Auxin- and hydrogen ion-induced cell wall loosening and cell extension inAvenacoleoptile segments

摘要

Hydrogen ions and auxin induce rapid cell extension ofAvenacoleoptile segments. Nojirimycin (5-amino-5-deoxy-d-glucopyranose), a potent glucanase inhibitor, inhibits auxin-induced growth but does not affect hydrogen ion-induced extension. This inhibitor has little effect on respiration of coleoptile segments but strongly inhibits the in vitro activity ofβ-glucosidase. Hydrogen ions and auxin decreased the minimum stress-relaxation time of the cell wall, indicating that both enhanced cell extension through cell wall loosening. The hemicellulosic glucose content of the cell wall which was decreased by auxin after about a 2-hr lag, was not affected by hydrogen ions. These results suggest that cell wall loosening induced by hydrogen ions may not be the same as that caused by auxin, although both phenomena are represented by the decrease in the minimum stress-relaxation time