Next, they used five different tests to confirm that the microbes really are fixing nitrogen, that the nitrogen moves into the corn, and that the corn gets a lot of its nitrogen—anywhere from 30 to 80 percent—in this way. All five techniques have their own shortcomings, but together “they all pointed to the same conclusion,” Bennett says. “We’ve been working on this for 10 years and we have a high degree of confidence that the results we report are correct.”
Others agree: “It was a very ambitious study that was really well done, and the results should be believed,” says Michael Kantar, a botanist at the University of Hawai’i at Mānoa. Yoder points out that the team hasn’t identified the specific nitrogen-fixing microbes, but beyond that, “I think it’s pretty convincing,” he told me. “Aerial-root mucilage that hosts nitrogen-fixing microbes is, quite honestly, a thing I’d have called a little far-fetched if I saw it on an episode of Star Trek,” he added on Twitter.
Scientists have spent years trying to create nitrogen-fixing cereal crops through genetic engineering, with little progress to show for it. But since we now know that at least one type of corn can fix nitrogen naturally, the ability could potentially be moved into conventional varieties through classical crossbreeding, mucus transplants, or both. These methods might make the final produce more publicly acceptable than a genetically edited crop.
For now, Bennett and his colleagues want to identify the genes that allow the Sierra Mixe corn to produce its mucus-coated aerial roots, and attract the right bacteria. They also want to take a closer look at the microbes themselves. “We’ve isolated thousands, but of those, we don’t know if there are two species that are really important or a hundred,” Bennett says.
And Shapiro, with the blessing of the Sierra Mixe community, is trying to find a company to take charge of commercialization. “It probably won’t be Mars Inc., ’cause we’re not a maize company,” he says, “but I’m trying to find the right partner.”
Kantar cautions that it’s too early to say if there are any big implications for food security, because the team hasn’t shown that the resulting corn can fix enough nitrogen to grow at commercially useful scales. It’s also unclear if the genes behind the ability come with any drawbacks. But “if these questions can be resolved, this may provide a way to significantly reduce fertilizer use worldwide, which would have hugely beneficial environmental effects,” he says.
Kristin Mercer from Ohio State University is similarly cautious. ‘This corn has been likely doing a very good job ensuring some level of food security for families in the region for a long time,” she says. “If one were to think about capturing that beneficial diversity and distributing it more widely, a number of potential issues arise.” Are there intellectual property issues around dispersing the genetic variation underlying this trait into public or private breeding programs? Would it be a good approach to create varieties of nitrogen-fixing corn for other areas where poor farmers live and asking them to buy those varieties?
“It is easy to jump from describing the amazing biology of these genetic resources stewarded by farmers in the region for millennia to trying to solve the world’s massive, intractable problems—but that is stickier than it may seem,” Mercer adds.