Role of cell-wall-degrading enzymes in cell-wall loosening in oat coleoptiles.

Effects of auxin (indole-3-acetic acid), fungal β-1,3-glucanase and pectin methylesterase on expansion and on cell wall extensibility, measured by the extensometer technique, of oat coleoptile segments were studied. Pretreatment with these substances for less than 30 min promoted tissue expansion remarkably. Under osmotic stress by 0.25 M mannitol, which prevented uptake of water by the cells, auxin increased DE but not DP in 30- and 60-min incubations. β-1,3-Glucanase or β-1,3-glucanase plus pectin methylesterase also increased only DE under the same conditions. A role of cell-wall-degrading enzymes in initiating cell expansion is therefore suggested.