FREE OR SILICA-BOUND OLIGOKAPPA-CARRAGEENANS ELICIT LAMINARINASE ACTIVITY IN RUBUS CELLS AND PROTOPLASTS

Oligo-kappa-carrageenans prepared by enzymatic hydrolysis of kappa-car rageenan were shown to elicit laminarinase (1,3 beta-D-glucan hydrolas e) activity in Rubus fruticosus cells. Laminarinase activation was inv estigated as a function of the incubation time and of the elicitor dos e and structure. The response to the presence of elicitors was rapid, within 1 h of incubation, and bell-shaped dose-response curves were ty pically observed for the different elicitors. The hexasaccharide from kappa-carrageenan, kappa-neocarrahexaose sulfate, proved the most effe ctive in inducing laminarinase, up to four times the activity of contr ol cells. The comparative behavior of Rubus cells and protoplasts upon incubation in the presence of either free or silica-bound kappa-neoca rrahexaose sulfate is consistent with the involvement of the plasma-me mbrane in signal perception and initiation of biological responses.