Corn is a colossal grain in the global food and feed chain, with the U.S. producing roughly 30% of the world's supply , or nearly 278 million metric tons in the 2024-25 growing season alone. But its journey from wild grass to staple crop began in central Mexico with teosinte (from the Nahuatl word "teocintli," meaning "sacred corn"). Over thousands of years, domestication and selective breeding transformed teosinte into the corn we enjoy at backyard barbecues today.
Now, researchers are returning to this wild crop relative to investigate traits that may have inadvertently been left behind, traits that influence how roots interact with soil microbes and cycle nitrogen.
In a study published in Science Advances, researchers compared modern corn with maize lines integrated with specific, inherited traits from teosinte. They found that these traits create distinct microbial environments in the rhizosphere – the narrow zone of soil around their roots – subtly affecting nitrogen cycling under field conditions.
"The key here is we can use wild genetic variation in our crops to make our modern agricultural system more sustainable," said Alonso Favela, lead author on the study and a plant microbial ecologist in the University of Arizona School of Plant Sciences .
It's an increasingly popular way of thinking about sustainability in agricultural, focused on reconnecting modern crops with traits tied to their evolutionary history. Researchers are already looking at wild crop relatives for characteristics such as heat tolerance and pest resistance. Favela's research team focuses underground, to ancestral traits that may conduct nitrogen efficiency.
"If we can reintroduce these traits, modern maize becomes more sustainable, potentially making corn production cheaper via lower nitrogen inputs and keeping more of that nitrogen in the field as opposed to the surrounding environment," he said.
What's happening below the surface
Nitrogen is essential for crop growth, yet plants take up only about half of nitrogen fertilizer applied to fields. The remainder is often transformed by soil microbes into forms that escape into the environment, whether through gases released into the atmosphere, such as nitrous oxide, or in soluble forms that can leach into nearby streams or groundwater systems.
These microbial processes occur in the rhizosphere, where plants' roots and microbes closely interact. Understanding how plants influence, or in some ways conduct, this microbial orchestra has become an important focus in both soil science and agricultural research.
"The microbes I study are called nitrifiers. They're really, really weird microbes, and they metabolize nitrogen, much like we metabolize sugars," Favela said. "They love agricultural fields because that's a huge area where nitrogen is being actively enriched."
While in nature, plants have evolved to compete with these "nitrogen-metabolizing" microbes for available nitrogen, commodified corn has been bred within nitrogen abundance and has largely lost this competitive edge.
"Modern maize doesn't really manage its nitrogen because there's so much nitrogen around, but teosinte is really good at competing with these microbes," Favela said. "By reintroducing some of its characteristics, we alter the relationship with these nitrifying microbes, so instead of a large fraction of the applied nitrogen going to these microbes that don't contribute to yield – it's going to the plant and staying in the fields."
To understand how teosinte's inherited root traits influence soil microbial communities, the research team conducted field experiments at the University of Illinois Crop Sciences Research and Education Center in Urbana. There, model maize (known by growers as B73), teosinte, maize-teosinte near isogenic lines, and their hybrid were grown in conventional agricultural plots, under uniform tillage and fertility conditions. Throughout the growing season, the researchers sampled rhizosphere soil and analyzed the activity and composition of nitrogen cycling microbes. Combing this data with the genetic panel allowed them to map the region in the teosinte genome that contributed to altered interactions in the soil.
The team identified key introgression regions were enriched in genes linked to secondary metabolism, suggesting that changes in plant chemistry played a role in reshaping how the rhizosphere microbiome functions. Follow-up work at the U of A confirmed the mechanism: chemical signals the roots released, known as exudates, were driving these microbiome changes.
What they found is that when maize carry these teosinte-derived traits, its roots release a different mix of metabolites, or chemical compounds, into the soil.
Looking to the past for future sustainability
Moving forward, Favela and the research team are exploring how these findings can be scaled up to commercial agriculture. One approach may be breeding specific teosinte-derived genes into elite corn varieties. In other words, giving modern maize a "memory boost" of its wild ancestry.
"Part of the study's results suggest that microbiome-shaping plant traits can be reintroduced into modern maize hybrids without reducing yield," Favela said. "It may even improve plant growth and nitrogen use under lower fertilizer conditions."
Another avenue may be developing soil amendments directly related to the natural compounds identified in root exudates, which could provide a targeted, organic method of limiting nitrogen losses.
Rewilding corn may sound like a step backward, but for Favela it's really a matter of biodiversity.
"There's a lot that may have been lost without even knowing. At the end of the day, this work is about having more diversity to work with," he said. "These wild varieties, or just wild plants, have characteristics that can still be used to improve our modern agricultural system."
