How Scientists Test for Genetically Modified Wheat


The European Union and Korea have said they will test U.S. shipments of wheat for genetic modification. That's after last week's report that an unapproved strain of genetically modified wheat developed by Monsanto was found on an Oregon farm.

There currently isn't a verified commercially available test that can identify GM wheat, in part because the U.S. never approved GM wheat for planting.

Scientists use a method called the polymerase chain reaction- the same basic method that's allowed sequencing of the human genome and DNA forensics.

Bob Zemetra is a wheat breeder at Oregon State University. He says, "It's a very sensitive test. If the gene is there you can develop a program to detect it."

Zemetra says Monsanto's GM wheat has a telltale genetic sequence. It has three signature elements:

  • In the front there's a "start" sequence, taken from the cauliflower mosaic virus, called a promoter. That promoter is not found in normal wheat.
  • In the middle, there's a gene called CP4-epsps, which makes plants resistant to the herbicide Roundup.
  • After the CP4 gene, there's a "stop" sequence, called a NOS terminator. Like the promoter in the front, this terminator isn't found in other wheat plants.

Zemetra says a version of the polymerase chain reaction test is already used to monitor shipments of soy and corn and could be adapted to detect GM material in wheat shipments.

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