Zinc modulat nitrogen fixation in legumes [by Dr. PB Kale]

 "How Zinc Helps Legumes Adapt to Their Environment"

Schematic diagram: of the screen that resulted in identification of FUN. Mutants producing functionally pink nodules were watered with 10 mM KNO3. Most nodules on wild-type plants became green and senescent, whereas fun mutant plants maintained pink nodules even under high concentrations of nitrate.

 - Plants adapt to changing environmental conditions by adjusting their metabolism and gene expression to maintain fitness.

- In legumes, nitrogen homeostasis is achieved by balancing nitrogen from soil and nitrogen fixation by symbiotic bacteria in root nodules.

- Zinc, an essential plant micronutrient, acts as an intracellular second messenger, linking environmental changes to metabolic activity in root nodules.

- A transcriptional regulator named FIXATION UNDER NITRATE (FUN) acts as a sensor controlled by zinc.

- Zinc controls the transition of FUN between an inactive filamentous structure and an active transcriptional regulator.

- Lower zinc concentrations in the nodule, which occur in response to higher soil nitrate levels, activate FUN by dissociating the filament.

- Activated FUN targets multiple pathways to initiate the breakdown of the nodule.

- The zinc-dependent mechanism provides a concentration readout to adapt nodule function to environmental nitrogen conditions.

- These findings highlight the role of metal ions in integrating environmental signals with plant development.

- Implications include optimizing the delivery of fixed nitrogen in legume crops.

Here is the citation for the article:

Reference:

Lin, J., Bjørk, P.K., Kolte, M.V. et al. Zinc mediates control of nitrogen fixation via transcription factor filamentation. *Nature* (2024). [https://doi.org/10.1038/s41586-024-07607-6]