A new study reveals the crucial role of zinc in regulating nitrogen fixation in legumes via a sensor called FUN. This discovery could help improve crop efficiency and reduce the use of synthetic fertilizers by adapting to environmental and soil conditions.
Researchers have discovered that zinc has a significant impact on the nitrogen fixation process in legumes. This discovery could revolutionize legume agriculture.
Climate change, drought, higher temperatures and other stressors are challenging the sustainability of agriculture. Now, researchers have made an unexpected discovery: zinc plays a crucial role in the response of plants to abiotic stress. This groundbreaking discovery not only sheds light on the intricate mechanisms of plant growth, but also offers the prospect of revolutionizing crop resilience, especially in legume-based agriculture.
Japanese lotus. Credit: Helene Eriksen
Discovery of the role of zinc in nitrogen fixation
Scientists have discovered a critical role for zinc in the nitrogen fixation process of legumes. This discovery, combined with insights into the transcriptional regulator known as Fixation Under Nitrate (FUN), has the potential to transform legume agriculture by improving crop efficiency and reducing reliance on synthetic fertilizers. By delving into the mechanisms by which zinc and FUN control nitrogen fixation, researchers aim to increase nitrogen availability, improve crop yields, and advance more environmentally friendly farming practices.
Legume crops form a symbiotic relationship with rhizobia bacteria, which fix atmospheric nitrogen in root nodules. However, these nodules are vulnerable to various environmental stresses, such as changes in temperature, drought, flooding, soil salinity and increased soil nitrogen levels.
Breakthrough in detecting micronutrients in plants
Researchers from University of Aarhusin collaboration with the Polytechnic University of Madrid and the European Synchrotron Radiation Facility in France, have discovered that legumes use zinc as a secondary signal to integrate environmental factors and regulate nitrogen fixation efficiency. In the study published in Naturethe researchers discovered that FUN is a novel type of zinc sensor, which decodes zinc signals in nodules and regulates nitrogen fixation.
“It is truly remarkable to discover the role of zinc as a secondary signal in plants. It is an essential micronutrient and has never been considered as a signal before. After screening more than 150,000 plants, we finally identified the zinc sensor FUN, shedding light on this fascinating aspect of plant biology,” explains assistant professor Jieshun Lin, the first author of the study.
Jieshun Lin shows the root nodules on a Lotus japonicus. Credit: Helene Eriksen
Revealing the functionality of the FUN protein
In this study, the researcher identifies that FUN is an important transcription factor controlling nodule decomposition when soil nitrogen concentrations are high: “FUN is regulated by a peculiar mechanism that directly monitors cellular zinc levels and we show that FUN is inactivated by zinc in large filament structures and released in the active form when zinc levels are low,” explains Professor Kasper Røjkjær Andersen.
From an agricultural perspective, continued nitrogen fixation could be a beneficial trait that increases nitrogen availability, both for the legume and for co-cultivated or future crops that rely on the nitrogen left in the soil after the legumes have been grown. This helps lay the foundation for future research that will provide us with new ways to manage our agricultural systems and reduce the use of nitrogen fertilizers and their impact on the environment.
Improving agricultural efficiency and sustainability
The implications of this research are significant. By understanding how zinc and FUN regulate nitrogen fixation, researchers can develop strategies to optimize this process in legume crops. This could lead to increased nitrogen delivery, improved crop yields, and a reduced need for synthetic fertilizers, which have environmental and economic costs.
Researchers are now investigating the mechanisms of how zinc signals are generated and decoded by FUN. They look forward to applying these new discoveries to legume crops such as broad beans, soybeans and cowpea.
The research team gathered in the laboratory facilities of Aarhus University. Credit: Helene Eriksen
Reference: “Zinc mediates the control of nitrogen fixation via transcription factor filamentation” by Jieshun Lin, Peter K. Bjørk, Marie V. Kolte, Emil Poulsen, Emil Dedic, Taner Drace, Stig U. Andersen, Marcin Nadzieja, Huijun Liu, Hiram Castillo-Michel, Viviana Escudero, Manuel González-Guerrero, Thomas Boesen, Jan Skov Pedersen, Jens Stougaard, Kasper R. Andersen and Dugald Reid, June 26, 2024, Nature.
DOI file: 10.1038/s41586-024-07607-6
This work was supported by the Enabling Nutrient Symbioses in Agriculture (ENSA) project, funded by Bill & Melinda Gates Agricultural Innovations (INV-57461), the Bill & Melinda Gates Foundation and the Foreign, Commonwealth and Development Office (INV-55767), the Carlsberg Foundation grant (CF21-0139) and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 834221).
Jieshun Lin, Peter K. Bjørk, Jens Stougaard, Kasper R. Andersen, and Dugald Reid are inventors on the basis of a filed patent recording these discoveries.