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Hydro-electrochemical integration of the higher plant - basis for electrogenic flower
initiation |
| |
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Edgar Wagner*, Lars Lehner, Johannes Normann, Justyna Veit, Jolana
Albrechtova |
|
Albert-Ludwigs University Institute of Biology Schanzlerstr. 1 D-79104 Freiburg
Germany |
| *email:
Edgar.Wagner@biologie.uni-freiburg.de
|
| |
The integration of activity of Chenopodium plants
on a hydraulic-electrochemical levels is expressed by a diurnal rhythm in resting membrane potential measured
with contact electrodes. Membrane state could be gated by the energy state of cells. From earlier studies we
compiled evidence in favour of a circadian rhythm in overall energy transduction producing a circadian rhythm
in energy charge and redox state (NADP/NADPH). The ratio of metabolic coupling nucleotides would be relatively
temperature independent and thus could fulfill the requirements for precise temperature-compensated time
keeping. The photoreceptor phytochrome, involved in photoperiodic control of development, could via changes in
pyridine nucleotide pool sizes and changes in nucleotide ratios regulate transcription via redox controlled
transcription factors.
Spontaneous action potentials (APs) have been shown to correlate with turgor
controlled growth movements. The accumulation of spontaneous APs at specific times during daily light-dark
spans were recorded giving specific electrophysiograms (EPGs).
There was a switch in predominant
propagation direction of APs along the stem axis (acropetal-basipetal) in the transition from vegetative to
reproductive growth; opposite in long- and short-day Chenopodium plants. The information from EPGs
showing the frequency distribution and polarity changes of spontaneous APs in response to flower inducing and
non inducing photoperiods have been used to induce flowering in non inductive photoperiods by specific timing
and polarity of direct current pulses via contact electrodes. It is anticipated that hydraulic changes at the
apex leading to flower initiation are mediated by a specific hydro-electrochemical communication between
leaves and the shoot apex. |
