Phytochrome control of the lag phase of chlorophyll accumulation in Lemna minor

1975 ◽  
Vol 53 (21) ◽  
pp. 2405-2410 ◽  
Author(s):  
Hugh Frick
Keyword(s):  
Lemna Minor ◽  
Red Light ◽  
Lag Phase ◽  
Chlorophyll Accumulation ◽  
Rapid Accumulation ◽  
Lag Period ◽  
Accumulation Phase ◽  
And Control ◽  
Etiolated Plants ◽  
Rate Of Accumulation

The 10- to 12-h lag phase in chlorophyll accumulation preceding the rapid accumulation phase in Lemna minor de-etiolating in the light was eliminated by a red light preillumination given about the length of the lag period before the onset of continuous red light. Neither the rate after the lag nor the extent of cholorophyll accumulation differed between preilluminated and control plants. Both the rate of accumulation in controls and the absolute stimulation by preillumination were shown to depend upon the length of time the etiolated plants had been grown in darkness up to 93 days. Only one photoproduct of preillumination contributed to the elimination of the chlorophyll lag phase, but the effect of red light was only partially (about 60%) nullified by subsequent far-red light.

Physiology and plastid fine structure of deetiolating Lemna minor

1976 ◽  
Vol 54 (15) ◽  
pp. 1819-1826 ◽  
Author(s):  
Hugh Frick ◽  
Raymond F. Jones
Keyword(s):  
Higher Plants ◽  
Lemna Minor ◽  
Red Light ◽  
Acid Synthesis ◽  
Light Illumination ◽  
Fresh Weight ◽  
Plastid Development ◽  
Prolamellar Bodies ◽  
Rate Of Increase ◽  
Etiolated Plants

During the 12-h lag period in chlorophyll accumulation after the onset of white-light illumination of Lemna minor etiolated for 35 days, a rapid increase in visible fronds per culture occurred. This new frond production then assumed a log-linear rate of increase, and total protein per unit fresh weight came to parallel the rate of increase in fresh weight per plant. The ribosomal RNA content of 45-day-etiolated plants was deficient in 23S and 16S species compared with green plants. The prolamellar bodies of etioplasts were either tightly or loosely paracrystalline within the same cell; they were without extended perforate lamellae, which developed during far-red-light illumination even while prolamellar bodies persisted. The development of chloroplasts in deetiolating L. minor was typical of other higher plants. The developmental sequence in green Lemna included proplastid to deeply stacked granal chloroplast within several millimetres. Plastid profiles suggestive of division configurations occurred only in primordial cells of green and etiolated plants. The relatively small numbers of plastids in any given stage of differentiation may account for the sensitivity of plastid development to inhibitors of protein and nucleic acid synthesis.

scholarly journals EARLY STAGES IN THE DEVELOPMENT OF PLASTID FINE STRUCTURE IN RED AND FAR-RED LIGHT

1964 ◽  
Vol 22 (2) ◽  
pp. 433-442 ◽  
Author(s):  
Shimon Klein ◽  
G. Bryan ◽  
Lawrence Bogorad
Keyword(s):  
Fine Structure ◽  
Stages Of Change ◽  
Structural Changes ◽  
Red Light ◽  
Prolamellar Body ◽  
Lag Phase ◽  
Prolamellar Bodies ◽  
Chlorophyll Accumulation ◽  
Time Required ◽  
Bean Leaves

Developmental changes in fine structure were studied in plastids of etiolated bean leaves during the time required for the protochlorophyllide-chlorophyllide transformation and the following lag phase prior to chlorophyll accumulation. In agreement with some other workers, two distinct stages of change in the fine structure of proplastids were found to occur upon illumination during this period. The first involves a dissociation of the previously fused units in the prolamellar bodies of the proplastids and occurs simultaneously with the protochlorophyllide-chlorophyllide conversion in light of 655 mµ, but not of 682, 700, or 730 mµ. The effect of the red light could not be reversed by a simultaneously supplied stronger far-red irradiation. The energy requirements for these structural changes parallel those for the pigment conversion. During the following step the vesicles which arose from the fused units of the prolamellar body were dispersed in rows through the stroma, and the prolamellar bodies themselves disappeared. For these changes to occur, higher light energies were required and the leaves had to be illuminated for longer periods. A red preillumination seemed to accelerate the development somewhat. The structural changes could be induced by light of 655 mµ, but also, to a lesser degree, of 730 mµ. No measurable additional chlorophyll accumulated during this period. Thus, the structural changes observed were independent of major changes in pigment content.

