Melatonin delayed leaf senescence induced by WRKY75 in Arabidopsis thaliana

Abstract Leaf senescence, highly regulated by plant hormones and environmental factors, represents the final stage of leaf development. Therefore, the strategies to delay leaf senescence might extent the limitation of growth and yield for crop. Although previous studies had demonstrated the potential of melatonin to delay leaf senescence, its mechanism remained many mysteries. Here, we reported the role of melatonin in delaying WRKY75-induced leaf senescence. Exogenous melatonin increased chlorophyll content and reduced the accumulation of ROS in plants. In addition, it up-regulated the expression of the SNAT gene and increased its melatonin level. Exogenous melatonin also decreased SA level and down-regulated SID2 gene expression. Furthermore, the expression of SAG13 and WRKY75, both positive senescence-related genes, was found to decrease after melatonin treatment. These findings suggest that melatonin counteracts the effects of a network structure comprising SA, ROS, and WRKY75 on senescence, thereby regulating various events related to plant senescence and delaying leaf senescence.