C. Moyen et E. Johannes, SYSTEMIN TRANSIENTLY DEPOLARIZES THE TOMATO MESOPHYLL CELL-MEMBRANE AND ANTAGONIZES FUSICOCCIN-INDUCED EXTRACELLULAR ACIDIFICATION OF MESOPHYLL TISSUE, Plant, cell and environment, 19(4), 1996, pp. 464-470
The plant polypeptide signal systemin induces proteinase inhibitor syn
thesis in tomato leaves. We show here that systemin elicits a transien
t depolarization of the tomato mesophyll cell membrane. Furthermore it
triggers a transient decrease in the external pH of the mesophyll tis
sue which is followed by a sustained pH increase. In the presence of f
usicoccin (which has been shown to antagonize the synthesis of protein
ase inhibitors) the depolarization and transient H+ efflux are attenua
ted whereas the slower phase of the sustained electroneutral H+ influx
persists. These results suggest that systemin-induced changes in ion
transport play a role in the early phases of systemin signal transduct
ion.