Effect of fusicoccin on plant cell cultures and protoplasts.

We have assayed the capacity of the fungal toxin fusicoccin to induce some of the characteristic effects (acidification of the medium, stimulation of k+, and 3-O-methyl-D-glucose upatke) in cell susppension of Parthenocyssus tricuspidata (Siebold et Zucc.) Planchon, Acer pseudoplatanus L. and Oryza sativa L., and in protoplast suspension prepared from leaves of Nicotiana tabacum L. and Spinacia olearcea L. or from cultures of P. tricuspidata. Evidence is presented showing that all tested biological materials respond to the addition of fusicoccin. The obsrvation that the toxin is also active on protoplasts indicates that cell the wall is not involved in the mechanism of acyion of fusicoccin.