Dr. Eduardo Blumwald (right) and Akhilesh Yadav, Ph.D., and other members of their team at the University of California, Davis, modified rice to encourage soil bacteria to produce more nitrogen that plants can use. [Trina Kleist/UC Davis]
Researchers used CRISPR to engineer rice to encourage soil bacteria to fix the nitrogen needed for their growth. The findings could reduce the amount of nitrogen fertilizer needed to grow crops, saving American farmers billions of dollars each year and benefiting the environment by reducing nitrogen pollution.
“Plants are incredible chemical factories,” said Dr. Eduardo Blumwald, distinguished professor of plant sciences at the University of California, Davis, who led the study. His team used CRISPR to enhance the breakdown of apigenin in rice. They found that apigenin and other compounds cause bacterial nitrogen fixation.
Their work was published in the journal Plant Biotechnology (“Genetic modification of rice flavonoid biosynthesis enhances biofilm formation and biological nitrogen fixation by soil nitrogen-fixing bacteria”).
Nitrogen is essential for plant growth, but plants cannot directly convert nitrogen from the air into a form they can use. Instead, plants rely on absorbing inorganic nitrogen, such as ammonia, produced by bacteria in the soil. Agricultural production is based on the use of nitrogen-containing fertilizers to increase plant productivity.
“If plants can produce chemicals that allow soil bacteria to fix atmospheric nitrogen, we can engineer plants to produce more of these chemicals,” he said. “These chemicals encourage soil bacteria to fix nitrogen and plants use the resulting ammonium, thereby reducing the need for chemical fertilizers.”
Broomwald’s team used chemical analysis and genomics to identify compounds in rice plants – apigenin and other flavonoids – that enhance the bacteria’s nitrogen-fixing activity.
They then identified pathways for producing the chemicals and used CRISPR gene-editing technology to increase the production of compounds that stimulate biofilm formation. These biofilms contain bacteria that enhance nitrogen transformation. As a result, the nitrogen-fixing activity of bacteria increases and the amount of ammonium available to the plant increases.
“Improved rice plants showed increased grain yield when grown under soil nitrogen-limited conditions,” the researchers wrote in the paper. “Our results support manipulation of the flavonoid biosynthesis pathway as a way to induce biological nitrogen fixation in grains and reduce inorganic nitrogen content. Fertilizer use. Real Strategies.”
Other plants can also use this route. The University of California has applied for a patent on the technology and is currently awaiting it. The research was funded by the Will W. Lester Foundation. In addition, Bayer CropScience supports further research on this topic.
“Nitrogen fertilizers are very, very expensive,” Blumwald said. “Anything that can eliminate those costs is important. On the one hand, it’s a question of money, but nitrogen also has harmful effects on the environment.”
Most of the applied fertilizers are lost, seeping into the soil and groundwater. Blumwald’s discovery could help protect the environment by reducing nitrogen pollution. “This could provide a sustainable alternative farming practice that would reduce the use of excess nitrogen fertilizer,” he said.