The Role of Melatonin in Fungi

Melatonin, also known as the sleep hormone, plays a critical role in regulating our sleep-wake cycles, influencing our biological rhythms, and ensuring we get a good night’s rest. But this remarkable hormone extends far beyond human health. Interestingly enough, melatonin is not only a luxury reserved for the animal kingdom, as it is found in a wide array of organisms, from plants to bacteria and even some fungi.

How does melatonin impact fungi?

Scientists have observed melatonin in various fungal forms, from basic free-living unicellular organisms to more complex basidiomycetous fungi. 

Melatonin serves several vital functions in fungi, influencing their growth, development, and response to environmental stresses. Notably, melatonin is essential to the process of morphogenesis, which is how fungi form their structure, including their network of mycelium and their fruiting bodies. Morphogenesis is required for fungal growth and reproduction, and melatonin plays a major role in regulating these developmental phases and ensuring that fungal structures are formed correctly.

Furthermore, since melatonin is a powerful antioxidant, it helps fungi combat stress from oxidization and UV radiation by neutralizing harmful molecules that can cause cellular damage. It has also been found to enhance fungi’s ability to withstand heavy metal-induced stress, as certain antioxidant enzymes reduce the accumulation of heavy metals in fungal cells. 

Interestingly, the way melatonin synthesizes in fungi for these defense mechanisms is strikingly similar to that in plants. Although not entirely identical, this process demonstrates the biological convergence and necessary role of melatonin across different life forms (1).

Potential applications

Since melatonin can influence the growth of fungi, it can be used to benefit agricultural practices. In mushroom cultivation, for example, melatonin can be used to increase production. One previous study found that the external application of melatonin could increase the number of early-stage mushroom growths called primordia, providing a better chance at an overall increase in mushroom yield (2).

This method could also be used with fungi that interact symbiotically with crops, also known as mycorrhizal fungi. These types of fungi enhance the nutrient absorption capacities of plant roots, leading to better crop growth and yield. By treating mycorrhizal fungi with melatonin, it’s possible to boost these beneficial effects and lead to stronger and more resilient crops that can better withstand external stressors like pests and diseases. 

Additionally, melatonin’s role in fungi stress tolerance could be used to develop fungi-based biocontrol agents to protect crops from pathogens and pests instead of using chemical pesticides. Certain fungi are known for their ability to attack soil pathogens, and the application of melatonin may further enhance their stress resistance and improve their growth, providing a more effective and ecologically friendly means of maintaining crop health (3).

While researchers are still in the works of understanding the full scope of melatonin’s impact on fungi and its practical applications, the initial findings are quite promising and suggest a multitude of benefits that could transform agricultural practices and enhance sustainability.

References

1. Chakraborty, Debraj, Adrija Mukherjee, Atanu Banerjee, and Nirmalendu Das. 2024. “Role of Melatonin in Fungi, with Special Emphasis to Morphogenesis and Stress Tolerance.” South African Journal of Botany 166 (March): 413–22. https://doi.org/10.1016/j.sajb.2024.01.045.
2. Wang, Jinjie, Xianglian Chen, Chenghua Zhang, Min Li, Chengyuan Sun, Ning Zhan, Xueshuang Huang, Tai­-Hui Li, and Wang-Qiu Deng. 2021. “Biosynthetic Pathway and the Potential Role of Melatonin at Different Abiotic Stressors and Developmental Stages in Tolypocladium Guangdongense.” Frontiers in Microbiology 12 (October). https://doi.org/10.3389/fmicb.2021.746141.
3. Yu, Yang, Zhaowei Teng, Zongmin Mou, Yan Lv, Tao Li, Suiyun Chen, and Dake Zhao. 2021. “Melatonin Confers Heavy Metal-Induced Tolerance by Alleviating Oxidative Stress and Reducing the Heavy Metal Accumulation in Exophiala Pisciphila, a Dark Septate Endophyte (DSE).” BMC Microbiology 21 (1). https://doi.org/10.1186/s12866-021-02098-1.