Mechanical Forces and Signal Transduction in Growth and Bending of Plant Roots

Abstract

The growing cell is the elementary unit of the system. The rusult of growth is an increase of its linear dimensions and hence volume. Cell wall elongation and absorption of water are two main constituents of the process. The mechanical forces applied to the cell wall are intracellular liquid pressure (turgor - AS) and forces that owe their origin to the mechanical contact of the wall as the part of the golbal framework with other cell walls and finally with soil and obstacles. The resulting tension produces elastic stretching and promotes an inelastic one, the latter including growth deformation accompanied by deposition of new material. The rheological behaviour of the cell wall Elastic and inelastic elongations The water influx due to water potential difference leads to the elastic elongation of the cell. The insertion of new material ito the wall is stimulated by the tension and lowers this tension as it develops. Inasmuch as the tension is in equilibrium with turgor pressure, the latter also decreases, thus augmenting the water potential. This leads to new water streaming into the cell.