UC San Diego

Like most organisms, plants rely on a robust circadian clock to anticipate and adapt to periodic environmental changes. This clock-driven regulation enhances fitness by orchestrating 24-hour rhythms in essential growth and developmental processes. At its core, the circadian clock functions through a negative feedback loop involving the reciprocal regulation of morning-expressed transcription factors, CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), and the evening-expressed TIMING OF CAB EXPRESSION 1 (TOC1). Beyond transcriptional regulation, the stability and activity of these core clock components are intricately controlled at the post translational level. This multilayered regulatory system enables the clock to maintain a precise 24-hour period, ensuring alignment between internal rhythms and environmental cycles—an essential feature for optimal plant fitness. Despite its importance, the molecular mechanisms governing the clock period, especially under environmental stress, remain poorly understood. This study investigates a novel layer of posttranslational regulation within the circadian system, shedding light on how plants sustain rhythmic precision in changing environments.