Zinc breakthrough could transform crop resilience against climate change

According to the latest findings from scientists described in "Nature," zinc may contribute to safeguarding crops against climate change. This is due to its key role in regulating the nitrogen fixation process by leguminous plants.

Scientists from Aarhus University (Denmark), in collaboration with the Polytechnic University of Madrid and the European Synchrotron Radiation Facility in France, made the discoveries. They determined that zinc, along with the transcription regulator Fixation Under Nitrate (FUN), influences the efficiency of nitrogen fixation by leguminous plants. This discovery could revolutionize legume-based agriculture by optimizing crop efficiency and reducing dependence on synthetic fertilizers.

As explained, FUN responds to "zinc signals" and regulates nitrogen fixation in root nodules, where symbiotic bacteria live. Knowing how zinc and FUN regulate nitrogen fixation could increase its supply, improve yields, and promote more sustainable farming practices. Plants would become more resilient to adverse climate changes and the extreme weather events associated with them. Yields would be more stable, and the demand for artificial fertilizers would decrease. This would make the cultivation of leguminous plants possible in areas where it is not feasible.

"Bacteria can cooperate with leguminous plants, fixing nitrogen from the air in root nodules. However, the nodules are sensitive to environmental influences such as temperature, drought, floods, soil salinity, and high nitrogen concentrations in the soil," explained Jieshun Lin, the study's lead author.

From the farmers' perspective, continuous nitrogen fixation can be a beneficial trait, increasing the availability of nitrogen both for the legumes themselves and for other crops grown in rotation with or after them, which depend on the nitrogen left in the soil after legume cultivation.

"The discovery of zinc's role as a secondary signal in plants is truly remarkable. It is an essential micronutrient and had never before been considered a signal. After examining over 150,000 plants, we have finally identified FUN, shedding light on this fascinating aspect of plant biology," explained Jieshun Lin, who believes that FUN is a vital transcription factor controlling nodule breakdown when soil nitrogen levels are high.

"FUN is regulated by a unique mechanism that directly monitors cell zinc levels. We show that zinc inactivated FUN and released into an active form when zinc levels are low," added Professor Kasper Rojkjar Andersen.

The study's authors believe that the new findings could lay the groundwork for further research, providing new ways to manage agricultural systems, reduce the use of nitrogen fertilizers, and diminish their environmental impact.