GM field trials 'underestimate potential for cross-pollination' - study

Field trials could be underestimating the potential for cross-pollination between genetically modified and conventional crops, according to new research by the University of Exeter. The research team recommends a new method for predicting the potential for cross-pollination, which takes account of wind speed and direction.

The findings are important in the context of biofuels, since interest in genetically altered energy crops is steadily growing (previous post, on transgenic switchgrass and on GM sugarcane). Some GM crops, like maize and canola are already being used for biofuels on a large scale. And even though such plants are currently not cultivated widely in the EU, pro-GM lobbies are more active than ever. The European Parliament recently voted in favor of national bans on GMOs, against the position taken by the EU Commission, which is in favor of the introduction of such crops in the Union (earlier post). What is more, GM energy crops could be introduced in the developing world first, where environmental and precautionary standards may be less strict. The new scientific findings may help craft more stringent field trial procedures.

The research [*abstract], funded by the Natural Environment Research Council (NERC) and published today in the journal Ecological Applications, used records of wind speed and direction from weather stations across Europe to predict the movement of pollen in the air. The findings show huge variation in the amount of cross-pollination between GM and non-GM crops of maize, oilseed rape, rice and sugar beet. Levels vary according to whether the GM field is upwind or downwind of the non-GM field given the direction of the prevailing wind over the flowering period of the crop.

Field trials are regularly carried out to measure the potential for cross-pollination between GM and conventional crops. Current guidelines for minimum field-to-field distances are based on the results from these trials. However, if the GM field in a trial is downwind of the non-GM field, the trial will underestimate the potential for cross-pollination:
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'We were struck by the strong influence of wind direction on the amount of cross-pollination', said Martin Hoyle of the University of Exeter. 'Wind speed and direction are important factors outside of our control that have not previously been used to inform guidelines on minimum field-to-field distances. Recommended minimum distances between GM and conventional crops may need to be increased based on our findings.'

Field trials are time-consuming and expensive, so measuring the potential for cross-pollination across the full range of weather conditions is not feasible. This research resulted in the development of a theoretical computer model to analyse the effects of wind on pollen travel. The model, together with measurements of cross-pollination and wind speed and direction from field trials, can be used to predict cross-pollination at other times and sites.

'If the production of GM crops becomes widespread in Europe, it is essential that measures are taken to minimise cross-pollination from GM to conventional non-GM crops,' said Hoyle. 'The recommended minimum distances between GM and conventional crops should be informed by weather data, which is possible using our model of pollen dispersal in the wind.'

More information:
Martin Hoyle,a and James E. Cresswella, "The effect of wind direction on cross-pollination in wind-pollinated GM crops" [*abstract], Ecological Applications: Vol. 17, No. 4, pp. 1234–1243.