Circadian gating of autophagy: Not a continuous process?

Autophagy has long been considered or viewed as a stress-induced or constitutive cellular process, supporting homeostasis through the degradation and recycling of damaged components. However, emerging evidence challenges this traditional view, revealing that autophagy is not continuously active in plants but follows a time-gated phenomenon orchestrated by the plant's internal clock. Recent studies show that core circadian regulators, including TOC1, PRRs, COR and LUX, repress autophagy-related genes (ATGs) expression during daytime (after zeitgeber time 0 (ZT0) to before ZT15), actively gating the process and becoming activated post-ZT15, when cellular sugar levels decline, correlated with SnRK1 activation. This circadian gating aligns autophagic flux with predictable metabolic transitions, positioning it as an anticipatory mechanism. In this correspondence article, we combine molecular and physiological data that collectively support a paradigm shift: autophagy in plants operates as a clock-directed, non-continuous process. Understanding this rhythmic coordination offers new strategies to leverage circadian-autophagy coupling for engineering spatiotemporal stress resilience in crops.