Abstract
The nature and characteristics of the electrical response to wounding in the
woody plant Vitis vinifera L. were examined. Following
burning of a small area of a leaf, bioelectrical events spread throughout the
shoot. The heat wound triggered stem deformations
(widening–contraction), which preceded changes in biopotentials and that
are interpreted as reflecting wound-induced hydraulic signals. It also caused
marked decrease of extracellular resistance in stem tissues, starting about 15
s after stimulation, while intracellular resistance did not show any
modification. Under an N2 atmosphere (hypoxic
conditions), action potentials disappeared and the amplitude of variation
potentials decreased approximately 50%. At saturating humidity
variation potentials were completely eliminated, while action potentials were
evident. Taken together, the results demonstrate that action and variation
potentials differ both in their mechanism of propagation and electrogenic
nature. Action potentials are ‘genuine’ self-propagating
electrical signals travelling at a velocity of about 10 cm
s-1, with a metabolic nature involving active components
(electrogenic pumps). Variation potentials are a ‘local’ response
to the passage of an hydraulic wave. Results support the hypothesis that both
ion channels and pumps are involved in variation potential depolarisation.
Subject
Plant Science,Agronomy and Crop Science
Cited by
93 articles.
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