Stochastic simulations of cortical microtubule dynamics using Cytosim to derive biophysical principles of morphogenesis in Arabidopsis leaf trichomes.

Morphogenesis, a fundamental process in life, orchestrates development of functional anatomical features through intricate cell growth and movement. In plant cells, cortical microtubules (CMT) guide cellulose synthase complex (CSC) along the plasma membrane, thereby influencing cellulose microfibril (CMF) orientation in cell walls. This preferred orientation of CMFs induces anisotropy, leading to asymmetric cell expansion. While current research has comprehensively described fundamental cellular mechanisms involved in morphogenesis, a cohesive modeling framework to accurately simulate CMT dynamics in real 3D cell shapes and assess the resulting alterations in wall architecture is currently absent. Such a framework is crucial to investigate cytoskeleton’s regulatory role in cell growth.

This study establishes a biophysical link between CMT-CSC dynamics and wall structure in Arabidopsis trichomes - an ideal system because they are single-celled, easily accessible, and reproducible. The organization of CMT, predicted in silico using Cytosim - a stochastic simulation suite, is meticulously compared with confocal image data obtained before and after trichome branching. Subsequently, simulation of CMT-CSC interaction enables the calculation of local CMF orientation. This comprehensive framework can be readily applied to other biological systems, and serve as an initial foundation to faithfully reproduce various functional anatomical features experimentally.