Can force Generation in plant cells be predicted with Lockhart's Law?

Through turgor pressure, plant cells generate forces that far exceed those attainable by muscle contraction in animals. Maintaining turgor while growing involves a constant production of osmoticum to drive water into the cells, making it possible to pierce the soil and remain upright against the pull of gravity. Thus, water movements are key to understanding the different strains and stresses to which plant cells subject themselves. In the case of Characean internodal cells, the turgor pressure positively regulates the growth rate phenomenologically abiding to a threshold fluid like constitutive law, coined Lockhart’s law.

Ignoring other regulations, this framework provides one of the simplest descriptions of the interaction between a growing cell and its environment. Combining water potential equilibrium to Lockhart’s law, we quantitatively predicted how a growing cylindrical cell which exhibits elongation and twisting will interact with either a spring or a torsion spring. To test our predictions and evaluate our hypothesis robustness, we mounted an experimental set-up to monitor every quantity involved in Lockhart’s growth law and their evolution during the interaction with an obstacle by combining a pressure probe to monitor turgor in real time and home-made glass obstacles of known rigidity to measure the force exerted at the cell’s apex.