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

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.

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Flowering in Pisum: Does Gibberellic Acid Directly Influence the Flowering Process?

Functional Plant Biology ◽

10.1071/pp9770479 ◽

1977 ◽

Vol 4 (4) ◽

pp. 479 ◽

Cited By ~ 3

Author(s):

JB Reid ◽

PJ Dalton ◽

IC Murfet

Keyword(s):

Gibberellic Acid ◽

Direct Effect ◽

Continuous Light ◽

Flower Initiation ◽

Small Delay ◽

Effect Of Age ◽

Flowering Process

Gibberellic acid is shown to cause a substantial delay in the flowering node, time of flower initiation and leaf requirement for flowering in the late pea cultivar line 24, grown under an 8-h photoperiod. In continuous light, gibberellic acid caused only a small delay in the flowering node and leaf require- ment. As the plants became older the effect of applied gibberellic acid decreased. This was not due to initiation having already occurred or to the gibberellic acid not penetrating the plant. It is suggested that gibberellic acid has a direct effect on the flowering process in line 24 plants grown under an 8-h photoperiod and that it may act by reducing the effect of age on the gene Sn.

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FLORAL INITIATION IN STRAWBERRY AND SOME EFFECTS OF RED AND FAR-RED RADIATION AS COMPONENTS OF CONTINUOUS WHITE LIGHT

Canadian Journal of Botany ◽

10.1139/b66-079 ◽

1966 ◽

Vol 44 (5) ◽

pp. 663-668 ◽

Cited By ~ 12

Author(s):

W. B. Collins

Keyword(s):

White Light ◽

Concentration Gradient ◽

Red Light ◽

Continuous Light ◽

High Energy ◽

Clear Distinction ◽

Flower Initiation ◽

Floral Initiation ◽

Mother Plants ◽

Red Radiation

The effects of different ratios of red to far-red radiation in continuous light on flower initiation in strawberry are described. A correlation was found between flower promotion and the content of far-red light in the supplied radiation which may be related to the red/far-red ratio of light and therefore to the level of phytochrome-Pfr in the plants. However, since relatively high energy (white) light was the only radiation used, a clear distinction between photosynthetic and red/far-red photoreversible effects is not possible. Flowering did not occur on all runner plants. Where flowering was promoted it invariably occurred first on the second- or third-formed runner plants on the stolon. Flowering was delayed on the proximal runner plants and never occurred on the mother plants. The results support the premise that a flower-inhibiting system was present along a concentration gradient in the runner.

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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

Canadian Journal of Botany ◽

10.1139/b73-194 ◽

1973 ◽

Vol 51 (8) ◽

pp. 1521-1528 ◽

Cited By ~ 30

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.

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Biochemical Interactions of Atrazine and Glyphosate in Soybean (Glycine max) Seedlings

Weed Science ◽

10.1017/s0043174500072295 ◽

1989 ◽

Vol 37 (4) ◽

pp. 491-497 ◽

Cited By ~ 7

Author(s):

Robert E Hoagland

Keyword(s):

Chlorophyll Content ◽

Time Course ◽

Continuous Light ◽

Hypocotyl Elongation ◽

Anthocyanin Content ◽

Soybean Seedlings ◽

Atrazine Treatment ◽

Mathematical Analyses ◽

Molecular Mode ◽

Nr Activity

Laboratory studies were conducted to evaluate possible interactions of atrazine and glyphosate on soybeans at the molecular level. Because these compounds alter the extractable activities of nitrate reductase (NR)3and phenylalanine ammonia-lyase (PAL), these enzymes were chosen as biochemical markers. Levels of anthocyanin, hydroxyphenolic compounds, and chlorophyll were also determined. Three-day-old dark-grown soybean seedlings, susceptible to both herbicides, were transferred to 2 mM CaSO4or CaSO4containing high-purity 10–4M atrazine, 10–4M glyphosate, or a combination of both herbicides at 10–4M each. Plants were placed in a growth chamber under continuous light (200 μE·m–2·s–1) at 25 C and harvested at 24-h intervals over a 96-h time course. Interactions of atrazine and glyphosate on hypocotyl elongation were detected after 96 h when the compounds were supplied simultaneously. Intermediate PAL levels were found in the atrazine + glyphosate treatment compared to the levels for each herbicide alone. At 96 h, anthocyanin content in hypocotyls in the atrazine + glyphosate treatment was twice that of the atrazine treatment, and hydroxyphenolic content was increased by 25% (per axis). Interactions of these herbicides were also apparent on NR activity; i.e., on a per organ basis the combination treatment resulted in levels 20% higher than glyphosate alone in roots and 16 times greater than glyphosate alone in leaves after 96 h. Total chlorophyll content in hypocotyls (μg/organ) was decreased by atrazine but not significantly by glyphosate after 96 h. Atrazine + glyphosate resulted in chlorophyll content equal to that of atrazine alone. Mathematical analyses showed that interactions on NR, PAL, anthocyanin levels, and hypocotyl elongation were antagonistic at 96 h. These data demonstrate interaction between atrazine and glyphosate in plant tissues that is related to some biochemical parameters associated with the secondary molecular mode of action of these herbicides.

