Role of the circadian clock in fine-tuning the process of leaf senescence in plants

Leaf senescence is a developmental process and a critical evolutionary strategy for fitness in plants, involving highly organized regulatory mechanisms. Many environmental signals as well as internal developmental aging trigger leaf senescence. Circadian clocks provide timing information for the adaptation of organisms to changing environmental conditions via dynamic metabolic and physiological regulatory networks. Interactions between aging and the circadian clock have been well characterized in animals. In plants, recent studies reveal similar interactions between leaf senescence and the circadian clock, supporting the evolutionary conservation of these interactions in both animal and plant kingdoms. In this review, we discuss the major clock components and senescence regulators that connect these two regulatory mechanisms, and the significance of this relationship in the plant life history.