scholarly journals Photoselective Protective Netting Improves “Honeycrisp” Fruit Quality

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1708
Author(s):  
Sara Serra ◽  
Stefano Borghi ◽  
Giverson Mupambi ◽  
Hector Camargo-Alvarez ◽  
Desmond Layne ◽  
...  
Keyword(s):  
Fruit Quality ◽  
Scattered Light ◽  
Red Light ◽  
Light Transmittance ◽  
Light Spectrum ◽  
Growing Seasons ◽  
Color Development ◽  
Red Color ◽  
Bitter Pit ◽  
And Control

High temperatures, wind, and excessive sunlight can negatively impact yield and fruit quality in semi-arid apple production regions. Netting was originally designed for hail protection, but it can modify the light spectrum and affect fruit quality. Here, pearl, blue, and red photoselective netting (≈20% shading factor) was installed in 2015 over a commercial “Cameron Select® Honeycrisp” orchard. Our research objectives were to (1) describe the light quantity and quality under the colored nets compared to an uncovered control and (2) investigate the effect of Photoselective nets on “Honeycrisp” apple quality for two growing seasons. Light transmittance and scattering for each treatment were measured with a spectroradiometer, and samples for fruit quality analyses were collected at harvest. PAR (photosynthetic active radiation), UV, blue, red, and far-red light were lower underneath all netting treatments compared to an uncovered control. The scattered light was higher under the pearl net compared to other colors, while red and far-red light were lower under the blue net. For two consecutive years, trees grown under the photoselective nets intercepted more incoming light than the uncovered trees with no differences among the three colors. In both years, trees under red and blue nets had more sunburn-free (clean) apples than pearl and control. Red color development for fruit was lower when nets were used. Interestingly, bitter pit incidence was lower underneath red nets for both years. Other than red color development, “Honeycrisp” fruit quality was not appreciably affected by the use of netting. These results highlight the beneficial effect of nets in improving light quality in orchards and mitigating physiological disorders such as bitter pit in “Honeycrisp” apple.

Regulators of Cell Division in Plant Tissues. XXII* Physiological Aspects of Cytokinin-induced Radish Cotyledon Growth

1975 ◽  
Vol 2 (2) ◽  
pp. 129
Author(s):  
M.E Gordon ◽  
D.S Letham
Keyword(s):  
Translational Control ◽  
Total Protein ◽  
Specific Activity ◽  
Red Light ◽  
Growth Control ◽  
Growth Stimulation ◽  
Protein Levels ◽  
Dna And Rna ◽  
Dna And Rna Synthesis ◽  
Lag Period

The cytokinin 6-benzylaminopurine (BAP) markedly stimulated the lateral expansion of excised immature radish cotyledons after a lag period of about 10 h. This growth occurred principally by cell enlargement, especially in the light which enhanced the response. However, a marked response 'to cytokinin occurred in the complete absence of red light during germination, cotyledon excision and incubation. Contact with BAP for 5 h significantly stimulated growth, but a maximum response required more than 24 h of contact; potassium chloride also promoted cotyledon expansion and acted synergistically with cytokinin. The response to cytokinin did not appear to be mediated by ethylene, gibberellins, polyamines or cyclic nucleotides. Growth induction did not alter the respiration rate and appeared to be inde- pendent of chloroplast function. Inhibitors of DNA and RNA synthesis and of protein synthesis on cytoplasmic ribosomes almost completely abolished BAP-induced growth, control growth being less markedly affected. There were, however, no significant BAP-induced increases in total DNA or RNA levels or specific activity before the initiation of growth stimulation. Similarly, BAP had no effect on any individual RNA species until after the lag period, when there was a small enhancement of uridine incorporation into RNA species with similar electrophoretic mobility to rRNA. Although total protein levels were not affected by BAP, the cytokinin enhanced amino acid incorporation into protein within the lag period, an effect which persisted when transcription was strongly inhibited by actinomycin D. Phosphorylation of total protein was stimulated by BAP only well after the onset of cytokinin-induced growth. Protein methylation, however, was stimulated by BAP during the lag period, and the effect was at least as early as the BAP-enhanced incorporation of methionine into protein. The possible role of translational control in the mechanism of cytokinin action is discussed.