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

Canadian Journal of Botany ◽

10.1139/b65-092 ◽

1965 ◽

Vol 43 (7) ◽

pp. 825-853 ◽

Cited By ~ 59

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.

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Morphogenesis, pigment content, phytohormones and productivity of sweet pepper under the action of gibberellin and tebuconazole

Regulatory Mechanisms in Biosystems ◽

10.15421/022139 ◽

2021 ◽

Vol 12 (2) ◽

pp. 294-300

Author(s):

V. V. Rogach ◽

V. G. Kuryata ◽

I. V. Kosakivska ◽

L. V. Voitenko ◽

M. M. Shcherbatiuk ◽

...

Keyword(s):

Gibberellic Acid ◽

Chlorophyll Content ◽

Growth Regulators ◽

Treatment Plant ◽

Sweet Pepper ◽

Sand Culture ◽

Cultivated Plants ◽

Average Weight ◽

Endogenous Phytohormones ◽

Pepper Plants

One of the main tasks of modern plant physiology is regulation of growth and development of cultivated plants in order to optimize the productive process. The attention of the scientific community is focused on the use of natural activators and growth inhibitors. We investigated the effect of foliar treatment with 0.005% solution of gibberellic acid (GA3) and 0.025% solution of the antigibberellic preparation tebuconazole (EW-250) on morphogenesis, leaf mesostructure, the content of photosynthetic pigments, the balance of endogenous phytohormones and productivity of Capsicum annuum L., Antey variety. The vegetation experiment was carried out in the conditions of soil-sand culture in vessels with a volume of 10 L. Treatment of plants was carried out in the budding phase. Morphometric parameters were determined every 10 days. The mesostructure of the middle tier leaves was studied in the fruit formation phase, and the chlorophyll content was determined in the raw material by spectrophotometric method. Analytical determination of endogenous phytohormones – indolyl-3-acetic (IAA), gibberellic (GA3) and abscisic (ABA) acids and cytokinins – zeatin (Z), zeatin-O-glucoside (ZG), zeatinribozide (ZR), isopentenyladenine (iP) and isopentenyladenosine (iPA) were performed by high performance liquid chromatography – mass spectrometry (HPLC-MS). With GA3 treatment, plant height increased considerably, while with EW-250, it decreased. Both regulators led to an increase in the number of leaves on the plant, the leaf raw biomass, stems and roots and the dry matter of the whole plant, the area of a single leaf blade and the total area of leaves on the plant. Under the action of EW-250, the chlorophyll content in the leaves surged, while under the action of GA3 it tended to decrease or did not change at all. Both regulators thickened the chlorenchyma and boosted the volume of the columnar parenchyma cells. GA3 treatment induced a rise in the thickness of the upper and lower epidermis, and EW-250 led, on the contrary, to a decrease. It is shown that after treatment with exogenous GA3, the content of endogenous IAA and ABA decreased and GA3 in plant stems increased. Instead, EW-250 caused a decrease in the levels of GA3, IAA and ABA in the stems. Exogenous GA3 enhanced the accumulation of endogenous GA3 and IAA and inhibited ABA in the leaves. Under the action of the retardant, the level of ABA in the leaves did not change, while GA3 and IAA decreased. Treatment of plants with the studied growth regulators caused a decrease in the pool of cytokinins (CK) in stems. EW-250 showed a significant rise in the hormone content in the leaves. After spraying with GA3 solution, the level of ZG, Z and ZR grew. Under the action of the retardant, the increase in the CK pool occurred exclusively due to the iP. Growth regulators optimized the productivity of sweet pepper plants: under the action of GA3 there was an increase in the number of fruits per plant, and after the use of EW-250 there was a rise in the average weight of one fruit. The obtained results showed that anatomical-morphological and structural-functional rearrangements of sweet pepper plants under the action of exogenous gibberellic acid and EW-250 took place against the background of changes in the balance and distribution of endogenous hormones. Increased photosynthetic activity, stimulation of growth processes of some plant organs and inhibition of others enlarged biological productivity of the culture.

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