Circadian clocks allow living organisms to anticipate and adapt to the daily variations of the environment. The interlocked feedback loops of the transcription factors network in the plant clock generate oscillations with expression peaks at specific times of the day. In this work, we explore the effect of molecular noise on the behavior of the plant circadian clock through numerical simulations. The influence of system size, photoperiod, and mutations of clock genes on the robustness of the oscillations are discussed. Our simulations show that the oscillations remain robust when the mRNA and protein levels are in the range of a few hundreds molecules. Entrainment by light–dark cycles enhances the robustness compared to constant conditions. Multiple light inputs and inter-cellular coupling also contribute to the robustness of the oscillations. The comparison between deterministic and stochastic simulations of single and double mutants shows that stochasticity does not qualitatively affect the behaviour of mutants but that they do not have the same robustness to noise. Finally, the model shows that noise can induce transitions between two limit cycles in a birhythmic clock mutant.

生物钟允许生物体预测和适应环境的日常变化。植物时钟中转录因子网络的互锁反馈回路在一天中的特定时间产生具有表达峰值的振荡。在这项工作中，我们通过数值模拟探索了分子噪声对植物生物钟行为的影响。讨论了系统大小、光周期和时钟基因突变对振荡稳健性的影响。我们的模拟表明，当 mRNA 和蛋白质水平在数百个分子的范围内时，振荡仍然很稳健。与恒定条件相比，明暗循环的夹带增强了稳健性。多个光输入和细胞间耦合也有助于振荡的稳健性。单突变体和双突变体的确定性和随机模拟之间的比较表明，随机性不会定性地影响突变体的行为，但它们对噪声没有相同的鲁棒性。最后，该模型表明噪声可以诱导生物节律时钟突变体中两个极限周期之间的转换。