In recent years, melatonin has emerged as a popular research topic in the field of plant biology. Since melatonin is implicated in numerous plant developmental processes and stress responses, the exploration of its roles in regulating various physiological and biochemical processes contributing to plant growth and development under normal or stress conditions has become a rapidly progressing field. Melatonin mostly alleviates the adverse effects of environmental or abiotic stresses such as drought, salinity, low or high temperature and heavy metal stress. In addition, several reports have shown that melatonin induces stress tolerance in plants by modulating gene expression and protein modifications. However, such information is scattered and needs to be reviewed in a timely manner to assess the extent of successes and limitations to direct future research. In this review, we highlight the interactions of melatonin with phytohormones to regulate downstream gene expression, protein stabilization, and epigenetic modification in plants. Finally, we consider the need for, and approach to, the identification of melatonin receptors and components of melatonin signalling pathways