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A bruised potato. The discoloration that occurs after tissue damage is largely caused by the activity of the enzyme polyphenoloxidase (PPO). In the Calyxt PPO_KO potato variety (one of the) genes coding for the PPO enzyme is knocked out, making the variety less susceptible to (the visible effects of) bruising. (Photo: Courtesy of AHDB Potatoes/Sutton Bridge CSR)

USDA clears new GMO potato variety

A new potato variety that’s genetically modified to withstand bruising has been cleared for commercialization without undergoing USDA’s deregulatory process for biotech crops.

The agency has advised the potato’s developer, Calyxt, the cultivar is not a “regulated article” under federal law because it doesn’t contain genes from plant pests.

Because most commercial biotech crops incorporate genes from plant pests, they were subject to environmental analysis and a risk assessment from USDA before they were deregulated.

In the case of Calyxt’s “PPO_KO” potato, the variety was created through the “knockout” of an unwanted gene that causes bruising without leaving plant pest genes in the crop.

The cultivar will reduce browning in fresh potatoes as well as bruising “to minimize crop rejection and waste in processing lines,” said Federico Tripodi, Calyxt’s CEO. Up to five per cent of fries and chips are rejected because of discoloration, he said.

With the USDA’s recent approval, the company plans to work with “third party researchers” to plant the variety in U.S. fields, he said.

The PPO_KO variety is the second genetically modified potato developed by Calyxt that USDA has cleared for commercialization without undergoing the deregulatory process. An earlier variety, which inactivates a gene associated with the cancer-causing compound acrylamide, was approved in 2014 and is currently in field trials.

The J.R. Simplot Co. has obtained USDA approval for potatoes with similar traits in recent years, but these were initially regulated as possible plant pests by the agency.

The Center for Food Safety, a prominent critic of genetically engineered crops, is skeptical of the PPO_KO potato’s benefits.

Calyxt has eliminated the gene responsible for producing the enzyme polyphenol oxidase, or PPO, which performs functions other than causing bruises, said Bill Freese, science policy analyst with the group.

For example, the enzyme is associated with greater pest and disease resistance, he said. “One question is, by knocking out these genes, are you making the plant weaker and more susceptible to disease?”

Such modification could also have other unforeseen consequences, he said. “You could be knocking out genes you didn’t intend to knock out.”

It’s possible potatoes lacking the PPO gene may harbor disease in fields abandoned due to low prices or crop damage, which should have been analyzed by USDA, said Freese.

“This is a plant pest risk. We’re not saying it is for certain, but they should be looking at it and they’re not,” he said.

Calyxt acknowledged that PPO is associated with disease resistance, but said the company has only eliminated one of at least six genes associated with the enzyme.

“Therefore, the other PPO genes will still be functional to help protect the potato plants from disease, insects and other stresses,” the company said in an email.

The company also said it has created multiple lines of the PPO_KO variety and will field test them to select those “with the best agronomic characteristics, including desired levels of disease resistance.”

Source: Capital Press


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