Internal stress controls tendril writhing dynamics in climbing plants

Area of Science:

• Plant biology
• Biophysics
• Mechanics of materials

Background:

• Plant tendrils exhibit complex coiling dynamics influenced by external forces.
• Understanding the interplay between mechanical stress and growth is crucial for plant morphogenesis.

Purpose of the Study:

• To experimentally investigate the writhing dynamics of cucumber tendrils under axial traction.
• To develop a morphoelastic growth model explaining tendril coiling behavior and stress development.
• To identify the critical force threshold governing tendril coiling versus straightness.

Main Methods:

• Experimental application of axial traction forces to cucumber tendrils.
• Growth-field assessments to analyze curvature origins.
• Development of an autotropic morphoelastic growth model using bi-strip geometry.
• Approximation of tendrils as Kirchhoff rods to link curvature with external force.

Main Results:

• At low forces, tendril curvature saturates exponentially over time.
• Above a critical force threshold, tendrils develop intrinsic stress and residual curvature instead of coiling.
• Differential growth was identified as the source of curvature.
• The developed model successfully reproduced the two observed regimes (coiling and straight with intrinsic curvature).

Conclusions:

• Tendril coiling is governed by a balance between applied axial force and internal morphoelastic properties.
• Mechanosensitive growth plays a key role in generating intrinsic curvature.
• The study provides a unified model explaining distinct tendril responses to varying axial loads.