Genetically modified houseplant cleans indoor air

Researchers genetically modified a common houseplant, pothos ivy, to remove chloroform and benzene from the air around it.Mark Stone/University of Washington

The air in your home can affect your family’s health. Some airborne chemicals called volatile organic compounds, or VOCs, have been linked to cancer. VOCs can be released from common household products, furniture, and even cooking. The VOCs with the highest known cancer risk are formaldehyde, benzene, and chloroform.

Indoor plants can be used to help purify indoor air. Studies have suggested that common houseplants can remove VOCs from the air. However, there is disagreement about their effectiveness, and too many plants would be needed to clean the air of a typical room. To enhance their ability to remove VOCs, plants, including trees, have been genetically modified to produce cytochrome P450 2E1 (2E1), a key enzyme in mammals that helps clear toxins from the body. It normally helps break down toxins in the liver.

To test whether this gene could be used in indoor houseplants to more effectively purify indoor air for VOCs, a team led by Dr. Stuart E. Strand at the University of Washington genetically modified the common houseplant pothos ivy (Epipremnum aureum) to produce 2E1. The research was supported in part by NIH’s National Institute of Environmental Health Sciences (NIEHS). Results were published online on December 19, 2018, in Environmental Science & Technology.

The researchers spent years injecting a synthetic version of the gene for 2E1 into pothos ivy plants and cultivating new plant lines from those that incorporated the gene. They molecularly confirmed which plant lines contained the added gene.

The team next tested whether these genetically modified plants could remove two VOCs, benzene and chloroform. They placed modified plants and unmodified (wild-type) plants in glass containers that were filled with one of these chemicals for eleven days.

They found that the genetically modified plants cleared out 4.7 times more benzene than the wild-type plants. The genetically modified plants also decreased the concentration of chloroform by 82% during the first 3 days and almost completely after 6 days. In contrast, the wild-type plants did not clear any chloroform from the air.

“These are all stable compounds, so it’s really hard to get rid of them,” Strand says. “Without proteins to break down these molecules, we’d have to use high-energy processes to do it. It’s so much simpler and more sustainable to put these proteins all together in a houseplant.”

Strand says that 2E1 can be beneficial for the plant, too, as it turns chloroform into carbon dioxide and chloride ions, and benzene into a chemical called phenol. “Plants use carbon dioxide to make their food, and they use phenol to help make components of their cell walls,” he explains.

The team is now testing ways to combine this gene modification with other modifications that can clear out formaldehyde. Pothos ivy doesn’t normally flower, so these genetic modifications won’t be able to spread via pollen.

—Tianna Hicklin, Ph.D.