RHYTHMIC FLOWERING RESPONSES AND PHYTOCHROME CHANGES IN A SELECTION OF CHENOPODIUM RUBRUM

1965 ◽  
Vol 43 (7) ◽  
pp. 825-853 ◽  
Author(s):  
Bruce G. Cumming ◽  
Sterling B. Hendricks ◽  
H. A. Borthwick
Keyword(s):  
Dark Period ◽  
Continuous Light ◽  
Endogenous Rhythm ◽  
Chenopodium Rubrum ◽  
Flowering Response ◽  
Initial Substrate ◽  
Endogenous Circadian Rhythm ◽  
Light Darkness ◽  
Rhythmic Change

Flowering of Chenopodium rubrum L., selection 374, was examined with respect to an endogenous circadian rhythm, the state of phytochrome, and the result of changing the form of phytochrome during a single dark period of 2 to 96 hours interrupting continuous light. Darkness was imposed either 4 or 5 days after seeds were placed on moist filter paper in Petri dishes.The following working hypothesis, which is partly retrospective, is projected to explain the main features of the experimental results. Flowering is controlled by a product of the enzymatic action of the far-red absorbing form of phytochrome (Pfr) on a single but unknown substrate. In acting, Pfr finally reverts to the inactive red-absorbing form of phytochrome (Pr) or is changed from the Pfr form in some other way. The available substrate, if not utilized by Pfr action, is soon depleted by other reactions. The substrate for Pfr action is low during the skotophile but high during the photophile phases. The significant time for phasing is the beginning of darkness. The initial substrate supply appears to be derived from the preceding light period but some time in the region of the 9th to 12th hour of darkness a significant rhythmic change of substrate starts up. The dependence of flowering on the time that darkness is interrupted by light is directly related to a rhythmic change in the optimum Pfr level required for the processes leading to flowering.The role of the endogenous rhythm in flowering under natural conditions is questioned. Similarities that are shown in the control of flowering, whether the display is governed by an endogenous rhythm or by a daily photoperiodic cycle, indicate that phytochrome acts as a "pacemaker". It is suggested that the distinct ecotypic populations of C. rubrum that differ in flowering response have dissimilar levels and rates of supply of substrate for phytochrome action. In C. rubrum-374, complete reversion or loss of Pfr does not occur during a long dark period of 72 hours at 20 °C, but Pfr does decrease to low levels.A hydrodynamic system is discussed as an analogy to rhythmic flowering response.

Betacyanin accumulation, chlorophyll content, and flower initiation in Chenopodium rubrum as related to endogenous rhythmicity and phytochrome action

1970 ◽  
Vol 48 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Edgar Wagner ◽  
Bruce G. Cumming
Keyword(s):  
Gibberellic Acid ◽  
Chlorophyll Content ◽  
Dark Period ◽  
Continuous Light ◽  
High Energy ◽  
Hypocotyl Elongation ◽  
Chenopodium Rubrum ◽  
Physiological Status ◽  
Flower Initiation ◽  
Endogenous Rhythmicity

In Chenopodium rubrum seedlings (ecotypes 50°10′ N and 49°58′ N) betacyanin synthesis is light dependent (completely dark-grown seedlings contain no betacyanin) and is under phytochrome control via both the low energy and the high-energy (HER) reactions of photomorphogenesis. In continuous light, accumulation of betacyanin is linear with time. However, when a single dark period interrupts continuous light, the amount of both betacyanin and chlorophyll synthesized during a given period of time after the dark interruption shows a rhythm reflecting differences in the rate of, and (or) the capacity for, pigment accumulation that are dependent on the duration of the dark period. The rhythm in chlorophyll content was higher in frequency than circadian, with a period of about 15 h, while rhythmicity in the rate of synthesis of betacyanin was circadian. These results suggest that there is endogenous rhythmicity in the metabolic state of the system in darkness. The imposition of light after darkness apparently stabilizes the specific physiological status attained at that respective time of darkness and thus determines the metabolic activity of the seedlings.When glucose was supplied throughout darkness interrupting continuous light, the phasing of the rhythm of betacyanin synthesis was positively correlated with the rhythm of flower initiation, but this was not so when phenylalanine was supplied during darkness. In contrast, when glucose was supplied for a varied length of time in continuous light, there was rhythmicity in the rate of betacyanin accumulation, with a periodicity of about 15 h, that was dependent on the duration of the glucose application.When seedlings were supplied with 10−6 M gibberellic acid during darkness there was a rhythm in the amount of hypocotyl elongation that depended on the length of a single dark period interrupting continuous light. Other evidence has suggested that there is a rhythm in the stability of the cellular membranes; this rhythm was assayed (non-physiologically) by the time of onset of betacyanin leakage from seedlings into an extraction medium and was apparent only after application of 10−10 M gibberellic acid. The rhythms in hypocotyl elongation and in membrane stability that were revealed after the application of gibberellic acid suggest that there may be a rhythm in the rate of differentiation and (or) development of the system.It is postulated that endogenous rhythmicity is due to the spatial separation of energy production and use in different cell particulates, with phytochrome acting as a membrane operator.

scholarly journals DOES CHRYSANTHEMUM DISPLAY AN ENDOGENOUS CIRCADIAN RHYTHM OF STEM ELONGATION?

