A Biophysical Model for Plant Cell Plate Development

• Published in: bioRxiv
• Main Authors: Muhammad Zaki Jawaid, Drakakaki, Georgia, Sinclair, Rosalie M, Cox, Daniel
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 22.05.2020
• Subjects: Cell division; Cell walls; Cellulose; Cytoplasm; Free energy; Mathematical models; Maturation; Membrane fusion; Osmotic pressure; Polysaccharides; Spreading; Vesicle fusion
• DOI: 10.1101/2020.05.21.109512

Plant cell division involves de novo formation of a cell plate that partitions the cytoplasm of the dividing cell. Cell plate formation is directed by orchestrated delivery of cytokinetic vesicles via the phragmoplast, vesicle fusion, and membrane maturation to the nascent cell wall by the timely deposition of polysaccharides such as callose, cellulose, and crosslinking glycans. In contrast to the role of endomembrane protein regulators the role of polysaccharides, particularly callose, in cell plate development is poorly understood. It has been suggested that the transient accumulation of callose provides an anisotropic spreading force which helps the transition of earlier, membrane-network cell plate stages into a more mature fenestrated sheet stage. Here we present a biophysical model based on the Helfrich free energy for membranes that models this spreading force. We show that proper cell plate development in the model is possible, depending upon the selection of the bending modulus, with a two-dimensional spreading force parameter of between 2-6pN/nm, an osmotic pressure difference of 2-10kPa, and a range of spontaneous curvature between 0-0.04nm^(-1). With these conditions, we can achieve stable membrane conformations in agreement with observed sizes and morphologies corresponding to intermediate stages of cell plate development. Altogether, our mathematical model predicts that a spreading force generated by callose and/or other polysaccharides, coupled with a concurrent decrease in spontaneous curvature, is vital for the transition of a membrane network to a nearly mature cell plate Competing Interest Statement The authors have declared no competing interest.