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A University of Arkansas researcher and her colleagues are developing a way
to examine how the genomes rearrange themselves during hybridization to
better pinpoint how genetically modified organisms may behave when they
cross with naturally occurring plants, February 2007.

Cindy Sagers, associate professor of biological sciences in the J. William
Fulbright College of Arts and Sciences; Chris Pires, assistant professor of
biological sciences at the University of Missouri, Columbia; and C. Neal
Stewart Jr., professor of plant sciences at the University of Tennessee are
examining chromosomes using specific dyes to look at how a particular
trait ? say herbicide resistance ? passes from one type of plant to another.

?Transgenic plants that escape into nature could become a very serious
problem,? Sagers said. Some types of plants, such as canola, creeping
bentgrass and rice, have mobile pollen that can cross-pollinate with
relatives and related weeds, which in turn can take on the genetically
modified trait. This could translate into herbicide-resistant weeds that can
wipe out crop fields, or non-modified crops contaminated with modified
genes ? both scenarios that have happened.

Sagers and Pires have applied for a Biotechnology Risk Assessment Grant from
the United States Department of Agriculture to examine how the genome
rearranges itself when genetically modified organisms and wild plants
hybridize. They will use fluorescent dyes to ?paint? specific chromosomes
and track their migration within particular hybrids. This will allow the
researchers to determine what specific pairings of populations create viable
hybrids with genetically modified components.

The scientists will use a relative of Arabidopsis for their research. Known
as ?the lab rat of the plant world,? the genetic sequence of Arabidopsis is
well documented, allowing the researchers to develop detailed examinations
of changes to the chromosomes in the canola crop genome.

By examining the issue of gene transfer at the chromosomal level, the
researchers will be able to determine how novel genes transfer from a
genetically modified crop into a weed or natural crop. This knowledge will
help scientists working with genetically modified crops to better control
and regulate the reproduction of desirable genes in the appropriate plants.

Sagers spent a year on a fellowship at an Environmental Protection Agency
laboratory in Corvallis, Ore., studying the potential cross-pollination of
herbicide resistant genes in canola. Canola makes a good experimental model
because of its short life cycle, its reproduction from seeds and its ability
to hybridize with close relatives.

They measured and weighed the parent and hybrid plants to see which ones
fared better in highly competitive environments under selection by insect
pests. The hybrids grew to be almost 15-fold larger than the parent plants.

?We know that there is hybrid vigor in the system,? Sagers said. ?We also
know that these hybrids can persist in the wild.?

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