Scientists have unveiled a new way of altering the genetic sequence of a crop to produce a desired trait without needing to introduce foreign genes.
The technique could be less controversial than conventional genetic modification because it does not involve transferring a gene from another species.
Scientists used a set of enzymes to "subtly change" a tobacco plant's DNA to make it herbicide resistant.
The enzymes — known as zinc finger nucleases — can be engineered in the lab to target specific genes, introducing changes known to cause the desired trait.
Until now there has been no efficient way of making such changes to plant genes.
Daniel Voytas, director of the US-based University of Minnesota Center for Genome Engineering and the lead author of the research says: "We changed a few letters in the genetic code of a native plant gene and made the plant resistant to herbicide. In most genetically modified crops, herbicide resistance is conferred by adding a foreign gene, usually from bacteria."
The researchers hope the technique will revolutionise how crops are genetically modified.
"We need to test this technology and compare it with traditional methods of gene transfer. I think ... precise DNA sequence modifications that do not introduce foreign DNA will be preferred over traditional approaches," Voytas told SciDev.Net.
Voytas says the technique requires only standard molecular biology laboratories and competence in introducing DNA into plants — resources that are available in many parts of the developing world. He also says capacity to do such work should be increased in developing countries.
Kamonji Wachiira, an environmental consultant based in Ottawa, Canada, says the technique sounds promising but seems to be largely untested.
There are also concerns about its effectiveness, and the usual biosafety issues associated with genetic modification, says Wachiira. He adds that the zinc finger nucleases could have unpredictable effects on several genes. "The new trait may well be accompanied by latent, recessive or unintended but risky traits."
The research was published in April in Nature.
Nature 459, 442 (2009)