Elicitor-induced changes in Ca2+ influx, K+ efflux, and 4-hydroxybenzoic acid synthesis in protoplasts of Daucus carota L.

Abstract

Suspension-cultured carrot cells (Daucus carota) and their protoplasts respond to a fungal elicitor prepared from the culture medium of Pythium aphanidermatum by accumulating 4-hydroxybenzoic acid (4-HBA). Protoplasts release the compound into the culture medium. Using 45CaCl2 as a tracer, we were able to demonstrate that the secretion of 4-HBA is preceded by a rapid increase in the Ca2+ influx and a concomitant K+ efflux. If the increased Ca2+ influx was prevented by ethyleneglycol-bis(β-aminoethyl ether)-N,N′-tetraacetic acid, 4-HBA synthesis was inhibited by 70%. These results are discussed with regard to signal transduction from the plasma membrane to the nucleus of carrot protoplasts.