scholarly journals Analysis on Illegal Crossing Behavior of Pedestrians at Signalized Intersections Based on Bayesian Network

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Yingying Ma ◽  
Siyuan Lu ◽  
Yuanyuan Zhang
Keyword(s):  
Bayesian Network ◽  
Red Light ◽  
Signalized Intersections ◽  
Impact Factors ◽  
The Road ◽  
Illegal Behavior ◽  
Safety Countermeasures ◽  
Behavior Choice ◽  
And Control ◽  
Behavior Models

Pedestrians do not always comply with the crossing rules of when and/or where to cross the road at signalized intersections. This risky behavior tends to undermine greatly the effectiveness of safety countermeasures at such locations. Thus, it is very important to understand illegal behavior to develop more effective and targeting measures. In order to address the problem, this paper aimed to analyze characteristics of illegal crossings and their impact on behavior choice. Firstly, illegal crossing behaviors at signalized intersections were classified into two categories, including “crossing at a red light” and “crossing outside of a crosswalk.” Secondly, two sets of data were collected to understand the behaviors. One set of data was collected from video-based observation conducted at 3 signalized intersections in Guangzhou, China, capturing 3334 valid illegal crossing cases in total. Another set of data, from a questionnaire survey conducted online, resulted in 275 valid responses. Finally, presentational characteristics of illegal crossings at signalized intersection were analyzed and two Bayesian network-based behavior models were developed to investigate the characteristics and their impacts on the two types of illegal crossing behaviors, “crossing at a red light” and “crossing outside of a crosswalk,” respectively. Findings reveal that, (i) illegal crossings occur at various types of signalized intersections, with a higher probability for “crossing outside of a crosswalk” compared to “crossing at a red light;” (ii) Arc routing crossing has the highest probability to occur at signalized intersections compared to other types of out-side-crosswalk crossings. (iii) The location of origin and destination of a pedestrian has a significant effect on crossing outside of a crosswalk, the location of origin and destination of “one is inside of a crosswalk and another is outside of a crosswalk” has a highest proportion. These findings provide better understanding of illegal crossings and their impact factors so that the effectiveness of management and control of pedestrians at signalized intersections can be improved.

scholarly journals No effect of plant growth retarding compounds and growth stimulators on indolo-3-acetic acid oxidase activity in greening cucumber cotyledons

2015 ◽  
Vol 42 (3) ◽  
pp. 441-452 ◽  
Author(s):  
J. S. Knypl
Keyword(s):  
Oxidase Activity ◽  
Chlorophyll Synthesis ◽  
Lag Phase ◽  
Acid Oxidase ◽  
Iaa Oxidase ◽  
Crude Enzyme Extract ◽  
Chlorophyll Accumulation ◽  
Cucumber Cotyledons ◽  
Amo 1618 ◽  
Molecular Sieving

Cotyledons dissected from 5-day-old etiolated cucumber seedlings were incubated in solutions on AMO-1618, B-Nine, CCC and Phosfon D for 48 h in light. In some tests the retardants were applied in mixed solutions with GA<sub>3</sub> or BAP. IAA oxidase was extracted and purified by means of molecular sieving through a bed of Sephadex G-25. The retardants inhibited chlorophyll synthesis by 50 % or more, and had essentially no effect on IAA oxidase activity per cotyledon basis. GA<sub>3</sub> and BAP also had no effect on enzyme activity in spite of a fact that the compounds stimulated growth of the cotyledons. The crude enzyme extract from B-Nine treated cotyledons showed lower IAA oxidase activity in comparison with the water treated control, the effect being due to a longer lag-phase preceding the initiation of IAA oxidation. KNO<sub>3</sub> strikingly stimulated expansional growth of the cotyledons, the effect being correlated with the accelerated chlorophyll accumulation. KNO<sub>3</sub> had no effect on IAA oxidase activity per cotyledon and decreased it per gram fr wt. It is concluded that [1] the growth rate of cucumber cotyledons is not correlated with IAA oxidase activity, and ;[2] the growth retarding compounds do not affect IAA oxidase system is this tissue.

