Melatonin Rewires Plant Metabolism to Survive Stress, Review Finds

Melatonin, the hormone famous for regulating sleep in animals, is quietly becoming one of the most talked-about molecules in plant science. A new review published in Plant Cell Reports by Barket Hussain, Hatice Colgecen, Havva Karahan and Qazi Fariduddin brings together a decade of evidence showing that this small indoleamine acts as a master switch in plants, reprogramming primary and secondary metabolism so that crops can withstand drought, salinity, heat, cold, heavy metals and pathogens. The authors argue that melatonin is not merely an antioxidant that mops up damaging molecules after the fact, but a genuine signalling regulator that coordinates reactive oxygen species, nitric oxide and a whole suite of phytohormones to integrate stress perception with physiological adaptation.

The central idea of the review is metabolic reprogramming. Because plants are sessile organisms, they cannot flee environmental challenges; instead they must reorganise their internal chemistry in place. When stress strikes, cellular homeostasis collapses, photosynthesis falters and energy flows are diverted from growth toward defence. Melatonin, chemically N-acetyl-5-methoxytryptamine, intervenes at multiple points in this process. It shifts carbon fluxes through carbohydrate metabolism, alters amino acid biosynthesis, adjusts energy metabolism and stimulates the production of secondary metabolites such as phenolics, flavonoids and anthocyanins. The net effect is an accumulation of osmoprotectants, antioxidants and defence-related compounds that buffer the cell against damage and keep essential functions running under conditions that would otherwise be lethal.

One of the most striking aspects of the review is its emphasis on how modern analytical chemistry has transformed the field. High-throughput platforms such as liquid chromatography coupled to mass spectrometry, gas chromatography coupled to mass spectrometry and nuclear magnetic resonance spectroscopy now allow researchers to profile hundreds of stress-responsive metabolites simultaneously. These metabolomics approaches reveal, at a systems level, exactly which metabolic networks melatonin touches. When combined with transcriptomics, which measures changes in gene expression, and proteomics, which tracks shifts in protein abundance, metabolomics provides a multi-layered picture of how a single molecule can orchestrate such far-reaching changes. The authors highlight that this multi-omics integration is the key to understanding melatonin-mediated stress tolerance rather than viewing it as a collection of isolated physiological effects.

The mechanistic details are considerable. Melatonin biosynthesis in plants proceeds from tryptophan through a series of enzymatic steps, with serotonin N-acetyltransferases and related enzymes acting as key control points. Recent work cited in the review shows that manipulating these enzymes, for example by enhancing the expression of SNAT1 in kiwifruit, boosts melatonin biosynthesis, promotes growth and improves salt stress tolerance. Copy number variation in ASMT and COMT genes appears to drive differences in melatonin dosage between species, suggesting that breeders could select for naturally high-melatonin lines. This genetic dimension turns what might seem like an abstract biochemical story into a practical breeding target for climate-resilient agriculture.

Equally important is melatonin’s role as a signalling hub. The review describes extensive crosstalk with abscisic acid, auxin, cytokinin, gibberellin, ethylene, jasmonic acid, salicylic acid and strigolactones. In tomato, jasmonate and melatonin act synergistically to potentiate cold tolerance, while abscisic acid participates in melatonin-induced chilling tolerance in cucumber by regulating photosynthesis and the antioxidant system. In Arabidopsis, melatonin antagonises cytokinin responses to stimulate root growth, and cytokinin in turn modulates phytomelatonin responses under high light. Melatonin also represses auxin synthesis and polar auxin transport to regulate root meristem activity, and it can suppress ethylene biosynthesis during apple fruit ripening by inhibiting the transcription factor MdREM10. These interactions show that melatonin sits at a genuine crossroads of plant hormone networks, capable of both amplifying and damping specific hormonal signals depending on the stress context.

Reactive oxygen species and nitric oxide form another critical layer of this signalling web. Stress conditions cause bursts of reactive oxygen that damage membranes, proteins and DNA, but these molecules also serve as signals. Melatonin and its metabolites are exceptionally efficient radical scavengers, and the review documents how melatonin improves ROS metabolism and antioxidant defence responses in systems ranging from tomato seedlings exposed to copper to maize facing chromium toxicity. At the same time, melatonin engages nitric oxide in a stress-state-dependent signalling module, as recent work in Trends in Plant Science describes, allowing the plant to fine-tune its redox balance rather than simply eliminating all reactive species. This dual role, detoxifier and signal modulator, distinguishes melatonin from conventional antioxidants.