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1077f-1077
Author(s):  
Jason Tutty ◽  
Peter Hicklenton
Keyword(s):  
Circadian Rhythm ◽  
Constant Temperature ◽  
Dark Period ◽  
Stem Elongation ◽  
Continuous Light ◽  
Linear Displacement ◽  
Dendranthema Grandiflora ◽  
Diurnal Cycles ◽  
Diurnal Patterns ◽  
Endogenous Circadian Rhythm

The rate of internodal extension of chrysanthemum (Dendranthema grandiflora Tzvelev. cv. Envy) under various temperature and photoperiod conditions was studied to determine whether reproducible diurnal patterns of growth existed and whether any such patterns conformed to an endogenous circadian rhythm. Stem growth was monitored continuously by means of linear displacement voltage transducers. At constant temperature and under 11 h light/13 h dark photoperiod, stem elongation followed a clearly defined pattern consisting of a peak in rate immediately after the dark to light transition and then a gradual decline until the start of the dark period. During darkness, elongation rate increased and reached a maximum approximately 8 hours after the light to dark transition. This pattern differed when light period temperature was either above or below dark period temperature, but these patterns were also highly reproducible. When plants were subjected to continuous light at constant temperature, the rhythm of stem elongation initially showed a periodicity of approximately 27 hours. After 2 or 3 diurnal cycles the rhythm was less distinct and the rate became essentially constant. Furthermore, the interruption of a long period of continuous light with a 13 h dark period did not restore the rhythm. These findings do not support the existence of an endogenous circadian rhythm of stem elongation. Diurnally-cued rhythms do, however, exist and can be modified by temperature.

Phytochrome Action in the Induction of Plowering in Short-day Plants: Effect of Photoperiod Quality

1974 ◽  
Vol 1 (3) ◽  
pp. 445 ◽  
Author(s):  
RW King
Keyword(s):  
Photosynthetic Pigments ◽  
Prolonged Exposure ◽  
Dark Period ◽  
Red Light ◽  
Spectral Composition ◽  
Chenopodium Rubrum ◽  
Fluorescent Light ◽  
Flowering Response ◽  
Short Day ◽  
Red Radiation

Seedlings of Phavbitis nil and Chenopodium rubrum flower in response to a single inductive dark period preceded and followed by continuous fluorescent light. However, when a far-red irradiation for 1 h or longer was substituted for fluorescent light, the flowering response to an ensuing dark period could be completely inhibited or enhanced up to threefold depending on when the far-red exposure commenced. Evidence of red/far-red photoreversibility established phytochrome as the photoreceptor controlling these responses. There was no indication of the involvement of photosynthetic pigments. For P. nil prolonged exposure (1.5-6 h) to far-red radiation during the photoperiod could shorten (2-3 h) or lengthen (2 h) the duration of darkness required for flowering. The degree of change depended on whether the far-red radiation was imposed just prior to darkness (shortening) or about 9 h prior to darkness (lengthening). In a similar manner the spectral composition of the photoperiod influenced the timing during darkness for earliest sensitivity to brief (5 min) red light interruptions. The shorter the critical dark period, the earlier in darkness the seedlings became sensitive to red light interruptions of darkness. It is clear that the form of phytochrome during the photoperiod influences the timing of phytochrome- linked processes in darkness. Two explanations discussed are a coupling via rhythmic changes in substrate on which phytochrome acts, and an effect on phytochrome reactions which alters the timing of Pf, disappearance during a subsequent dark period.

