RT Journal Article
SR Electronic
T1 Chloroplasts in plant cells show active glassy behavior under low light conditions
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.04.15.488438
DO 10.1101/2022.04.15.488438
A1 Nico Schramma
A1 Cintia Perugachi Israëls
A1 Maziyar Jalaal
YR 2022
UL http://biorxiv.org/content/early/2022/09/28/2022.04.15.488438.abstract
AB Plants have developed intricate mechanisms to adapt to changing light conditions. Besides photo- and heliotropism (the differential growth towards light and the diurnal motion with respect to sunlight), chloroplast motion acts as a fast mechanism to change the intracellular structure of leaf cells. While chloroplasts move towards the sides of the plant cell to avoid strong light, they accumulate and spread out into a layer on the bottom of the cell at low light to increase the light absorption efficiency. Although the motion of chloroplasts has been studied for over a century, the collective organelle-motion leading to light adapting self-organized structures remains elusive. Here, we study the active motion of chloroplasts under dim light conditions, leading to an accumulation in a densely packed quasi-2D layer. We observe burst-like re-arrangements and show that these dynamics resemble systems close to the glass transition by tracking individual chloroplasts. Furthermore, we provide a minimal mathematical model to uncover relevant system parameters controlling the stability of the dense configuration of chloroplasts. Our study suggests that the meta-stable caging close to the glass-transition in the chloroplast mono-layer serves a physiological relevance: chloroplasts remain in a spread-out configuration to increase the light uptake, but can easily fluidize when the activity is increased to efficiently rearrange the structure towards an avoidance state. Our research opens new questions about the role that dynamical phase transitions could play in self-organized intracellular responses of plant cells towards environmental cues.Competing Interest StatementThe authors have declared no competing interest.