Osmotic concentration, cell elongation

Sometimes, but certainly not always, a correlation can be found between intensity of cell elongation and concentration of osmotically effective substances in the vacuole. Thus, we are left with the alternative decrease of wall pressure. This lowering of wall pressure is achieved by an enhancement of the plastic flexibility of the cell wall. Crosslinks between the macromolecules of the components of the cell wall are broken, the wall is plastically extended and after elongation has occurrred new crosslinks are formed. In the cell walls of the elongation zones of the oat coleoptile different kinds of macromolecules are found (Table 8). They can all be linked to each other through functional groups in the different molecules, i.e. they can form crosslinks. 

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