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Stomatal mechanics II * : material properties of guard cell walls
Author(s) -
WU HSINI,
SHARPE PETER J. H.
Publication year - 1979
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1979.tb00075.x
Subject(s) - isotropy , vicia faba , turgor pressure , guard cell , elongation , anisotropy , elasticity (physics) , materials science , cell wall , elastic modulus , composite material , mechanics , biophysics , ultimate tensile strength , chemistry , physics , optics , botany , biochemistry , biology
In this revised formulation of guard cell mechanics, the material properties of the walls are re‐examined. The observed elastic anisotropy of guard cell walls can be explained by non‐random orientation of the cellulose micellae in the unstrained state. This micellar network is assumed to be loosely embedded in the wall matrix causing a two phase elongation process. In the first phase, the micellar network is ‘loose’ resulting in the walls behaving as an isotropic polymer when stretched. As the volume of the cell expands beyond some threshold, the network becomes ‘tightened’ and a second phase of elongation is initiated. During this anisotropic phase of cell expansion, wall elasticity reflectes changes in the orientation of the network to reduce its load. Using the above theoretical analysis, a turgor‐pressure versus lumen volume relationship is simulated for Vicia faba . The relationship between aperture and water potential for this species is also established. The simulated results agree with the experimental evidence reported for Vicia faba . The estimated shear modulus of elasticity for guard cell walls is 2 MPa (20 bars) which is well within the limits of reported values for other biological tissues.