of Brassica outside cultivation in the Canterbury region. Several cases of natural hybridisation were found, including one between different varieties of turnip, and one interspecific hybrid between turnip and rape. The distances from the Brassica populations to highways, seed production and storage areas (and other similar factors relevant to distribution) are being incorporated into a model that aims to predict the distribution of wild populations at the landscape scale.
Another debated issue is whether it is possible to keep conventional, organic, and GM crops isolated from each other to preserve consumer choice nationally and in the export market. We have initiated research on the distances over which crop plants can cross-pollinate (i.e. gene flow distances) under New Zealand weather conditions. We are using maize, which is wind-pollinated, as a case study.
The Environmental Biosafety Project is providing scientifically sound data to support informed debate about the benefits and risks of GM crops. Manaaki Whenua has expertise in ecology and evolution, both of which are fundamental to developing robust assessments of environmental risks of GM crops.
1 Hybridisation is the interbreeding of two different species or varieties of plants or other living organisms.
‘He take whakahirahira tēnei te whakatakoto kaupapa taiao e tika ana mo te pāmu kai taketake, kia kore hoki e tūkinotia te taiao. Na te mea hoki ko tātou te iwi Māori ngā kaitiaki o te taiao.’
It is important to have scientifically-robust information to support prudent decision-making to minimise environmental risks posed by transgenic crops. As kaitiaki, this type of research is therefore vital for Māori .
Shaun Ogilvie Lecturer, Lincoln University, Canterbury.
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Linda Newstrom
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On our website |
Gene flow assessment project - published papers and reports |
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Funding |
| FRST |