Isolation distance for genetically modified plants
Encyclopedia
Isolation distances are used in regions where genetically modified
(GM) and conventional or organic crops are grown in co-existence
. When different cropping systems are grown in proximity to each other, the "isolation distance" between fields refers to the area separating them, on which genetically modified pollen
can settle without fertilising non-GM crops.
).
or "buffer zones".
. Further results from various projects have been compiled by GMO-Safety.eu.
Genetic engineering
Genetic engineering, also called genetic modification, is the direct human manipulation of an organism's genome using modern DNA technology. It involves the introduction of foreign DNA or synthetic genes into the organism of interest...
(GM) and conventional or organic crops are grown in co-existence
Co-existence of genetically modified and conventional crops and derived food and feed
In the context of agriculture and food and feed production, co-existence means using cropping systems with and without genetically modified organisms in parallel. For co-existence to be assured, the separation and the identity of the respective food and feed products must be maintained at all...
. When different cropping systems are grown in proximity to each other, the "isolation distance" between fields refers to the area separating them, on which genetically modified pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
can settle without fertilising non-GM crops.
Goal of isolation distances
The goal of isolation distances is to minimise out-crossing of GM plants. If large amounts of GM pollen fertilise crops in a non-GM field, that harvest may no longer be declared "GM-free", and will require appropriate labelling if its GM content exceeds a certain limit (e.g. 0.9 percent in the European UnionEuropean Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
).
Design of isolation distances
Isolation distances are mostly empty spaces. They may be roads, uncultivated fields, or anything that separates two fields without actively hindering the drift of pollen. Separation methods between GM and non-GM fields which actively catch pollen are called "pollen barriers"Pollen barrier
A physical obstacle that hinders the movement of pollen from a field of genetically modified crops to neighbouring non-GM crops is called a pollen barrier. Such barriers are erected with the aim of reducing the out-crossing of GM plants...
or "buffer zones".
Factors influencing isolation distances
Many factors influence the width required for isolation. A major criterion is the crop species, since isolation distances often must be calculated according to pollen weight. Other influential criteria include the size and shape of fields, GM-contamination tolerance levels and, especially, local wind direction and weather conditions.Isolation distances for maize
Maize is probably the best-studied crop in terms of isolation distances. Yet, recommendations for isolation distances have varied significantly. Under average conditions, the isolation distance may be 25 metres. However, in regions with small non-GM fields (< 1 hectare), or with crops being grown primarily for seed production, the isolation distance may be more than 100 metres.Research on isolation distances
Among dozens of individual research projects, there are two extensive programmes investigating isolation distances for relevant crop species: SIGMEA and Co-ExtraCo-Extra
Co-Extra is an EU-funded research programme on co-existence and traceability of genetically modified crops and their edible derivatives. It has been granted €13.5 million under the Sixth Framework Programme of the European Union, and is conducted by more than 200 scientists in 52 organisations in...
. Further results from various projects have been compiled by GMO-Safety.eu.