scholarly journals Modeling bus bunching and anti-bunching control accounting for signal control and passenger swapping behavior

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Qi Xin ◽  
Rui Fu ◽  
Shaowei Yu ◽  
Satish Ukkusuri ◽  
Rui Jiang
Keyword(s):  
Red Light ◽  
Propagation Model ◽  
Signalized Intersection ◽  
Driver Model ◽  
Average Speed ◽  
Extra Energy ◽  
Proposed Model ◽  
Bus Bunching ◽  
Finite State ◽  
And Control

The conventional bus propagation process has two main shortcomings: one is bus bunching, the other is extra energy consumption by idling at signalized intersection and unexpected speed variation along the route. To overcome these problems simultaneously, an extended bus propagation model and an anti-bunching control are proposed. To extend the time-based bus propagation model, we employ finite state machine and intelligent driver model to establish a spatial-temporal based bus propagation model accounting for bus dynamic motion and passenger swapping behavior between bunching buses. To mitigate bus bunching and improve bus fuel economy in a cyber-traffic environment, an anticipated average speed planning is employed to improve headway regularity and reduce the chance of encountering red light, and then model predictive control accounting for state and control constraints is used to generate a smooth speed trajectory for connected bus to follow the commands given by anticipated average speed planning, which will in turn ensure that all the connected buses traverse signalized intersection and approach downstream stop in ecological driving behaviors. Numerical simulations show that the proposed model can imitate passenger swapping behavior when bus bunching occurs, and the anti-bunching control is suitable to mitigate bus bunching and guide connected bus to traverse signalized intersection and reach downstream stop with fewer delays.

scholarly journals The Effects of Light Color on Seed Germination of Markhamia stipulata (Wall.) Seem

2017 ◽  
Vol 3 (4) ◽  
pp. 233
Author(s):  
Sri Ulie Rahmawati ◽  
Arief Noor Rachmadiyanto
Keyword(s):  
Seed Germination ◽  
Germination Rate ◽  
Block Design ◽  
Red Light ◽  
Botanical Garden ◽  
Dark Light ◽  
Significant Difference ◽  
Length Width ◽  
Light Color ◽  
And Control

<p class="Els-body-text"><em>Markhamia stipulata </em>(Wall.) Seem. (Bignoniaceae) is one of collections in Bogor Botanical Garden that potential as a medicine. Information about germination of these species were not known yet. This research was aimed to examine the effect of light color on germination process of <em>Markhamia stipulata</em> (Wall.) Seem. The research method used a Randomized Complete Block Design (RCBD) that consist of three treatments (red light, far red light, dark) and one control (open air) with four replications for each group. Each group consist of 10 seeds. Precentage of seed germination; seedling height; cotyledon width; length, width and number of leaves were measured. The result showed that seed germination start at third day after sowing.  Germination rate and germination rate coefficcient showed there is no significant difference between all treatments even though far red light showed highest number (100 %; 0.755).  However, light color influence on seedling growth. Far red light showed affect on internodes distance. Dark light showed affect on leaves and cotyledon size. Red light and control showed similarity.</p><p> </p><div><p class="Els-keywords"><strong>Keywords:</strong> dark; far red light<em>, </em><em>Markhamia stipulata</em> (Wall.) Seem; red light; seed germination</p></div>

scholarly journals Action Spectrum for the Opening of Albizia Julibrissin Pinnules, and the Role of Phytochrome in the Closing Movements of Pinnules and of Stomata of Vicla Faba

1972 ◽  
Vol 25 (5) ◽  
pp. 885 ◽  
Author(s):  
LT Evans ◽  
WG Allaway
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Action Spectrum ◽  
Leaf Age ◽  
Potassium Ions ◽  
Albizia Julibrissin ◽  
Action Spectra ◽  
Lag Period

The opening movements of both V. faha stomata and A. julibris8in pinnules have been shown previously to depend on a redistribution of potassium ions under the influence of light. Action spectra for both systems show peak effectiveness in blue light, at 440 nm, but for pinnule opening in A. julibri88in there is a subsidiary peak in the far red (720 nm). However, opening in far red shows an initial lag period, whereas opening in blue light is rapid. The action spectrum for pinnule opening was not influenced by leaf age, the presence or absence of CO2, or by simultaneous red light.

Sign in / Sign up

Export Citation Format

Share Document