When a scorching heat wave struck Illinois in June 2022, crop physiologist Katherine Meacham-Hensold hoped her team’s new bioengineered potato variety would survive it—but she was astonished by just how well it thrived. The plant yielded 30 percent more of its large red tubers than a normal, unengineered plant in the same conditions, according to a recent study in Global Change Biology.
“This study is particularly noteworthy because it shows real benefits in a field setting with a staple crop,” says biochemist Edward Smith of the University of Oxford, who was not involved in the research. “There’s no reason this technology couldn’t be applied to more crops.”
To engineer the potato, Meacham-Hensold and her colleagues at the University of Illinois Urbana-Champaign focused on an inconvenient heat-triggered process in most plants called photorespiration, in which a key photosynthesis enzyme known as RuBisCO gets sidetracked and begins making a toxic by-product. RuBisCO molecules need to bind to carbon dioxide to carry out photosynthesis, but about a quarter of the time they grab oxygen instead—and this erroneous process happens more often at high temperatures. This inefficiency can decrease crop yields by as much as 50 percent.
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In the new engineered potatoes, a gene inserted into the plant cell’s nucleus produced a protein that traveled into the chloroplast, the cell organelle used in photosynthesis. There it broke down the toxic by-product, so the chloroplast didn’t need to send it out to other organelles. This saved energy, similar to how eating local food saves the energy of trucking it across the country.
During the engineered potatoes’ 2022 growing season in the Illinois test field, an extreme heat wave brought four consecutive days with temperatures higher than 95 degrees Fahrenheit. But the new potato’s genetic change which can be passed on to the next generation—boosted yield by almost a third. “We were really shocked,” Meacham-Hensold says. The photosynthesis process is a promising target for agricultural engineering, she adds, because it can increase crop yield without the need for extra land use and fertilizer. The results are exciting, Smith says, although he’d like to see data from future growing seasons.
The new technique could help crops adapt to climate change. Similar strategies have been used previously in rice, but this study is the first to show that it doesn’t cause a decrease in a food crop’s nutritional quality, Meacham Hensold says: the team froze and ground up the tubers to measure their starch, fiber, sugars, protein, calcium, potassium, iron, and vitamins B6 and C.
Next the researchers are working on soybeans and cowpeas; the latter is “a hugely important food-security crop in African countries,” Meacham-Hensold says. A high-yield soybean variety with the same genetic change will hit the field this year.
