An analysis of the mechanics of guard cell motion

This paper presents a mechanical analysis of the cellular deformations which occur during the opening and closing of stomata. The aperture of the stomatal pore is shown to be a result of opposing pressures of the guard and adjacent epidermal cells. The analysis indicates that the epidermal cells have a mechanical advantage over the guard cells. With no mechanical advantage, an equal reduction in the turgor pressure of both guard and epidermal cells would have a neglible effect upon stomatal aperture. However, due to the mechanical advantage of the surrounding cells, the stomatal aperture increases with equal reductions in turgor, until the adjacent epidermal cells become flaccid. The minimum diffusion resistance of the pore occurs at this point. Further reductions in guard cell turgor lead to closure of the pore. The analysis further demonstrates how the shape, size, wall thickness and material properties of the guard cell walls influence their behavior.