EFFECTS OF MONENSIN ON CELL-WALL METABOLISM OF SUSPENSION-CULTURED FLAX CELLS

Treatment of suspension-cultured flax cells with the ionophore monensi n increased glucan synthase II activity, a plasmalemma endomembrane co mplex, but reduced the activity of inosine-5'-diphosphatase, a Golgi m arker. Activities of glucan synthase I and galactan synthases, endomem brane enzymes that are localized in Golgi apparatus and implicated in cell wall metabolism, were also reduced. At the early end of exponenti al growth, pectin methyl transferase activity, another Golgi enzyme th at controls the charge density of pectins, was not affected. In additi on, the drug caused an increase in cell wall peroxidase activity and a slight reduction in cell wall pectin methyl esterase activity. The pe roxidase activity in the culture medium was not affected.