Organ-to-organ two-way coupling contributes to the stabilization of circadian clock in Arabidopsis.

Circadian clocks increase plant fitness by anticipating periodic environmental changes using unstable temporal information perceived in each tissue/organ. However, little is known about how such local and noisy temporal information regulates global and coordinated plant growth. Here, we show that nutrient-mediated two-way communication between shoots and roots stabilizes circadian rhythms and aids plant growth. The photosynthetic product, sucrose, is transported from the shoot to the root, where it regulates the expression of a clock gene and nutrients uptake rhythms. A lack of nutrient rhythms destabilizes the shoot circadian rhythms and reduces the growth rate. Our mathematical model supports that two-way communication between organs reduces the heterogeneity of the circadian rhythm, thereby maintaining the robustness of the circadian clock in a noisy environment. As with feedback loops in other hierarchies, nutrient-mediated shoot-root interorgan communication of the circadian clock is advantageous for proper growth under fluctuating environmental conditions.

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