Plant circadian rhythm in stress signaling

An endogenous regulatory mechanism is required for plants to face diurnal environmental changes as a compensation for their sessile nature. The circadian clock helps plants to anticipate diurnal changes. Many physiological processes in plants like stress acclimatization, hormone signaling, photo morphogenesis, carbon metabolism and defense signaling are currently being explored for their cross linking with the circadian clock. The hypothesis of involvement of the circadian clock in the maintenance of plant homeostasis against these changes was proposed a few decades ago. Several lines of evidence including, phenotypic, interactomic, genomic and metabolomic studies of clock defective mutants strengthened this hypothesis and favored the critical role of the circadian clock in stress acclimatization. Conserved regulatory elements like circadian clock factors, light responsive motifs in the regulatory regions of stress responsive genes and cis-regulatory elements like ABRE and DRE in the clock gene promoters, indicate the involvement of circadian clock and light regulators in the transcriptional regulation of stress response genes and vice versa. Presented here, are the highlights of recent advancements in understanding of the clock–stress physiology in plants. This review examines the experimental evidences, collected over the past few years, to relate circadian clock with abiotic stress tolerance in plants. Insights of this dynamic relation between the clock and stress will improve our current understanding of the multifaceted circadian clock and endogenous mechanism of stress adaptation in plants. © 2017, Indian Society for Plant Physiology.