Electrical Signals in Long-Distance Communication in Plants - Communication in Plants: Neuronal Aspects of Plant Life - page 287

membrane potential changes alter enzyme activities and even play the role
of transcription factors? Calcium seems a universal messenger or trigger
in most of these processes. The network of mechanisms controlled by Ca 2+
is very large (Hetherington and Brownlee 2004). The AP evolved as a factor
spreading a calcium signal. The kind of response and its degree depend on
the susceptibility of individual cells or tissues to Ca 2+ fluxes. The concepts
of “calcium signature” and “physiological address” seem to apply to APs.
19.2
Conclusions and Future Perspectives
Electrical signals in plants have been registered since the second half of
the nineteenth century. The number of excitable plant species recorded
is increasing. Knowledge about AP mechanism and physiological conse-
quences is accumulating but there is still a broad margin for questions
and speculations. Among the questions that have to be addressed in future
investigations are the following:
- Which ion channels participate in APs? What is their molecular identity?
- How are they regulated in the short term (activation/inactivation) and
how are they modulated (long-term changes in their number and/or
posttranslation modification)?
- What are the roles of the vacuole, the ER and other intracellular struc-
tures in electrogenesis of an AP?
- What is the mechanism of diurnal and seasonal changes in excitability?
- How do plants regulate AP transmission?
- What is the precise mechanism of electrical signal transduction, i.e.,
a coupling between ion fluxes and physiological responses?
Answering these questions will help us to consider electrical signals
in plants as normal phenomena and not as atavisms or extraordinary
processes in extraordinary plants known only to a narrow group of plant
electrophysiologists.
References
Antkowiak B, Engelmann W (1995) Oscillations of apoplasmic K + and H + activities in
Desmodium motorium (Houtt.) merril. pulvini in relation to the membrane potential of
motor cells in leaflet movements. Planta 196:350-356
Biskup B, Gradmann D, Thiel G (1999) Calcium release from InsP 3 -sensitive internal stores
initiates action potential in Chara . FEBS Lett 453:72-76