Rhythmic Leaf Movements Research Articles

Phase relations between the circadian leaf movement rhythm and its zeitgeber within the range of entrainment in the cotton plant,Gossypium hirsutumL.

Abstract The leaf movement rhythm of Gossypium hirsutum L. (cv. Lakshmi) could be entrained to 24 h LD cycles with different photofractions varying from 4 to 20 h such that the night peak position of the rhythm occurred during darkness. The phase angle (ψ) of the rhythm varied in a regular manner with different photoperiods of a 24 h LD cycle. Under 24 h LD cycles with different photoperiods, the leaf movement shows probable evidences for the concurrent participation of a ‘light‐on’ and ‘light‐off rhythm.

Action of gibberellic acid in effecting phase shifts of the circadian leaf-movement rhythm of a cotton plant, Gossypium hirsutum

Pulses of gibberellic acid (GA3) offered at various phases of circadian leaf-movement rhythms in the cotton plant, Gossypium hirsutum, effected advance phase shifts of varying magnitude. Neither the quality nor the amount of these phase shifts was altered by the background illumination, suggesting an apparent absence of synergistic action of the light and gibberellic acid.

Leaf Movements in Sicklepod (Cassia obtusifolia) in Relation to Herbicide Response

Sicklepod (Cassia obtusifoliaL.) leaves and leaflets changed their orientation throughout 24-h periods. These endogenously controlled rhythmic movements resulted in dramatic changes in the percent projected leaf area (PPLA), the leaf area observed from directly above and expressed as a percentage of the total actual leaf area. The PPLA of sicklepod varied more than seven-fold throughout a 24-h period, being greatest during the day and least at night. Control of sicklepod with linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] applied postemergence at intervals throughout 24-h periods was greater from daytime applications than from late evening, night, and early morning applications. Percent control was highly correlated with PPLA, suggesting that rhythmic leaf movements and the resulting change in PPLA could be an important factor in determining the efficacy of postemergence herbicide applications on sicklepod by altering the area of the leaf surface most likely to intercept and retain herbicide spray from an over-the-top application. In addition to endogenously controlled leaf movements, we observed leaf movements caused by simulated cloud cover (80% shading). Shading increased the PPLA of sicklepod, suggesting that more leaf surface might be exposed to an over-the-top spray during cloudy periods than during sunny periods.

Rhythmic Leaf Movements of Some Common Weeds

In growth chamber studies, we measured the movement of cotyledons and leaves or leaflets in seedlings of nine weed species to determine: the magnitude of movement, whether movements followed a rhythmic pattern, and if rhythmic movements were endogenously controlled. Seedlings were always entrained under a 15-h light:9-h dark regime. Measurements were made at 3-h intervals for 3 to 4 days under four light regimes: alternating 15-h light:9-h dark; continuous light; one 15-h light:9-h dark span, followed by continuous light; and a 15-h light:9-h dark regime, in which the dark span was advanced 9 h (phase shift) when measurements were begun. No clearly defined pattern of leaf movement was found in wild mustard [Brassica kaber(DC.) L. C. Wheeler var.pinnatifida(Stokes) L. C. Wheeler]. Daily rhythmic leaf movements that did not appear to be endogenously controlled were found in redroot pigweed (Amaranthus retroflexusL.) and black nightshade (Solanum nigrumL.). Circadian rhythmic leaf movements that appeared to be under endogenous control were found in jimson-weed (Datura stramoniumL.), common lambsquarters (Chenopodium albumL.), common cocklebur (Xanthium pensylvanicumWallr.), prickly sida (Sida spinosaL.), sicklepod (Cassia obtusifoliaL.), and coffee senna (Cassia occidentalisL.).

Influence of fusaric acid on circadian leaf movements of the cotton plant, Gossypium hirsutum

The cotton plant, Gossypium hirsutum L. (cv. Lakshmi) exhibits circadian leaf movements. Fusaric acid (5-n butyl pyridine 2-carboxylic acid), an in vivo toxin shown to be produced during the pathogenesis of the wilt disease in cotton, causes phase shifts of the leaf movement rhythm that varied in degree and magnitude as a function of the treated phases. The data support the hypothesis that membranes play a vital role as a pacemaker in circadian rhythms.

