Plant mechanics of growth: multi-scale perspective

Force is the sculptor of life. Plant growth is driven by mechanical processes operating across multiple scales, from the cellular to the organ level. This review explores these processes from a multi-scale perspective. It begins with the historical development of mechanics models for plant cell growth, with a particular focus on the classical Lockhart equation. The structure and properties of the cell wall are then scrutinized, emphasizing its regulatory role in cell growth and how its viscosity, elasticity, and plasticity influence cell expansion and morphogenesis. Next, this review investigates mechanical interactions at the cell-tissue interface, focusing on how cellular stress and tissue structural characteristics influence plant growth through cross-scale mechanisms. At the macroscopic scale the mechanical principles governing tissue growth and morphology are analyzed, illustrating how mechanical forces and differential growth shape organ development. Additionally, the recently developed biomechanical morphogenesis approach, based on topology optimization, is explored. By synthesizing plant growth models across different scales, this review enhances our understanding of biomechanics and provides key insights into plant growth. The knowledge gaps identified in this article offer a roadmap for future research in the field.