Melatonin biosynthesis and signal transduction in plants in response to environmental conditions

The production of the phytohormone melatonin, how environmental factors affect its biosynthesis, and how it functions in plant responses to stress conditions together with other signaling components are reviewed. Melatonin, the most widely distributed hormone in nature, plays important roles in plants. Many physiological processes in plants are linked to melatonin, including seed germination, anisotropic cell growth, and senescence. Compared with animals, different plants possess diverse melatonin biosynthetic pathways and regulatory networks. Whereas melatonin biosynthesis in animals is known to be regulated by ambient signals, little is known about how melatonin biosynthesis in plants responds to environmental signals. Plants are affected by numerous environmental factors, such as light, temperature, moisture, carbon dioxide, soil conditions, and nutrient availability at all stages of development and in different tissues. Melatonin content exhibits dynamic changes that affect plant growth and development. Melatonin plays various species-specific roles in plant responses to different environmental conditions. However, much remains to be learned, as not all environmental factors have been studied, and little is known about the mechanisms by which these factors influence melatonin biosynthesis. In this review, we provide a detailed, systematic description of melatonin biosynthesis and signaling and of the roles of melatonin in plant responses to different environmental factors, providing a reference for in-depth research on this important issue.

Automated summary

Melatonin, the widely distributed hormone in nature, plays important roles in plant physiology including seed germination, cell growth, and senescence. Plants' responses to environmental factors are influenced by melatonin content dynamics, but the mechanisms remain unclear. Different plants possess diverse melatonin biosynthetic pathways and regulatory networks, highlighting the complexity of melatonin functions in plants.