Effects of cAMP, theophylline, imidazole, and 4-(3,4-dimethoxybenzyl)-2-imidazolidone on the leaf movement rhythm of Trifolium repens?a test of the cAMP-hypothesis of circadian rhythms

The period length of the leaf movement rhythm of Trifolium repens L. is lengthened by continuously offered cAMP (0.5-1.0 mol m(-3)) and theophylline (0.5-4 mol m(-3)). At the higher concentrations this effect is more pronounced and the rhythm damps out faster. Imidazole (0.5 and 1 mol m(-3)) has no effect on the period length; however, after 5 mol m(-3) the rhythm is abolished. Offered as 4 h pulses the resulting phase response curves for cAMP and imidazole are similar and show delays of up to 4 h during the day position of the leaves. Theophylline pulses lead to delays of up to 5 h during closure and advances of up to 3 h during opening. No phase shift is brought about by 4-(3,4-dimethoxybenzyl)-2-imidazolidone. The results do not support the cAMP-model of the circadian clock which has been proposed by Cummings (J. theor. Biol. 55, 455-470; 1975). The effect of the substances tested could, however, be based upon influences on the transport of Ca(2+).

Different circadian rhythms regulate photoperiodic flowering response and leaf movement in Pharbitis nil (L.) Choisy

The phase shifting effect of red light on both the leaf movement rhythm, and on the rhythm of responsiveness of photoperiodic flower induction towards short light breaks (10 min red light), has been studied in Pharbitis nil, strain Violet, and comparisons between the two rhythms have been made. The phase angle differences between the rhythms after a phase shift with 2 or 6 h of red light given at different times during a long dark period were not constant. The results indicate the involvement of two different clocks controlling leaf movement and photoperiodic flower induction.

Potassium-linked Chloride Fluxes during Rhythmic Leaf Movement of Albizzia julibrissin

Transverse sections of Albizzia pulvinules were examined with an electron microprobe to determine ion fluxes associated with turgorcontrolled leaflet movements. K(+) and Cl(-) concentrations are high in the flexor and low in the extensor region of closed pulvini. Both ions migrate out of the flexor and into the extensor during opening as previously described for K(+). The distribution of these elements is significantly correlated in each phase of the rhythmic cycle examined, but only 50 to 60% of the ionic charge of potassium is balanced by chloride. This value increases to 65 to 85% if one considers only the mobile fraction of the potassium.The increase in concentration of both ions in the extensor region precedes the decrease in the flexor, thus indicating that there must be a storage reservoir for K(+) and Cl(-). The inner cortex is suggested as such a reservoir, and plasmodesmata are discussed as a probable pathway for ion movement.

Phase Shifting Effect of Caffeine in the Circadian Rhythm of Phaseolus coccineus L

Abstract Caffeine, Circadian Rhythm, Sleep and Wakefulness, Phaseolus coccineus L. 4-hour caffeine pulses (10 mᴍ) offered via the trans­ piration stream advances or delays the phase of the circadian leaf movement rhythm of Phaseolus coccineus as a function of the phase of application. It is hypothesized that the caffeine effect upon sleep and wakefulness in man is partly due to this phase-shifting effect.

Photoperiodic Time Measurement and Circadian Leaf Movement in Pharbitis nil Controlled by the same Clock?

Summary Secondary leaves of 4 week old Pharbitis nil (L.) Choisy strain «Violet» plants show a circadian leaf movement rhythm, which can be entrained by light-dark cycles of 24 hours duration if the photofraction is longer than 4 hours and does not exceed 21.5 hours. The leaf movement rhythm undergoes phase shifts, if the plants are transferred to darkness at different times in the circadian cycle. Amount and direction of these phase shifts are determined by the time in the circadian cycle at which darkness begins. The amount of flower induction by a single 12 hour dark period depends, likewise, on the time in the circadian cycle at which it begins. Furthermore, the entraining and phase shifting effect of light on both - the leaf movement rhythm as well as the rhythm of the photoperiodic responsiveness of flower induction towards light breaks - have been studied and comparisons between the two are made. The phase angle difference between both rhythms is not constant, neither under entraining light conditions nor after phase shifting with a 6 hour red light break. This result possibly indicates the involvement of more than one circadian oscillator.

