Interactions Between Circadian Rhythms, ROS and Redox

Circadian rhythms are endogenous biological cycles with a period of about 24 h. In plants, circadian rhythms have a pervasive influence upon metabolism, physiology and development, yet we are still discovering how these rhythms interact with reactive oxygen species (ROS) generation and signalling. Recent work has identified circadian rhythms of ROS generation and ROS-scavenging enzymes, and there are also circadian rhythms of ROS-generating photosynthesis. Here, we summarise our current understanding of the relationship between the circadian system and ROS, and suggest roles for ROS in circadian signalling between organelles and the circadian regulation of guard cell function. There are circadian rhythms of peroxiredoxin oxidation state that occur in the absence of transcription and translation. It seems that there could be multiple levels of integration between ROS, redox and circadian regulation.