Researchers Discover Zinc's Role in Nitrogen Fixation of Legumes

Researchers from Aarhus University (Denmark), Polytechnic University of Madrid (Spain), and the European Synchrotron Radiation Facility in France have discovered that zinc plays a crucial role in the nitrogen fixation process of legumes. The study also found that the transcriptional regulator Fixation Under Nitrate (FUN) is a novel type of zinc sensor, which decodes zinc signals in nodules and regulates nitrogen fixation.

Legume crops engage in symbiotic interaction with rhizobia that fixes atmospheric nitrogen in root nodules. These nodules, however, are sensitive to environmental factors such as temperature, drought, flooding, soil salinity, and high soil nitrogen concentration. The researchers identified that FUN controls nodule breakdown when soil nitrogen concentrations are high. FUN is regulated by a peculiar mechanism that monitors the cellular zinc levels directly. It is also inactivated by zinc into large filament structures and liberated into the active form when zinc levels are low.

“It's truly remarkable to discover zinc's role as a secondary signal in plants. It is a vital micronutrient, and it has never been considered as a signal before. After screening over 150,000 plants, we finally identified the zinc sensor FUN, shedding light on this fascinating aspect of plant biology,” Assistant Professor Jieshun Lin, the study's first author, explains. The researchers are now investigating how zinc signals are generated and decoded by FUN, and looking forward to applying their discoveries to legume crops such as faba bean, soybeans, and cowpea.

For more details, read the article in Aarhus University News and Events.