Melatonin was firstly found in plants in 1990s.In recent years,the related research on it attracted the attention of many scholars.There were many studies focusing on the content detection method of melatonin in plant,and the physiological function of melatonin in plant was also reported recently.Various methods of melatonin determination were employed for plant samples.The analysis methods included RIA,HPLC,GC,HPLC-MS and GC-MS.Among several methods,HPLC-FD and HPLC-ECD were commonly used to quantify melatonin in plants.The content of melatonin varied in different plant species and organs.Higher content of melatonin was found in seeds and flowers.Nowadays,melatonin was shown to act as a plant growth regulator that directs the differentiation of plant cells,tissues,and organs.It also appears to protect plants against environmental stress from heavy metals,UV radiation,and temperature change.However,the mechanism of its function in plants and the exact synthetic site need to be further investigated.The present paper reviewed some aspects of melatonin in plant:detection,biological synthesis and physiological functions.The potential subjects of melatonin in plant were also proposed.