Tip Growth in Root Hairs: Correlating Intracellular Flow with Growth Dynamics Under Mechanical Constraints

Tip growth in plant cells provides a valuable model for investigating how mechanical and biochemical constraints shape cellular dynamics. In this work, root hairs of Arabidopsis thaliana were grown in controlled microenvironments with different stiffness levels, and their behavior was quantified through time-lapse microscopy and optical flow analysis. Results demonstrate that both tip elongation velocity and cytoplasmic streaming decrease significantly in stiffer media, yet maintain a strong positive correlation. Notably, cytoplasmic flow persists even when growth is nearly arrested, indicating that it is not merely a by-product of elongation but may serve additional functions. These findings support an “outside-in” mechanism in which external mechanical resistance regulates not only tip growth but also intracellular organization and dynamics. This study contributes to the development of an integrated physics-based model of tip growth, relevant for understanding plant adaptation to mechanically heterogeneous environments such as compacted or drought-stiffened soils.