Auxin and wall extensibility: reversibility of auxin-induced wall-loosening process.

The reversible nature of the auxin-mediated loosening of the cell wall is shown by the ability of respiratory inhibitors to cause the loss of the auxin-induced increase in wall extensibility without affecting the basal extensibility of the wall. This reversibility makes it unlikely that wall loosening is mediated by enzymes, such as cellulase and beta-glucanase, which degrade polysaccharides, since their action is essentially irreversible.