Herbicide-Tolerant Crops without the Foreign Genes

Using a tailor-made enzyme, scientists at the University of Minnesota and Massachusetts General Hospital developed an herbicide-tolerant tobacco plant without significant changes to its DNA. "It's still a GMO but the modification was subtle," says Daniel Voytas lead author of the paper published online by Nature. "We made a slight change in the sequence of the plant's own DNA rather than adding foreign DNA." The new approach has the potential to develop improved crop varieties while minimizing concerns about genetically modified organisms.

Voytas and colleagues used a zinc finger nuclease (ZFN) to target tobacco acetolactate synthase (ALS) genes. Mutations in the ALS genes have been shown to confer resistance to imidazolinone and sulphonylurea herbicides. The scientists observed high frequency of gene targeting, with more than 40 percent of the recombinant plants having modifications in the ALS gene.

ZFNs are synthetic proteins that bind to specific DNA sequences and introduce modifications at or near the binding site by inducing double strand breaks. ZFNs have been used to manipulate the genomes of several organisms, from tobacco to zebrafish and even mammalian cells.

For more information, read http://www1.umn.edu/news/news-releases/2009/UR_CONTENT_107428.html The paper published by Nature is available at http://dx.doi.org/10.1038/nature07845