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

TL;DR

This study reveals how the chloroplast network in the non-motile dinoflagellate Pyrocystis lunula dynamically contracts in response to light, using a combination of experimental observations and mathematical modeling to understand its morphodynamics and auxetic-like properties.

Contribution

It uncovers the light-induced morphodynamics of chloroplast networks and introduces a mathematical model explaining their simple rule-based behavior and auxetic-like properties.

Findings

Chloroplast network contracts in response to light changes

Morphodynamics follow simple rules modeled mathematically

Chloroplast structure exhibits auxetic metamaterial properties

Abstract

Photosynthetic algae play a significant role in oceanic carbon capture. Their performance, however, is constantly challenged by fluctuations in environmental light conditions. Here, we show that the non-motile single-celled marine dinoflagellate Pyrocystis lunula can internally contract its chloroplast network in response to light. By exposing the cell to various physiological light conditions and applying temporal illumination sequences, we find that network morphodynamics follows simple rules, as established in a mathematical model. Our analysis of the chloroplast structure reveals that its unusual reticulated morphology constitutes properties similar to auxetic metamaterials, facilitating drastic deformations for light-avoidance, while confined by the cell wall. Our study shows how the topologically complex network of chloroplasts is crucial in supporting the dinoflagellate's adaptation to varying light conditions, thereby facilitating essential life-sustaining processes.