Cell wall-driven mechanisms underlying emergent growth in phycomyces

Area of Science:

• Cell Biology
• Biophysics
• Mycology

Background:

• Cell wall mechanics govern plant and fungal cell growth and morphogenesis.
• Understanding how cell walls respond to environmental cues for anisotropic growth is crucial but poorly understood.
• The Phycomyces blakesleeanus sporangiophore displays complex growth patterns, including helical tip growth and light responses.

Purpose of the Study:

• To develop a mechanical model explaining the anisotropic growth and complex behaviors of the fungal sporangiophore.
• To investigate the role of cell wall properties in fungal morphogenesis.
• To link molecular organization of the cell wall to observed growth phenomena.

Main Methods:

• Developed a mechanical model incorporating anisotropic elasticity and viscoelastic creep.
• Included tip extension through material deposition in the model.
• Used experimental data and passive mechanical tests (stress relaxation, loading-unloading) to validate the model.

Main Results:

• The model successfully predicts sporangiophore behavior in mechanical tests.
• Attributed rotational inversion and light-stimulated growth to the interaction of fibril-tether network stiffness and bond kinetics.
• Predicted correlations between altered turgor pressure, helical growth, and cell wall dynamics.

Conclusions:

• Fungal morphogenesis is an emergent property of cell wall mechanical characteristics.
• The molecular organization of the cell wall is fundamental to its mechanical properties and resultant growth.
• The model provides a framework for understanding how cell walls translate cues into anisotropic growth.