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 to 82 percent of its nitrogen nutrition from the atmosphere.
UC Davis researchers, led by Dr. 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, it could benefit growers in developing countries who may not have physical or economic access to synthetic fertilizer.