The review also covers melatonin’s contribution to defence against living attackers. In Arabidopsis, comparative metabolomic analysis has implicated sugars and glycerol in melatonin-mediated innate immunity against bacterial pathogens. Melatonin activates plant defence against root-knot nematodes through the jasmonate pathway, enhances resistance to Botrytis cinerea in tomato through a hierarchical cascade involving jasmonic acid and nitric oxide, and promotes jasmonic acid and phlorizin biosynthesis in pear against Botryosphaeria dothidea. Postharvest applications are particularly promising: melatonin treatment strengthens blueberry fruit defences by modulating jasmonic acid signalling and phenylpropanoid metabolites, and it improves chilling tolerance of peach fruit during cold storage by affecting jasmonate content and cell wall stability. There is even emerging evidence that melatonin may act as a natural antiviral compound in plant biocontrol.

Heavy metal and contaminant stress receives detailed treatment as well. Melatonin mitigates nickel toxicity in tomato seedlings by improving nutrient uptake, root architecture and antioxidant potential; it reduces heavy metal accumulation in pepper; it alleviates mercury toxicity in moss by modulating redox homeostasis and the urea cycle; and it helps rice cope with arsenic by reinforcing antioxidant defences and secondary metabolism. In alfalfa, melatonin alleviates aluminium toxicity, and in tomato, anthocyanin synthesis proves critical for melatonin-induced chromium tolerance. Combined applications are a recurring theme: melatonin with strigolactone mitigates salinity in maize through antioxidant defence, osmotic adjustment and ion homeostasis; melatonin with hydrogen sulfide modulates secondary metabolites and metal sequestration in arsenic-stressed tomato; and melatonin with salicylic acid improves drought performance in Brassica napus.

For agriculture, the practical implications are substantial. Exogenous melatonin application, whether as foliar spray, seed treatment or postharvest dip, has repeatedly improved crop performance under stress. In cotton, combined abscisic acid and melatonin application protects carbohydrate metabolism and yield under drought. In sugar beet, melatonin with jasmonic acid protects against heat stress by modulating enzymatic antioxidants and organic osmolytes. In sorghum, exogenous melatonin improves drought responses through defined physiological mechanisms. The review frames these findings within the broader push toward climate-smart agriculture, noting that melatonin-enabled omics approaches are helping researchers understand plant responses to single and combined stresses, which is precisely the kind of multifactorial challenge that field crops increasingly face as weather patterns become more erratic.

The authors conclude that integrating metabolomics with transcriptomics and proteomics offers the clearest path forward for decoding melatonin’s mechanisms and translating them into strategies for enhancing crop resilience and productivity. What was once considered merely an animal sleep hormone has turned out to be a versatile green signal, one that plants deploy to rewire their metabolism in the face of adversity. As sequencing costs fall and mass spectrometry becomes ever more sensitive, the coming years should reveal the precise regulatory circuits through which melatonin operates, opening the door to crops engineered or bred to harness this molecule’s remarkable protective chemistry. For a world where heatwaves, droughts and saline soils threaten harvests with growing frequency, melatonin’s journey from night hormone to agricultural ally may prove to be one of the more consequential stories in plant biology.

Subject of Research: Melatonin-mediated metabolic reprogramming and stress adaptation in plants

Article Title: Melatonin-mediated metabolic reprogramming and stress adaptation in plants

Article References: Hussain, B., Colgecen, H., Karahan, H., & Fariduddin, Q. (2026). Melatonin-mediated metabolic reprogramming and stress adaptation in plants. Plant Cell Reports, 45(11), Article 335. https://doi.org/10.1007/s00299-026-04016-z

Image Credits: AI Generated

DOI: 10.1007/s00299-026-04016-z

Keywords: melatonin, phytomelatonin, metabolic reprogramming, metabolomics, multi-omics, plant stress tolerance, reactive oxygen species, nitric oxide, phytohormone crosstalk, secondary metabolites, crop resilience, Plant Cell Reports