Plants sum and subtract stimuli over different timescales

Abstract

Mounting evidence suggests that plants engage complex computational processes to quantify and integrate sensory information over time, enabling remarkable adaptive growth strategies. However, quantitative understanding of these computational processes is limited. We report experiments probing the dependence of gravitropic responses of wheat coleoptiles on previous stimuli. First, building on a mathematical model that identifies this dependence as a form of memory, or a filter, we use experimental observations to reveal the mathematical principles of how coleoptiles integrate multiple stimuli over time. Next, we perform two-stimulus experiments, informed by model predictions, to reveal fundamental computational processes. We quantitatively show that coleoptiles respond not only to sums but also to differences between stimuli over different timescales, constituting evidence that plants can compare stimuli—crucial for search and regulation processes. These timescales also coincide with oscillations observed in gravitropic responses of wheat coleoptiles, suggesting shoots may combine memory and movement in order to enhance posture control and sensing capabilities.

Morphodynamics of chloroplast network control light-avoidance response in the non-motile dinoflagellatePyrocystis lunula

“…Another photoadaptation mechanism, at a single-cell level, includes the motion and rearrangement of chloroplasts to optimize light absorption or to avoid photo-damage [2,[6][7][8][9][10]. Such strategies are fundamental for survival in fluctuating environments, displaying interesting features such as computation and integration in the context of plant phototropism [11][12][13], and dynamical phase transitions of chloroplast motion [10]. In land plants, the collective motion of individually sensing and moving disk-shaped chloroplasts [9,14] leads to large-scale re-arrangements inside leaf cells, aiming to optimize for light uptake while avoiding strong light.…”