Semidian rhythmicity in the flowering response of Pharbitis nil to changes in temperature

1998 ◽  
Vol 25 (2) ◽  
pp. 183 ◽  
Author(s):  
O.M. Heide ◽  
R.W. King ◽  
L.T Evans
Keyword(s):  
Circadian Rhythm ◽  
Constant Temperature ◽  
Opposite Effect ◽  
Dark Period ◽  
Floral Induction ◽  
Continuous Light ◽  
The Other ◽  
Pharbitis Nil ◽  
Flowering Response ◽  
Short Day

Our earlier experiments on flowering in the short day plant Pharbitis nil involved far- red/dark (FR/D) interruptions of 90 min duration at various times during a continuous light, constant temperature period before a single inductive dark period. They revealed a rhythm with a period of 12 h, hence semidian. We concluded that the phasing of this semidian rhythm determined the length of darkness required for floral induction. This conclusion has since been challenged so we sought other pretreatments which reveal the semidian rhythm. Interruptions at 12°C–17°C for 45–90 min at various times prior to the inductive dark period were as effective as FR/D in eliciting the semidian rhythm, with significant effects on flowering persisting for at least three cycles in constant conditions in continuous light. The rhythmic response to 12°C pretreatments was 3 h out of phase with that to FR/D pretreatments. Flowering responses to the semidian rhythm exposed by 12°C pretreatments were additive to and independent of those to a circadian rhythm. Some evidence was obtained of reversal of the inhibition or promotion of flowering by FR/D or 12°C by exposure immediately afterwards to the other pretreatment at times of their opposite effect. Pretreatments at 12°C, like those with FR/D, either reduced (if promotive) or extended (if inhibitory) the length of the dark period required for floral induction in this short day plant.

Endogenous rhythmicity and energy transduction. II. Phytochrome action and the conditioning of rhythmicity of adenylate kinase, NAD- and NADP-linked glyceraldehyde-3-phosphate dehydrogenase in Chenopodium rubrum by temperature and light intensity cycles during germination

1973 ◽  
Vol 51 (8) ◽  
pp. 1521-1528 ◽  
Author(s):  
Silvia Frosch ◽  
Edgar Wagner
Keyword(s):  
Light Intensity ◽  
Adenylate Kinase ◽  
Dark Period ◽  
Energy Transduction ◽  
Endogenous Rhythm ◽  
Chenopodium Rubrum ◽  
Germination Period ◽  
Endogenous Rhythmicity ◽  
Free Running

Endogenous rhythmicity in NADP- and NAD-linked glyceraldehyde-3-phosphate dehydrogenase (NADP- and NAD-GPD) as well as in adenylate kinase (AK) activity is initiated or synchronized during cyclic germination conditions of light and temperature, and is free-running in a dark period interrupting continuous light.There is phytochrome control of the amplitude in NADP-GPD and AK oscillations during the first hours of darkness if the beginning of the dark period is in phase with the beginning of the germination period. The endogenous rhythm acts like an "on-off" switch for potential phytochrome action. The results are discussed in relation to daily photoperiodic cycles.

CIRCADIAN RHYTHMIC FLOWERING RESPONSES IN CHENOPODIUM RUBRUM: EFFECTS OF GLUCOSE AND SUCROSE

1967 ◽  
Vol 45 (11) ◽  
pp. 2173-2193 ◽  
Author(s):  
Bruce G. Cumming
Keyword(s):  
Continuous Light ◽  
Light Period ◽  
Chenopodium Rubrum ◽  
Measuring System ◽  
Inhibitory Effects ◽  
Measuring Time ◽  
Natural Conditions ◽  
Similar Time ◽  
Endogenous Circadian Rhythm ◽  
Free Running

An endogenous circadian rhythm of flower induction in Chenopodium rubrum that depends on the length of darkness interrupting continuous light has a smaller amplitude and damps out earlier when the light preceding and (or) following darkness is limited in intensity. Glucose or sucrose, fed to plants throughout darkness, can enhance and sustain the rhythm over a considerably longer period. Some degree of specificity of glucose in the rhythmic process was indicated because, when this energy source was applied during a skotophile phase of darkness (particularly the first 9 h) there were inhibitory effects on the rhythmic flowering response, but the same concentration of glucose was stimulatory when applied during the photophile phase(s) of darkness. No similar time dependence resulted from sucrose treatments. To account for the effects of glucose in particular, it is postulated that endogenous sugar formation in the light period is involved in providing substrate for phytochrome-Pfr action or mediation during darkness. Damping out of the oscillation in extended dark periods is a consequence of depletion of sugar reserves during darkness. These and other results support the concept that Pfr acts as a pacemaker or valve and exerts some control over sugar availability and utilization. Comparisons involving the application of glucose to different ecotypes suggest that, for optimal induction, some definite balance is required between the endogenous availability of glucose, or some other sugar derivative(s), and the level of phytochrome Pfr; this balance apparently differs according to genotype.Differences between ecotypes in their rhythmic flowering responses suggest that the endogenous free-running clock is an integral part of the time-measuring system in daily photoperiodic cycles and that it does have a role in measuring time under natural conditions.

scholarly journals DOES CHRYSANTHEMUM DISPLAY AN ENDOGENOUS CIRCADIAN RHYTHM OF STEM ELONGATION?

