Metabolism in Sync: The Circadian Clock, a Central Hub for Light-Driven Chloroplastic and Mitochondrial Entrainment

Aug 25, 2026

Plants align their physiology with daily environmental cycles through the circadian clock, which integrates light and metabolic signals to optimize growth and stress responses. While light entrainment has been extensively studied, emerging evidence highlights the central role of metabolism—particularly from chloroplasts and mitochondria—in tuning circadian rhythms. This review examines bidirectional links between organelle metabolism and the clock, including sugars, ROS, and organic acids as entrainment cues, and retrograde pathways that feedback onto core clock components. It emphasizes chloroplast–mitochondria signal integration and frames light, clock, and metabolism as a coordinated, dynamic network.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages25

Reading Time1 h 3 min

AccessFree to download

Introduction

The plant circadian clock as an integrator

The Plant Circadian Clock

Transcriptional-translational feedback loops (TTFL)

Morning and evening loops

Review Metabolism in Sync: The Circadian Clock, a Central Hub for Light-Driven Chloroplastic and Mitochondrial Entrainment Luis Cervela-Cardona 1,2, *, Marta Francisco 1 and Åsa Strand 2 Academic Editors: Gabriela Toledo-Ortiz, Rossana Henriques and Elena Monte Received: 6 June 2025 Revised: 16 July 2025 Accepted: 6 August 2025 Published: 8 August 2025 Citation: Cervela-Cardona, L.; Francisco, M.; Strand, Å . Metabolism in Sync: The Circadian Clock, a Central Hub for Light-Driven Chloroplastic and Mitochondrial Entrainment. Plants 2025, 14, 2464. [https://doi.org/](https://doi.org/)[ ](https://doi.org/)[10.3390/plants14162464](10.3390/plants14162464) Copyright: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([https://creativecommons.org/](https://creativecommons.org/)[ ](https://creativecommons.org/)[licenses/by/4.0/](licenses/by/4.0/)) . 1 Misión Biológica de Galicia, Consejo Superior de Investigaciones Científicas (CSIC), Apartado 28, 36080 Pontevedra, Spain; [mfrancisco@mbg.csic.es](mfrancisco@mbg.csic.es) 2 Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 901 87 Umeå, Sweden; [asa.strand@umu.se](asa.strand@umu.se) * Correspondence: lmcervela@mbg.csic.es Abstract Plants align their physiology with daily environmental cycles through the circadian clock, which integrates light and metabolic signals to optimize growth and stress responses. While light entrainment has been extensively studied, emerging evidence highlights the central role of metabolism—particularly from chloroplasts and mitochondria—in tuning circadian rhythms. In this review, we explore the bidirectional relationship between organelle metabolism and the circadian clock, focusing on how metabolic signals such as sugars, ROS, and organic acids function as entrainment cues. We discuss how the clock regulates organelle function at multiple levels, including transcriptional, translational, and posttranslational mechanisms, and how organelle-derived signals feedback to modulate core clock components through retrograde pathways. Special attention is given to the integration of chloroplast and mitochondrial signals, emphasizing their synergistic roles in maintaining cellular homeostasis. Drawing on the “three-body problem” analogy, we illustrate the dynamic and reciprocal interactions among light, clock, and metabolism. This perspective underscores the need to reframe the circadian system, not merely as light-driven but also as a central integrator of energy status and environmental cues. Understanding this integrated network is essential to improve plant performance and resilience under fluctuating environmental conditions. Keywords: circadian clock; metabolic entrainment; chloroplast–mitochondria crosstalk; retrograde signaling; light signaling; plant energy metabolism 1. Introduction Plants, as sessile organisms, have acquired an ability to fine-tune their growth, development, and metabolism in response to the ever-changing conditions around them. Central to this adaptation is their capacity to perceive and respond to light, a primary source of energy and a critical environmental cue. Light not only drives photosynthesis, the core of plant metabolism and growth, but it also serves as a key signal for the timing of biological processes. Light signaling is intricately linked to the endogenous cell autonomous timekeeper, the circadian clock, which orchestrates a wide array of physiological activities to align the biological rhythms with the day–night cycle [1] . The circadian clock enables plants to anticipate daily changes and prepare for them in advance, optimizing plant survival and fitness. It regulates the expression of numerous genes, gating key processes such as photosynthesis, hormone signaling, and leaf movement to specific times of the day [2,3] . Th

FAQs

What signals besides light can entrain the plant circadian clock?

The review highlights metabolic signals originating from chloroplasts and mitochondria, including sugars, ROS, and organic acids, as entrainment cues.

How do organelles communicate with the circadian clock?

Organelle metabolism tunes circadian rhythms by influencing clock function at transcriptional, translational, and posttranslational levels, while organelle-derived signals feedback through retrograde pathways.

Why is chloroplast–mitochondria integration emphasized in this review?

Because chloroplast and mitochondrial signals work synergistically to maintain cellular homeostasis and to refine how the clock and metabolism coordinate over day–night cycles.

Aug 25, 2026

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