Receptor-mediated activation of a plant Ca2+-permeable ion channel involved in pathogen defense.
Pathogen recognition at the plant cell surface typically results in the initiation of a multicomponent defense response. Transient influx of Ca2+ across the plasma membrane is postulated to be part of the signaling chain leading to pathogen resistance. Patch-clamp analysis of parsley protoplasts revealed a novel Ca2+-permeable, La3+-sensitive plasma membrane ion channel of large conductance (309 pS in 240 mM CaCl2). At an extracellular Ca2+ concentration of 1 mM, which is representative of the plant cell apoplast, unitary channel conductance was determined to be 80 pS. This ion channel (LEAC, for large conductance elicitor-activated ion channel) is reversibly activated upon treatment of parsley protoplasts with an oligopeptide elicitor derived from a cell wall protein of Phytophthora sojae. Structural features of the elicitor found previously to be essential for receptor binding, induction of defense-related gene expression, and phytoalexin formation are identical to those required for activation of LEAC. Thus, receptor-mediated stimulation of this channel appears to be causally involved in the signaling cascade triggering pathogen defense in parsley.
Zimmermann
S
S
Institut des Sciences Vegetales, Centre National de la Recherche Scientifique, Avenue de la Terrasse, F-91198 Gif-sur-Yvette, France.
Nürnberger
T
T
Frachisse
J M
JM
Wirtz
W
W
Guern
J
J
Hedrich
R
R
Scheel
D
D