Regulation of Photosynthesis by Melatonin Under Optimal and Suboptimal Conditions

Melatonin is a well-known pleiotropic signalling molecule that controls metabolic functions, photosynthesis, and plant growth. Melatonin’s ability to increase plant stress resilience has been studied extensively, but its impact on photosynthesis has received less attention. Here, we have provided a summary of melatonin’s function in plants and how it affects photosynthesis in both normal and stressful environments. Melatonin controls the transcription of associated genes and hormone cues to control the synthesis and breakdown of chlorophyll. Through better photosystem gene transcription, activation of the antioxidant system and promotion of the xanthophyll cycle, it safeguards photosynthesis proteins and upholds the photosynthetic process. Through CAND2/PMTR1, melatonin may control plant stomatal mobility. Lastly, it regulates the metabolism of sugar, the gluconeogenesis pathway, and the breakdown and transport of transient starch to control the photosynthetic carbon cycle.