Seminars

Growth is ultimately a biomechanical process. In many biological systems, cell expansion follows a typical faster-then-slower trend before cells reaching target sizes, suggesting intricate biomechanical regulations during the process. In plants, cell expansion is driven by the intracellular hydrostatic pressure, or “turgor pressure”, and the resulting cell wall tension, leading to many biophysicists comparing plant cells to “water-filled balloons”. Despite this analogy, the precise role of hydraulic regulations, and their interactions with cell wall biomechanics in plant cell expansion, remain elusive. Here, we propose a simple, osmosis-driven growth model with both mechanical and hydraulic limitations in three-dimensional cells, and show that a faster-then-slower growth trend emerges without additional biological regulations. We further show that strength of biomechanical feedback can modulate growth dynamics. Together, our model predicts a mechano-hydraulic origin of growth dynamics in plant cells and other fluid-filled biological structures like organoids, and provide guidelines for experimental validation.