Periodenverlängerung und Phasenverschiebungen der circadianen Rhythmik von Phaseolus coccineus L. durch Theophyllin

Under the continuous influence of theophylline the period of the circadian leaf movement rhythm of Phaseolus is lengthened under conditions of continuous darkness and under conditions of continuous light. Four-h pulses of theophylline shift the rhythm as a function of the phase.It is hypothesized that these theophylline effects are based not upon inhibition of the phosphodiesterase which hydrolyses 3',5'-cAMP but on the influence on membrane function, particularly the transport and binding of Ca(2+).

The Participation of Two Rhythms in the Leaf Movements of Xanthium Plants Given Various Light-Dark Cycles

We have shown Xanthium strumarium exhibit two distinct leaf movement rhythms with one occurring in continuous light and presumably related to an endogenous rhythm initiated by the "light-on" signal and the other occurring in continuous dark and presumably related to an endogenous rhythm initiated by the "light-off" signal. Characteristic of the light-on rhythm is a sudden and rapid downward movement of the leaf occurring about 16 hours after the light-on signal. Characteristic of the light-off rhythm is an immediate and sudden upward movement following the light-off signal. Under certain photoperiodic treatments, the two movements seem to be in conflict.The characteristic light-on downward movement was predominant in the light-dark 14: 10 and 16: 8 treatments while the light-off upward movement was predominant in light-dark 8: 16 and 10: 14 treatments. In the light-dark 12: 12 treatment, one movement was predominant in about half of the cases and vice versa. Thus leaf movements of X. strumarium plants given these light-dark treatments were found to fit a hypothesis based on the participation of both a light-on and a light-off rhythm. The over-all leaf movement rhythm may be controlled by what might be called two clocks. Both of these clocks may have essentially the same basic mechanism with one important distinction. One is rephased by the light-on signal and the other by the light-off signal. Furthermore, the leaf movements related to each clock are distinctive.The hypothesis of the participation of a light-on and a light-off rhythm was also found to be applicable to published data (M. Holdsworth, 1959. Effects of day length on the movements of pulvinate leaves. New Phytol. 58: 29-45). Interpretation of the Bauhinia leaf movements along this line is also presented.

Rhythmic Leaf Movements in Biloxi Soybean and Their Relation to Flowering

The rhythmic leaf movement of Biloxi soybean (Glycine max) and its relationship to the rhythmic flowering response were studied. The movements of fully expanded trifoliate leaves were recorded with kymographs and time lapse photography in growth chambers. A comparison between the leaf movement rhythm and the rhythmic flowering response indicates that a high degree of similarity exists between the two rhythms. A definite relationship was shown to exist between the direction of the leaf movement and the photophil-photophobe phases of the rhythmic flowering response.Short light perturbations may affect flowering by interacting directly with the flowering process while not affecting the basic endogenous rhythm. Long light perturbations may affect flowering by phase shifting the basic endogenous rhythm. Thus, light perturbations appear to have a dual effect on the flowering response of Biloxi soybean. The hypothesis that both the flowering rhythm and the leaf movement rhythm are coupled to the same basic oscillator is supported by the similarity of the phase shifts induced in the two rhythms by identical light perturbations.

The internal clock of drunken isopods

Dilute solutions of ethyl alcohol lengthen the free-running period of the endogenous tidal rhythmicity of the isopod, Excirolana chiltoni. One-half percent alcohol increases the period, on the average, by about an hour, and the dosage dependence is apparently linear up to 1% alcohol. Since alcohol has also been shown to slow the circadian leaf-movement rhythm of the bean plant, Phaseolus, to about the same extent, the effects of this substance on endogenous biological clocks may represent a general phenomenon. Both this influence of alcohol, and previously reported effects of D2O on biological clocks are consistent with the hypothesis that the fundamental and general process underlying these endogenous rhythms involves an oscillation in cellular electrochemistry.

