Wall stress relaxation refers to the reduction in tensile stress (force per unit area) in cell walls of plants, fungi and bacteria, as a result of movement or rearrangement of the polymeric network that gives the wall its tensile strength. Wall stress usually comes from cell hydrostatic pressure or turgor pressure, which stretches the cell wall. The wall's resistance to stretching simultaneously creates wall stress and its counter force, turgor pressure. In plant cells, the wall-loosening protein named expansin causes wall stress relaxation by loosening the connections between cellulose microfibrils. The resulting decrease in cell turgor pressure and cell water potential creates the necessary water potential gradient that allows water uptake and expansion of the cell.
Famous quotes containing the words wall, stress and/or relaxation:
“Two prisoners whose cells adjoin communicate with each other by knocking on the wall. The wall is the thing which separates them but is also their means of communication. It is the same with us and God. Every separation is a link.”
—Simone Weil (1909–1943)
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