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Wall relaxation and the driving forces for cell expansive growth
1Department of Biology, Pennsylvania State University, University Park 16802, USA.
Plant Physiology
|January 1, 1987
Summary
In vivo stress relaxation reveals cell wall loosening dynamics. This process, crucial for plant cell expansion, is driven by wall yielding and controlled by wall loosening, not water transport resistance.
Area of Science:
- Plant biology
- Cellular mechanics
- Biophysics
Background:
- Cell expansion is vital for plant growth.
- Cell wall loosening and water uptake are key processes.
- Understanding the mechanics of cell expansion is crucial.
Purpose of the Study:
- To investigate in vivo stress relaxation in plant cells.
- To measure wall yield threshold and physiological wall extensibility.
- To determine the driving force for water uptake during cell expansion.
Main Methods:
- Stress relaxation experiments were conducted.
- New techniques were employed to measure the driving force for water uptake.
- Measurements were taken in elongating stems.
Main Results:
- In vivo stress relaxation reduces turgor pressure and cell wall stress.
- Wall stress is the mechanical driving force for wall yielding.
- The driving force for water uptake during growth is lower than previously estimated (0.3–0.5 bar in stems).
Conclusions:
- Cell wall loosening and yielding primarily control cell expansion rate.
- Hydraulic resistance in the water transport pathway is minimal.
- In vivo stress relaxation offers a novel approach to study cell wall dynamics.