To introduce the reader to the characteristics and physiological
consequences of electrical signals in plants, we
chose two examples for signals, AP and VP. Their features
were discussed with respect to possible functions in plant
physiology. Overall, the knowledge of electrical signalling
in plants will help to unravel the nature of information
exchange within plant cells and organs, and will give rise to
new and fascinating questions. Future studies will be
directed towards a better understanding of the electrical
(a)
(c)
(b) 175
150
125
100
75
50
25
0
–180 0 180 360
Time (s)
540 720 900
–1.0
–0.5
0.0
0.5
1.0
1.5
2.0
2.5
GH2O (mmol m–2 s–1)
JCO2 (mmol m–2 s–1)
Figure 4. Photosynthetic response of electrical signalling in poplar. (a) Experimental arrangement of gas exchange recordings. The plant
was heat stimulated for 3 s by the flame of a lighter at the base of a mature leaf (*) to evoke a VP (see Fig. 1d). (b) Typical response of
JCO2 and gH2O of the opposite, right leaf at a distance of 15 cm upon flaming of the left leaf. The arrow denotes the instant of injury. At
180 s after stimulation, the net CO2 uptake rate (black graph) decreased immediately and then recovered almost completely after 900 s,
while the gH2O (grey graph) remained stable. (c) Spatio-temporal changes of DF/F′m assessed by chlorophyll fluorescence imaging. The
image area (length, 22 mm; width, 17 mm) covers the center of a leaf while the opposite leaf was stimulated by flaming (*) at a distance of
15 cm similar to the set-up shown in (a). Times are given in relation to the instant of injury (at time 0). Changes in DF/F′m took 240 s to
become apparent. A false colour shift from blue to yellow in the intervein area, equivalent to a reduction of DF/F′m from 0.6 to about 0.2,
indicates the decrease of photosynthesis. The bar translates the false colour code into values of DF/F′m.
Electrical signals in plants 255
signalling control mechanism, the interlink between ion
fluxes and physiological responses, and the molecular identity
of different channel types that participate in electrical
signals.