PLASMA-MEMBRANE EFFECTS OF SALICYLIC-ACID TREATMENT ON CULTURED ROSE CELLS

To test the hypothesis that salicylic acid serves as a signal compound in the chain of events by which cultured rose cells respond to u.v.-C radiation and Phytophthora cell-wall elicitor, we tested the effect o f added salicylate on various plasma membrane-related functions of the cells. Sodium salicylate at 1 mM increased K+ efflux, inhibited the r eduction of ferricyanide, and stimulated the synthesis of H2O2 by the cells. Long-term incubation of cells in nutrient agar containing 1 mM salicylate was lethal, although a 6-hr treatment with salicylate, foll owed by plating, did not reduce plating efficiency. The effects of sal icylate on ferricyanide reduction and plating were not observed with m -hydroxybenzoate and p-hydroxybenzoate, two isomers of salicylate; in contrast, the effects on K- efflux and H2O2 synthesis were more pronou nced with m-hydroxybenzoate than with salicylate. Neither u.v.-C radia tion nor elicitor treatment results in an accumulation of salicylic ac id in rose cells, leading to the conclusion that salicylic acid docs n ot serve as a signal compound in the responses of rose cells to these stressors.