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1077F-1077
Author(s):  
Jason Tutty ◽  
Peter Hicklenton
Keyword(s):  
Circadian Rhythm ◽  
Constant Temperature ◽  
Dark Period ◽  
Stem Elongation ◽  
Continuous Light ◽  
Linear Displacement ◽  
Dendranthema Grandiflora ◽  
Diurnal Cycles ◽  
Diurnal Patterns ◽  
Endogenous Circadian Rhythm

The rate of internodal extension of chrysanthemum (Dendranthema grandiflora Tzvelev. cv. Envy) under various temperature and photoperiod conditions was studied to determine whether reproducible diurnal patterns of growth existed and whether any such patterns conformed to an endogenous circadian rhythm. Stem growth was monitored continuously by means of linear displacement voltage transducers. At constant temperature and under 11 h light/13 h dark photoperiod, stem elongation followed a clearly defined pattern consisting of a peak in rate immediately after the dark to light transition and then a gradual decline until the start of the dark period. During darkness, elongation rate increased and reached a maximum approximately 8 hours after the light to dark transition. This pattern differed when light period temperature was either above or below dark period temperature, but these patterns were also highly reproducible. When plants were subjected to continuous light at constant temperature, the rhythm of stem elongation initially showed a periodicity of approximately 27 hours. After 2 or 3 diurnal cycles the rhythm was less distinct and the rate became essentially constant. Furthermore, the interruption of a long period of continuous light with a 13 h dark period did not restore the rhythm. These findings do not support the existence of an endogenous circadian rhythm of stem elongation. Diurnally-cued rhythms do, however, exist and can be modified by temperature.

Studies on the flowering biology of red sorrel (Rumex acetosella) ramets from lowbush blueberry (Vaccinium angustifolium) fields in Nova Scotia, Canada

Botany ◽  
2015 ◽  
Vol 93 (1) ◽  
pp. 41-46 ◽  
Author(s):  
Scott N. White ◽  
Nathan S. Boyd ◽  
Rene C. Van Acker ◽  
Clarence J. Swanton
Keyword(s):  
Nova Scotia ◽  
Combined Effects ◽  
Perennial Species ◽  
Weed Species ◽  
Vaccinium Angustifolium ◽  
Perennial Weed ◽  
Flowering Response ◽  
Lowbush Blueberry ◽  
Rumex Acetosella

Red sorrel (Rumex acetosella L.) is a ramet-producing herbaceous creeping perennial species commonly found as a weed in commercially managed lowbush blueberry (Vaccinium angustifolium Aiton) fields in Nova Scotia, Canada. Flowering and seed production occur primarily in overwintering ramets of this species, indicating a potential vernalization requirement for flowering. This study was therefore initiated to examine the role of vernalization, photoperiod, and pre-vernalization stimulus on ramet flowering. Red sorrel ramets propagated from creeping roots and seeds collected from established red sorrel populations in lowbush blueberry had an obligate requirement for vernalization to flower. Ramet populations maintained under pre- and post-vernalization photoperiods of 16 h flowered following 12 weeks of vernalization at 4 ± 0.1 °C, whereas those maintained under constant 16, 14, or 8 h photoperiods without vernalization did not flower. Vernalization for 10 weeks maximized, but did not saturate, the flowering response. Pre-vernalization photoperiod affected flowering response, with increased flowering frequency observed in ramet populations exposed to decreasing, rather than constant, photoperiod prior to vernalization. This study represents the first attempt to determine the combined effects of vernalization and photoperiod on red sorrel flowering, and the results provide a benchmark for the future study of flowering and sexual reproduction in this economically important perennial weed species.

The role of photoperiod and temperature in the induction and termination of an arrested development in two species of freshwater cyclopia copepods

1971 ◽  
Vol 49 (6) ◽  
pp. 855-862 ◽  
Author(s):  
Nelson H. F. Watson ◽  
B. N. Smallman
Keyword(s):  
Continuous Light ◽  
Temporary Pond ◽  
Environmental Cues ◽  
Complete Darkness ◽  
Arrested Development ◽  
Short Day ◽  
Long Day ◽  
Critical Daylength ◽  
Ecological Implications

Daylength and temperature were shown to be environmental cues which interact to cause an arrest in development at the fourth copepodite instar of two cohabiting, temporary pond species of the genus Diacyclops; D. navus Herrick, and a second species of uncertain specific designation. The first species entered arrest under short-day conditions, the latter under long days. Arrest did not occur in rearings conducted in either continuous light or complete darkness. Cyclopids were sensitive to the photoperiodic stimulus only during the first copepodite instar. Temperature was shown to affect the critical daylength values associated with a transition from a long-day to a short-day response for each species.Similarities with insect diapause and the ecological implications of the response are discussed.

Sign in / Sign up

Export Citation Format

Share Document