Circadian Rhythm of Leaves of Phaseolus angularis Plants Grown in a Controlled Carbon Dioxide and Humidity Environment

Leaf movements of primary leaves of Phaseolus angularis Wight. were studied in an environment with controlled levels of CO(2), relative humidity, temperature, light, nutrient concentrations, and water tension. Rhythmic circadian movements and irregular short period movements were evident as the leaves unfolded and persisted during development of the leaves. The mean period in rhythmic circadian movement was 27.3 hours with no significant differences in period between plants of the same or different experiments. The leaf movements of separate plants were not closely synchronized.A system is described for growing plants for extended periods while collecting data with time lapse photography. The system was developed to minimize disturbances to the plants.The occurrence of leaf movements in plants grown from the time of seeding in an environment free of any recognized fluctuation which could stimulate leaf movements supports the hypothesis that leaf movement rhythms originate spontaneously within the plant.

Photoelectric device for recording of leaf movements.

A photoeletric device is described that may have usefulness for sensing rhythmic leaf movements of plants in space experiments. The system provides an instantaneous record of the precise angular change in position of the leaf blade and avoids physical attachment or disturbance of the plant. This system has been utilized to record leaf movements for several weeks. The device is sufficiently sensitive to record small rapid oscillations by the leaf of only 2° angular movement.

Effects of Light Quality on the Circadian Rhythm of Leaf Movement of a Short-Day-Plant

Studies were made of the effects of blue, green, red and far-red (FR) light on the circadian rhythm of leaf movement of Coleus blumei x C. frederici, a short day plant. Under continuous illumination with blue light, there was a significant lengthening of the period of the rhythm to about 24.0 hr, as compared to 22.5 hr in continuous darkness. Under continuous red light, the period length was significantly shortened to 20.5 hr. Under continuous green or FR, the period length was not significantly different from the dark control. It was observed that under continuous FR illumination, the leaves tended to oscillate in a more downward position. Eight-hr red light signals were effective in advancing the phase of the rhythm as compared to a control under continuous green light. Blue light signals were effective in delaying the phase of the rhythm. FR light signals were ineffective in producing either delay or advance phase shifts. Far-red light did not reverse the effects of either red or blue light signals. On the basis of these results it is suggested, that pigments which absorb blue or red light, rather than phytochrome, mediate the effect of light on the circadian rhythm of leaf movement.

The Circadian Rhythm of Leaf Movement of Coleus blumei x C. frederici, a Short Day Plant. II. The Effects of Light and Temperature Signals

The phase response curve for the circadian rhythm of leaf movement of Coleus blumei x C. frederici, a short day plant, is generally similar to those reported for other organisms. An increase in the duration of the light signal caused an increase in the extreme values of the phase response curve and shortened the time for transition from maximum delays to maximum advances. Experiments with 2 light signals showed that the overt rhythm of leaf movement represents the rhythm of the light sensitive oscillator even during the transient period that followed the first light signal. A temperature decrease of 7 degrees for 8 hr caused only a transient phase shift in the following 2 cycles but not in the steady state. The combination of such a temperature decrease and a light signal showed that only the overt rhythm of leaf movement was disturbed by the temperature decrease whereas the light sensitive oscillator was free running. A temperature decrease of 11 degrees for 10 hr caused a steady state phase shift and affected the light sensitive oscillator as well.

The Circadian Rhythm of Leaf Movement of Coleus blumei x C. frederici, a Short Day Plant. I. Under Constant Light Conditions

A new instrument for the recording of leaf movement rhythm is described. Coleus blumei x C. frederici, a short day plant, exhibits a circadian rhythm of leaf movement. The period length of the free running rhythm is shortest in continuous darkness and is increased with an increase in the light intensity. The amplitude of the rhythm tends to damp in continuous bright light.

The Flowering Response of Coleus in Relation to Photoperiod and the Circadian Rhythm of Leaf Movement

The flowering response of Coleus frederici and Coleus blumei x C. frederici is dependent on the photoperiod; both plants have a critical day length of about 12 hr. The inductive phase, defined as the period when light signals inhibit floral development, started 10 hr after the onset of darkness under 4 and 8-hr photoperiods, and 8 hr after the onset of darkness under a 12-hr photoperiod. However, a fixed temporal relationship between the inductive phase and the minimum leaf position was observed for Coleus frederici. The inductive phase always started 5 hr after the minimum leaf position. This evidence supports the theory that a circadian clock participates in the time measurement process of photoperiodic floral induction.