“Nitrogen fertilizers are very, very expensive,” Blumwald said. “Anything you can do to eliminate those costs is important. The problem is money on the one hand, but there are also the harmful effects of nitrogen on the environment.”
A new way to natural manure
Blumwald’s research focuses on increasing the conversion of nitrogen gas in the air into ammonium by soil bacteria – a process known as nitrogen fixation.
Legumes such as peanuts and soybeans have root nodules that can use nitrogen-fixing bacteria to supply ammonium to the plants. Cereal plants such as rice and wheat do not have that ability and depend on absorbing inorganic nitrogen, such as ammonia and nitrate, from fertilizers in the soil.
“If a plant can produce chemicals that cause soil bacteria to fix atmospheric nitrogen gas, we can adapt the plants to produce more of these chemicals,” Blumwald said. “These chemicals will induce bacterial nitrogen fixation in the soil and the plants will utilize the ammonium formed, reducing the amount of fertilizer used.”
Blumwald’s team used chemical screening and genomics to identify compounds in rice plants that enhanced the bacteria’s nitrogen-fixing activity.
They then identified the pathways that generate the chemicals and used gene editing technology to increase the production of compounds that stimulate the formation of biofilms. Those biofilms contain bacteria that increase nitrogen conversion. This increased the nitrogen-fixing activity of the bacteria, as did the amount of ammonium in the soil for the plants.
“Plants are incredible chemical factories,” he said. “What this could do is provide a sustainable alternative agricultural practice that reduces the use of excessive nitrogen fertilizers.”
The path can also be used by other plants. A patent application on the technique has been filed by the University of California and is pending.
Dawei Yan, Hiromi Tajima, Howard-Yana Shapiro, Reedmond Fong and Javier Ottaviani of UC Davis contributed to the research paper, as did Lauren Cline of Bayer Crop Science. Ottaviani is also a research associate at Mars Edge.