Seeds are more likely than pollen to spread genes from genetically-modified sugar beet into wild relatives, researchers have warned.
Previously, concern about the leakage of genes from GM crops into the environment has focused on pollen, which can blow for long distances on the wind. But new research in France reveals that the transport of seeds may present a greater risk.
Jean-Fran莽ois Arnaud, head of the research team at Lille University, says: 鈥淎ccidental transport of seeds within soils carried on motor vehicles, or by other normal agricultural activities provide the best explanation.鈥�
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Arnaud鈥檚 team used molecular markers to track different types of sugar beet, including the weedy hybrids of commercial and wild sugar beet that commonly form in fields.
The team found that the weedy hybrids, which produce more seeds that the commercial sugar beets, had somehow migrated 1500 metres from the fields and were mingling with wild sea beet. The far-flung hybrids must have come from seed because they had maternal genes, rather than the paternal ones carried by pollen.
Dropped dirt
Arnaud thinks that soil transported from beet growing areas to assist with dyke reconstruction might have carried the seeds, or that seeds might have been dropped in dirt from lorries transporting harvested beet to factories.
No GM varieties were Arnaud鈥檚 research, but the principle would be the same. The implication is that the inadvertent transport of seeds might have been overlooked when assessing the risks posed by GM sugar beet.
鈥淥ur result was unexpected,鈥� the team write in Proceedings of the Royal Society B, 鈥渟ince most studies involving the assessment of transgene escape generally focus only on pollen dispersal.鈥�
鈥業nevitable consequence鈥�
Arnaud warns that care should therefore be taken in choosing where to grow sugar beet. Furthermore, farmers growing GM sugar beet might need to dig up the weedy hybrids in their fields to stop them producing seeds that could then be dispersed.
Jeremy Sweet of NIAB, a crop research company in Cambridge, UK, goes further: 鈥淭he research means that if you put any gene into sugar beet, it would get into wild beet 鈥� it鈥檚 inevitable. But it is taken into account when risk assessments are conducted on GM beet.鈥�
He says that the environmental impact on the wild sea beet would therefore depend on whether the gene significantly alters the behaviour or ecology of that plant.
Journal reference: Proceedings of the Royal Society B (DOI: 10.1098/rspb.2003.2407)
