Hydro-Electrochemical Integration of the Higher Plant – Basis for Electrogenic Flower Induction - Communication in Plants: Neuronal Aspects of Plant Life - page 373

Theseconsiderationssupporttheviewthatactionpotentialsandthecir-
cadian rhythmic organisation of energy metabolism are very early achieve-
mentsintheadaptationoflivingsystemstotheirnaturalenvironment.

25.2
Rhythms in SER as Markers of Photoperiodic
Control and Interorgan Communication
in a Long- and a Short-Day Plant

Both species ( C. murale and C. rubrum ) exhibit a circadian rhythm in the
SER with period lengths of 24.3

0.5 h ( C. mu-
rale ). Flowering plants show a significantly shorter period length in the
SER of 23.44

± 0.5 h ( C. rubrum ) and 27.5 ±

0.66 h ( C. murale ). The period
lengths of LM mirror the kinetics in the SER, displaying similar increases
of frequency in the flower-induced state. While in vegetative plants the
kineticsoftheSERandLMare180 ◦ out of phase, this phase relationship
is shifted after flower induction. Both parameters display clear movement
and growth patterns with photoperiod-specific reactions to “light-on” and
“light-off” signals. Flower induction correlates to a threshold value of stem
growth of 0.6 ( C. rubrum )and4.0( C. murale ) for the ratio of the integral
growth during the dark span over the integral growth in the light span.
Two hours after the beginning of the critical dark period the pattern of cy-
toplasmic pH and Ca 2+ concentration at the apical meristem has changed,
possibly indicating the arrival of the inductive signal (Albrechtová et al.
2001; Walczysko et al. 2000).

± 0.75 h ( C. rubrum ) and 26.6 ±

25.3
Early Changes at the Shoot Apical Meristem
During Flower Induction

Theobservationsjustdiscussedmarkedthebeginningofadetailedkinetics
analysis of early changes at the shoot apical meristem after the beginning of
the inductive darkness. The cell physiological studies, paralleled by molec-
ular studies, are well suited to closing the gap in recent investigations on
the genetic control of flowering via a network of transcription factors,
which led to the discovery of distinct signalling pathways predominantly
in the model plant Arabidopsis (Blázquez and Weigel 2000; Reeves and
Coupland 2000). In fact very little is known about the physiological basis
of the morphological changes during flower induction and early flower de-
velopment. However, recent studies demonstrated changes in carbohydrate