CHANGES IN WALL-BOUND POLYSACCHARIDASE ACTIVITIES DURING THE CULTURE CYCLE OF A RUBUS-FRUTICOSUS CELL-SUSPENSION

Several hydrolytic enzyme activities were detected in the wall of deve loping cells of Rubus fruticosus in suspension culture. The correspond ing substrates of the enzymes are mostly polysaccharide wall constitue nts, except for chitinase activity. The activities measured when the e nzymes were in the free state or wall-bound showed the positive influe nce of the cell wall micro-environment. Changes in the activities duri ng a cell culture cycle demonstrated that those enzymes acting on xylo glucans behaved differently from the others, and suggest that xylogluc ans undergo modifications in vivo over a longer period of time during the exponential growth phase. The same activities were identified in t he culture medium. Endo-1,4-beta-D-glucanase activities which depolyme rized carboxymethylcellulose (CMC) and xyloglucans (XG) were assayed v iscosimetrically. It was found that XG oligosaccharides exhibited an i nhibitory effect on the depolymerization of xyloglucans but not on tha t of CMC. This suggests that true xyloglucanases are present in the cu lture of Rubus cells.