Dec 29, 2020
Mexican corn variety studied for its ability to use N in the air
Plants need nitrogen to grow. Although the majority of earth’s atmosphere is made up of nitrogen, plants cannot access this form of nitrogen. Instead, farmers must provide nitrogen in other ways, such as expensive synthetic nitrogen fertilizers. Growers of major cereal crops, such as wheat and corn, heavily rely on these fertilizers – which can cost farmers collectively $5 billion a year.
The Foundation for Food & Agriculture Research (FFAR) awarded a $927,581 Seeding Solutions grant to the University of California, Davis (UC Davis) to study a Mexican corn variety, Sierra Mixe, that obtains atmospheric nitrogen with the help of microbes, reducing the need for synthetic fertilizers. Benson Hill provided matching funds for a total $1,855,162 investment.
“The air around us contains nutrients ripe for picking by these next-generation crops,” said Sally Rockey, executive director of FFAR. “Harnessing these nutrients directly through the crop and its associated microbial system would drastically reduce growing costs for farmers. This promising research offers a pioneering new way to fertilize crops while protecting soil health.”
Synthetic fertilizer is not only expensive, but it is also environmentally costly. Synthetic fertilizers erode soil, reduce soil’s ability to hold nutrients and require greater amounts of water to grow crops. The process for creating synthetic nitrogen fertilizer is responsible for an estimated three percent of carbon dioxide emissions. However, Sierra Mixe offers a possible solution to reliance on synthetic fertilizers. This corn plant has a system of airborne roots, in addition to underground roots. The airborne roots secrete a fluid that hosts microbes, which provide the corn with 30-82% of its nitrogen nutrition from the atmosphere.
UC Davis researchers, led by Alan Bennett, are studying Sierra Mixe to determine the process of how the microbial community hosted by the plant provides atmospheric nitrogen to the plant. The research team is breeding the crop and studying the individual plants that are the most and least successful at absorbing atmospheric nitrogen to isolate the genes responsible for this trait. They are also investigating the genomic sequences of the microbes in the plant’s secretions to determine their role in capturing atmospheric nitrogen, as well as how the microbes and plants interact to provide the nitrogen to the plant.
Dr. Bennett commented that “it looks like this is an ancestral trait that was amplified in certain landraces of corn and progressively lost from modern corn varieties. Our research is attempting to identify the regions of the corn landrace genome that determines its ability to associate with nitrogen-fixing microbes so that we have a chance of transferring the trait to modern varieties.”
The researchers are using this information to determine whether these nitrogen-capturing traits can be transferred to conventional corn crops grown in temperate conditions and possibly to other cereal crops. Encouraging crops’ intake of atmospheric nitrogen will not only provide economic and environmental benefits to corn growers in the US, but it could also benefit growers in developing countries who may not have physical or economic access to synthetic fertilizer.
Above, aerial roots of corn from Sierra Mixe. Photo:Alan Bennett/UCDavis