Minneapolis, Minnesota
May 5, 2009
University of Minnesota and Massachusetts
General Hospital researchers used a new method of genetic
modification to alter a single gene in tobacco plants.
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University and Massachusetts General Hospital
researchers used a new method of genetic modification to
alter a single gene in tobacco plants. |
The controversy surrounding
genetic modification of plants stems partly from the way it's
done: Genes are introduced in scattergun fashion, with little
control over where they integrate into the genome and what
effects that may have.
But a new, precise method promises to restore much of that lost
control. Developed by
University of
Minnesota and
Massachusetts General
Hospital researchers, it
uses an enzyme that reads DNA like Braille and makes pinpoint
changes in the gene targeted for modification.
In a paper published April 29 online in
Nature, a team led by
University of Minnesota researcher
Daniel Voytas describes how
they used the method to engineer tobacco plants for resistance
to herbicide. Only one gene was changed, and no genes were added
to the plant's chromosomes.
The method has potential for changing the way researchers
approach a host of tasks, such as making crops more nutritious
or resistant to adverse conditions, coaxing algae to produce
more biofuel, or even curing diseases in humans and other
animals.
"My colleagues and I demonstrated the first use of the
technology in plants, and we and others have shown it to work in
human cell lines and other animal models, such as fruit flies
and roundworms," says Voytas, a professor of genetics, cell
biology and development and director of the University's new
Center for Genome Engineering.
"The method offers enormous potential for gene therapy, and its
advantage is its precision."
The enzymes at the heart of the technology are known as zinc
finger nucleases, or ZFNs. In doing their job, ZFNs explore the
DNA in a cell nucleus, probing with extensions—"zinc
fingers"—until they find the particular DNA sequences they have
been designed to ferret out. They then chop those sequences out
of the chromosome, replacing them with new sequences—provided by
the researchers—that confer herbicide resistance or other
traits.
In the case of the tobacco plant, "the modified gene is a widely
used target for herbicides," says Voytas. When functioning
normally, the gene instructs the cell to make a protein that's
crucial for life but that can be disabled if a herbicide
molecule attaches to it.
But the modified gene instructs the cell to make a slightly
altered version of the protein, one that can still perform its
cellular duty but offers no foothold for a herbicide. And so the
plant becomes herbicide-resistant.
Voytas is now testing the method in rice, the world's most
important crop; a member of the mustard family called
Arabidopsis, a widely studied model plant; and algae with the
potential to produce biofuel. If successful, ZFNs could become
the tool of choice for getting more bang for the agricultural
buck.
Or, as Voytas puts it, "The technology is ready for prime time."
By Deane Morrison |
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