Researchers from Aarhus University, Denmark, in collaboration with the Polytechnic University of Madrid and the European Synchrotron Radiation Facility, have revealed the role of zinc in enhancing nitrogen fixation in legumes
The study, led by Assistant Professor Jieshun Lin, identifies zinc as a secondary signal that legumes use to optimise nitrogen fixation, a process essential for plant growth and soil fertility.
Zinc’s role in nitrogen fixation
Nitrogen fixation, facilitated by symbiotic bacteria in root nodules, is crucial for converting atmospheric nitrogen into forms usable by plants. However this process is susceptible to environmental factors such as temperature fluctuations, drought, and soil conditions.
“It’s truly remarkable to discover zinc’s role as a secondary signal in plants.” Professor Lin noted. ” 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.”
The role of FUN
Central to this discovery is the role of the transcriptional regulator Fixation Under Nitrate (FUN), identified as a novel zinc sensor within legume nodules. FUN acts as a switch that controls nitrogen fixation efficiency based on zinc availability in the plant.
When zinc levels are low, FUN enhances nitrogen fixation, ensuring sustained plant growth even under stress. Conversely, high zinc levels deactivate FUN, prompting nodule breakdown and conserving resources during periods of soil nitrogen abundance.
Professor Kasper Røjkjær Andersen elaborates, “FUN is regulated by a peculiar mechanism that monitor the cellular zinc levels directly and we show that FUN is inactivated by zinc into large filament structures and liberated into the active form when zinc levels are low.”
Zin signalling in the future
By manipulating zinc levels and understanding FUN’s regulatory role, researchers envision using nitrogen delivery to legumes like faba bean, soybean, and cowpea. This could translate into increased crop yields, reduced dependence on synthetic fertilisers, and expanded cultivation into previously unsuitable regions.
Researchers are eager to look deeper into the mechanisms of zinc signalling and FUN regulation. Their goal is to refine strategies that maximise nitrogen fixation efficiency across diverse agricultural settings.
As global challenges like climate change intensify, innovations in agricultural science are more critical than ever. The newfound understanding of zinc’s role in nitrogen fixation promises not only to support food security but also to direct a greener, more sustainable era of farming.
