System potentials, a novel electrical long-distance apoplastic signal in plants, induced by wounding.
Systemic signaling was investigated in both a dicot (Vicia faba) and a monocot (Hordeum vulgare) plant. Stimuli were applied to one leaf (S-leaf), and apoplastic responses were monitored on a distant leaf (target; T-leaf) with microelectrodes positioned in substomatal cavities of open stomata. Leaves that had been injured by cutting and to which a variety of cations were subsequently added caused voltage transients at the T-leaf, which are neither action potentials nor variation potentials: with respect to the cell interior, the initial polarity of these voltage transients is hyperpolarizing; they do not obey the all-or-none rule but depend on both the concentration and the type of substance added and propagate at 5 to 10 cm min(-1). This response is thought to be due to the stimulation of the plasma membrane H(+)-ATPase, a notion supported by the action of fusicoccin, which also causes such voltage transients to appear on the T-leaf, whereas orthovanadate prevents their propagation. Moreover, apoplastic ion flux analysis reveals that, in contrast to action or variation potentials, all of the investigated ion movements (Ca(2+), K(+), H(+), and Cl(-)) occur after the voltage change begins. We suggest that these wound-induced "system potentials" represent a new type of electrical long-distance signaling in higher plants.
Zimmermann
Matthias R
MR
Botanisches Institut I, Justus-Liebig-Universität, D-35390 Giessen, Germany.
Maischak
Heiko
H
Mithöfer
Axel
A
Boland
Wilhelm
W
Felle
Hubert H
HH
D000200:Action Potentials / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D004560:Electricity; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D006027:Glycosides / Q000494:pharmacology; D001467:Hordeum / Q000187:drug effects / Q000502:physiology*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D017494:Proton Pumps / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014638:Vanadates / Q000494:pharmacology; D031307:Vicia faba / Q000187:drug effects / Q000502:physiology*
D006027:Glycosides; D017494:Proton Pumps; C007808:fusicoccin; D014638:Vanadates; D002118:Calcium