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2-Plants: Concerns over GE wheat: Keeping genes in their place

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-------------------------------- GENET-news --------------------------------

TITLE:  Concerns over GE wheat: Keeping genes in their place
SOURCE: Idaho Farmer Stockman, USA, a Farm Progress publication
        edited and sent by Agnet, Canada
DATE:   October 20, 2000

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Concerns over GE wheat: Keeping genes in their  place

Researchers in Idaho and Oregon will use $900,000 over the next four years 
to develop ways to prevent the escape of genes from genetically modified 
wheat into the closely related weed, jointed goatgrass. Project leaders 
Robert Zemetra, a University of Idaho wheat breeder in Moscow, and Carol 
Mallory-Smith, Oregon State University weed scientist at Corvallis, found 
that wheat and jointed goatgrass could cross naturally and form partially 
fertile hybrids. They published their findings in the 1998 journal Weed 

While genetically modified wheat has yet to be approved for production in 
the United States, some fear that when it is, new genes could escape into 
the crop's wild relatives, creating super weeds. Zemetra says the research 
is geared to preclude the problem from arising in the first place. Jointed 
goatgrass, an introduced weed, is found in 48 states and is particularly 
troublesome for winter wheat growers, infesting 5 million acres planted to 
the grain and another 2.5 million fallow acres. The estimated loss to 
growers is $45 million a year from reduced production and grain value.

Idaho and Oregon are already part of an 11-state research program with 
Montana, Texas, Colorado, Kansas, Nebraska, Oklahoma, Wyoming, Utah and 
Washington to combat the weed. "Jointed goatgrass is a major problem for 
wheat farmers in the western United States," says Zemetra. "And part of the 
problem is because it is so closely related to wheat, it is difficult to 
control once it gets established in a field."

The difficulty results from a shared genome. Wheat has six sets of 
chromosomes, two from each of its ancestors. Jointed goatgrass has four 
sets of chromosomes, two of them from a parent species it shares with 
wheat. Their similarities mean herbicides that killing jointed goatgrass 
kills wheat, too. Cultivation and other strategies to kill the weed also 
kill the crop. The problem has increased interest in the development of 
herbicide resistant-wheat varieties through genetic engineering. That way, 
a herbicide could be sprayed on a wheat field, killing the weed and leaving 
the resistant wheat plants to grow without competition.

A problem that could occur with a genetically modified plant is a gene 
crossing from crops to weeds. "One of the ideas is, could gene placement 
minimize or prevent the movement of a transgenic gene from wheat into a 
weedy species?" says Zemetra. He notes that it may be possible to prevent 
the herbicide-resistance gene from leaping from wheat to weed by inserting 
it into the two wheat genomes not shared by goatgrass.

The research will test the mechanisms at work in gene transfers between 
wheat and jointed goatgrass. The team will also develop management 
strategies growers can use to minimize the chances of gene transfers from 
wheat to weed, says Zemetra. The research could also apply to other 
polyploid crops, those with multiple sets of chromosomes, like canola and 

"You could potentially extrapolate what we find out about the genome work 
from wheat to something like canola for determining how easy would a gene 
move and be retained in its weedy relatives," Zemetra says. Joining Zemetra 
and Mallory-Smith on the project, funded by the U.S. Department of 
Agriculture, will be UI weed scientist and extension specialist Don 
Morishita at Twin Falls and OSU crop scientist Oscar Riera-Lizarazu. 

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