AN ELICITOR FROM BOTRYTIS-CINEREA INFLUENCES THE MEMBRANE-POTENTIAL OF PAPAVER-SOMNIFERUM HYPOCOTYLS

The effect of an elicitor isolated from Botrytis cinerea was investiga ted from an electrophysiological point of view using poppy hypocotyl c ells as a target. The membrane potential of poppy hypocotyl cells was monitored by a standard microelectrode technique and found to be in th e range from -120 to -180 mV. The active and passive (diffusional) com ponent were separated by KCN, NaCN, NaCN + SHAM (salicylhydroxamic aci d), anoxia. The treatment with these agents caused a depolarization of the membrane potential to -100 mV, -99 mV, -94 mV, and -86 mV respect ively. The energy-dependent component may reflect the activity of the plasmalemma located H+-extruding pump, as suggested by membrane potent ial hyperpolarization of about -11 mV due to fusicoccin. The fungal el icitor from Botrytis cinerea caused a rapid depolarization of the memb rane potential. The extent of depolarization was dependent on the elic itor concentration. Only the active component of the membrane potentia l was affected by this depolarization. We suppose that the depolarizat ion is a first step in the transduction processes leading to the induc tion of a series of defense responses.