Wednesday, 2 April 2008, 01:40 CDT
Scientists discovered seeds from certain genetically modified crops can endure soil for at least 10 years in some cases.
A field planted with experimental oilseed rape a decade ago found transgenic specimens were still growing there despite intensive efforts over the years to remove the seeds, according to researchers in Sweden.
This is the first time a genetically modified crop has endured so long and critics say it shows that genetically modified organisms cannot be contained once released.
Tina D'Hertefeldt and a team of researchers from Lund University searched a small field that hosted the GM trial 10 years ago looking for "volunteers" - plants that have sprung up spontaneously from seed in the soil.
"We were surprised, very surprised," said D'Hertefeldt. "We knew that volunteers had been detected earlier, but we thought they'd all have gone by now."
The researchers presented their findings in the journal 'Biology Letters' and found that after the trial of herbicide-resistant GM rape, the Swedish Board of Agriculture covered the field with chemicals that should have killed all the remaining plants.
Inspectors searched specifically for two years to find and kill volunteer plants — more effort than would usually be deployed on a normal farmer's field.
However, 15 plants had sprung up 10 years later carrying the genes that scientists had originally inserted into their experimental rape variety to make them resistant to the herbicide glufosinate.
Researchers also noted non-GM varieties used in the 10-year-old study that had also survived.
"I wouldn't say that the transgenic varieties are able to survive better," said Dr D'Hertefeldt. "It's just that oilseed rape is a tough plant."
Jeremy Sweet, once the head of the UK's National Institute of Agricultural Botany and now an independent consultant on biotech crops, agreed.
"It's been known for some time that oilseed rape is a bit of a problem because of the survival of its seed," said Sweet.
Sweet said if farmers want to swap from growing GM rape to conventional varieties, they will have to wait a number of years.
Rapeseed is the fourth most commonly grown GM crop in the world, after soya beans, maize and cotton. It is often known by its Canadian name canola.
According to the International Service for the Acquisition of Agri-biotech Applications (ISAAA), an industry organization, more than one million square kilometers of land across the world are now dedicated to growing GM plants.
Europe accounts for only about 0.1% of that total—a single maize variety being the only transgenic food plant being grown.
The UK and many other European countries have not yet issued legislation on how fields of genetically modified crops could co-exist with others that farmers want to keep free of transgenic material.
The UK government published a consultation paper two years ago including proposals on issues such as minimum distances between fields growing biotech and conventional varieties, compensation, and labeling of GM foods. Wales, Scotland and Northern Ireland regulations are dealt with by the devolved administrations.
Some campaign groups say the proposals are insufficient, specifically on the grounds that farmers would not be liable for environmental impacts of the crops they grow.
Clare Oxborrow, GM campaigner with Friends of the Earth (FoE) UK, said the Swedish research strengthened their case.
"Despite the best efforts by the researchers to eliminate GM oilseed rape, it appears that once it is planted, it is virtually impossible to prevent GM contamination of future crops," said Oxborrow.
"The government must now tear up its weak proposals for the 'coexistence' of GM with organic and conventional crops, and put in place tough rules that protect GM-free food and farming."
According to D'Hertefeldt, the Lund research does not deal with the flow of genes into neighboring fields, or whether transgenes can transfer into wild plants growing nearby.
She believes legislators do need to take note of her findings.
"What we are saying is they also need to take into account the temporal aspect," she said.
"This study confirms that GM crops are difficult to confine," said Professor Mark Westoby, a plant ecologist from Macquarie University in Australia.
"We should assume that GM organisms cannot be confined, and ask instead what will become of them when they escape."
Genetically modified organisms are altered using a genetic engineering technique known as recombinant DNA technology. DNA molecules from different sources are combined in vitro into one molecule to create a new gene. This DNA is then transferred into an organism and causes the expression of modified or novel traits.