No time to die: plant rhythms under environmental stresses

Environmental stresses are a significant source of crop loss worldwide, making it strategic to understand how plants respond to them, especially in the context of climate change and extreme weather. Plants have a circadian oscillator, also known as the circadian clock, which enables them to adapt to a rhythmic environment. The circadian oscillator allows plants to anticipate rhythmic changes, measure changes in photoperiod, and organise their metabolism within a day. Stress signalling frequently changes the period, phase or amplitude of core circadian oscillator genes. As a result, the outputs of the circadian oscillator change under environmental stress. However, the circadian oscillator also regulates stress responses by gating stress signalling pathways. As a result, the same signal elicits different responses depending on the time of day. This review compiles recent research demonstrating that responses to environmental stresses, including drought, salt, biotic, heat, and chilling stresses, are regulated by, and in turn regulate, the circadian oscillator. Signalling molecules, such as abscisic acid (ABA), jasmonic acid, salicylic acid, and reactive oxygen species (ROS), are essential components of this interplay.