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How rabbit genes could turn ordinary houseplants into pollution-eating machines

Tests show that genetically modified ivy can help eliminate toxins that build up in indoor air.
Image: The team behind the modified houseplants: Ryan Routsong, Long Zhang and Stuart Strand.
The team behind the modified houseplants: Ryan Routsong, Long Zhang and Stuart Strand.Mark Stone/University of Washington

By sucking carbon dioxide from the air while pumping out oxygen, green plants already do their fair share to fight air pollution. But scientists are prodding them to do even more: New research shows that simple tweaks of their DNA can give plants the ability to degrade a range of air pollutants — especially the ones that accumulate indoors, where Americans typically spend 90 percent of their time.

"Plants are very good at taking up chemicals from the air,” said Stuart Strand, an environmental engineer at the University of Washington in Seattle and a leader in efforts to develop pollution-eating plants. “They evolved to do it. So we're just taking advantage of that."

Strand's team wanted to see if a popular houseplant could be made to break down volatile organic compounds (VOCs); the toxic substances, given off by paints, solvents, air fresheners, cleaning supplies and other household items, have been linked to cancer, diabetes, respiratory problems and other ills. So the scientists inserted a synthetic version of a rabbit gene into Devil's Ivy (pothos ivy).

Their research showed that the gene caused the plant to make a toxin-neutralizing enzyme — and tests showed that the modified plant was able to suck up two common VOCs, chloroform and benzene, and transform them into harmless molecules that the plant might even be able to use for its own growth.

The researchers put both types of plants in glass tubes and then added either benzene or chloroform gas into each tube. Over 11 days, the team tracked how the concentration of each pollutant changed in each tube.Mark Stone/University of Washington

Of course, sticking one supercharged ivy plant in the corner is unlikely to eliminate indoor air pollution. The key is to bring as much air into direct contact with the plant. To do that, Strand's team is developing a sort of miniature greenhouse that contains multiple modified ivy plants and electric fans that direct room air over them.

Preliminary research shows that such a device, which would be roughly the size of a double-hung window, can remove gaseous toxins about as effectively as indoor air purifiers eliminate pollen and other particulate matter.

For plants in the home to be able to effectively remove hazardous molecules from the air, they would also need to be inside an enclosure with something to move air past their leaves, like a fan.Mark Stone/University of Washington

Future work will determine if the ivy can be modified to remove other VOCs. Strand’s team is working to add a gene from Brevibacillus brevis, a bacterium known for its ability to degrade formaldehyde, perhaps the most notorious of all indoor air pollutants.

"If we choose wisely, we might be able to come up with plants that detoxify many other pollutants in the environment," Strand said. "The use of genetically modified plants in this way is really only limited by our imagination."

Wariness over modified organisms

Illimar Altosaar, a biochemist at the University of Ottawa, praises the work being done by Strand’s team. "People still get diabetes," he said. "They still get cancer. And apparently our houses are full of formaldehyde. They are trying to make our environment better. It's very hopeful."

Lee Newman, a chemical ecologist at the State University of New York's College of Environmental Science and Forestry in Syracuse, also voices support for Strand’s work — with a caveat. "Developing ways to use nature to heal nature — that is absolutely fantastic," she said. "Whether or not the public will accept genetically engineered houseplants, however, is anyone's guess."

Many consumers strongly oppose genetically modified organisms (GMOs), at least when it comes to food. According to a poll conducted last year by the Pew Research Center, about half of Americans believe foods with genetically modified ingredients pose a health risk.

It's unclear how such opinions will translate to an inedible plant. Strand himself recognizes that the release of modified plants like his ivy could pose environmental risks. If a genetically modified plant released into the wild were to exhibit greater resistance than its wild counterpart to extreme weather or herbicides, for example, it might grow out of control. Given such concerns, his team is conducting a series of tests to determine if the plant poses any threats.

Bringing modified plants to market

If the tests allay concerns, Strand said the next step will be to get approval to sell the plant in the U.S. He anticipates the plant could be on the market within two years — and perhaps sooner in Canada. The Canadian government has approved the sale of the modified ivy, as Canada’s cold environment presumably wouldn’t allow the plant to survive more than a single growing season. Strand said he is now negotiating with companies there on commercializing the sale of the plant.

"There are no devices on the market for removing these compounds from home air," Strand said. "We think the best way to do this is with genetically modified plants."

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