Growth and cell wall changes in azuki bean epicotyls II. Changes in wall polysaccharides during auxininduced growth of excised segments

Changes in cell wall polysaccharides and mechanical properties of the cell wall were examined during IAA-induced elongation growth of excised azuki bean epicotyl segments under different growth conditions. Sucrose promoted IAA-induced cell elongation, but had very little effect on IAA-induced cell wall loosening. In the absence of sucrose, the amount of galactose in the cell wall decreased during the incubation period. IAA enhanced the decrease in the galactose level. In the presence of sucrose, on the other hand, IAA induced increases in the amounts of cellulose, galactose and xylose in noncellulosic polysaccharides. These IAA-induced increases were not observed in the presence of mannitol at concentrations higher than 0.1 M, although cell wall loosening was induced by IAA even in the presence of 0.2 M mannitol.