The Behaviour of Shoot Apices of Lolium temulentum in vitro as the Basis of an Assay System for Florigenic Extracts

1993 ◽  
Vol 20 (3) ◽  
pp. 337 ◽  
Author(s):  
RW King ◽  
C Blundell ◽  
LT Evans
Keyword(s):  
Gibberellic Acid ◽  
Growth Medium ◽  
High Irradiance ◽  
Plant Age ◽  
Assay System ◽  
Shoot Apices ◽  
Long Day ◽  
Intact Plants ◽  
Short Days

Previous experiments have shown that shoot apices excised from plants of L. temulentum that had been exposed to one long day (LD) could form inflorescence primordia in vitro if gibberellic acid (GA3) was present in the medium whereas apices from plants in short days (SD) could not. We show here that apices from older plants grown under high irradiance can undergo inflorescence differentiation in vitro after one LD even in the absence of GA3, as can apices from plants in SD if GA3 is present in the medium. For apices excised from both SD and one LD plants, the order of effectiveness of gibberellins for inflorescence induction was 2,2-dimethyl GA4 > GA5 > GA3 > GA1, in agreement with their ranking for effectiveness on intact plants. Application of GA3 to leaves before apex excision can substitute for GA3 in the growth medium. The presence of GA3 in the medium is not required until 4-6 days after excision from plants given one LD, and appears to be necessary for differentiation beyond the spikelet primordia stage. Three hypotheses concerning the relation between GAs and the LD stimulus to flowering, as affected by plant age, are considered.

scholarly journals Gibberellic acid flower formation and stem elongation in Silene armeria.

1973 ◽  
Vol 21 (4) ◽  
pp. 245-255
Author(s):  
S.J. Wellensiek
Keyword(s):  
Gibberellic Acid ◽  
Stem Elongation ◽  
Flowering Plants ◽  
Plant Age ◽  
Flower Formation ◽  
High Concentration ◽  
Short Day ◽  
Long Day ◽  
Silene Armeria

Several selected S. armeria lines differing in their reaction to GA3 were treated with GA3 at various concentrations under short-day (SD) or long-day conditions. With SD treatment one application of GA3 at high concentration (10 000 p.p.m. or greater) induced flower formation in certain lines. Stem elongation increased with GA3 concentration and with plant age and was much greater on flowering plants than on non-flowering ones. [For previous related work see HcA 41, 4400.]. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Photoperiod modulates the effects of norepinephrine on lymphocyte proliferation in Siberian hamsters

2003 ◽  
Vol 285 (4) ◽  
pp. R873-R879 ◽  
Author(s):  
Gregory E. Demas ◽  
Timothy J. Bartness ◽  
Randy J. Nelson ◽  
Deborah L. Drazen
Keyword(s):  
Lymphocyte Proliferation ◽  
Splenic Tissue ◽  
Splenocyte Proliferation ◽  
Short Day ◽  
Siberian Hamsters ◽  
Long Day ◽  
Β Adrenergic Receptors ◽  
Short Days

Siberian hamsters ( Phodopus sungorus) rely on photoperiod to coordinate seasonally appropriate changes in physiology, including immune function. Immunity is regulated, in part, by the sympathetic nervous system (SNS), although the precise role of the SNS in regulating photoperiodic changes in immunity remains unspecified. The goal of the present study was to examine the contributions of norepinephrine (NE), the predominant neurotransmitter of the SNS, to photoperiodic changes in lymphocyte proliferation. In experiment 1, animals were maintained in long [16:8-h light-dark cycle (16:8 LD)] or short days (8:16 LD) for 10 wk, and splenic NE content was determined. In experiment 2, in vitro splenocyte proliferation in response to mitogenic stimulation (concanavalin A) was assessed in spleen cell suspensions taken from long- or short-day hamsters in which varying concentrations of NE were added to the cultures. In experiment 3, splenocyte proliferation was examined in the presence of NE and selective α- and β-noradrenergic receptor antagonists (phenoxybenzamine and propranolol, respectively) in vitro. Short-day animals had increased splenic NE content compared with long-day animals. Long-day animals had higher proliferation compared with short-day animals independent of NE. NE (1 μM) further suppressed splenocyte proliferation in short but not long days. Last, NE-induced suppression of proliferation in short-day hamsters was blocked by propranolol but not phenoxybenzamine. The present results suggest that NE plays a role in photoperiodic changes in lymphocyte proliferation. Additionally, the data suggest that the effects of NE on proliferation are specific to activation of β-adrenergic receptors located on splenic tissue. Collectively, these results provide further support that photoperiodic changes in immunity are influenced by changes in SNS activity.

Short Day Induction of Inflorescence Initiation in Some Winter Wheat Varieties

1987 ◽  
Vol 14 (3) ◽  
pp. 277 ◽  
Author(s):  
LT Evans
Keyword(s):  
Winter Wheat ◽  
High Irradiance ◽  
Inflorescence Development ◽  
Wheat Varieties ◽  
Short Day ◽  
Long Day ◽  
European Winter Wheat ◽  
Lower Irradiance ◽  
Short Days ◽  
Winter Wheat Varieties

Experiments in the Canberra phytotron with several European winter wheat varieties, especially cv. Templar, have shown that their need for vernalisation at low temperature can be replaced entirely by growth in short days at 21/16°C for the same period. In fact, although wheat is usually classified as a long day plant, inflorescence initiation at 21/16°C in unvernalised plants was twice as rapid in 8 h photoperiods as in 16 h ones. Short day induction was fastest in photoperiods of less than 12 h and was relatively insensitive to irradiance. Inflorescence development following initiation was faster the longer the photoperiod. At high irradiance, anthesis eventually occurred in 8 h days, but not at lower irradiance. These wheats are therefore short-long day plants, and may appear to be indifferent to daylength if only their time to anthesis is observed. Although short days can replace low temperatures, there are several important differences in their modes of action, and short day induction is better not referred to as short day vernalisation. Vernalisation of developing grains in the ear was more effective in long days.

The Role of Photosynthesis in Flowering of the Long-Day Plant Sinapis alba

1977 ◽  
Vol 4 (4) ◽  
pp. 467 ◽  
Author(s):  
M Bodson ◽  
RW King ◽  
LT Evans ◽  
G Bernier
Keyword(s):  
Sinapis Alba ◽  
High Irradiance ◽  
Atmospheric Co2 ◽  
Co2 Uptake ◽  
Long Day ◽  
Absolute Requirement ◽  
Full Flowering ◽  
Lower Irradiance ◽  
Short Days

Flowering can be induced in the long-day plant Sinapis alba in 8-h photoperiods provided that the irradiance is close to that at which leaf photosynthesis is light-saturated (e.g. 96 J m-2 s-1). Three such 8-h cycles result in 10% flowering and six are required for full flowering, whereas only one long-day cycle of 16-20 h duration at a much lower irradiance (25 J m-2 s-1) is required for full flowering. High irradiance during the single long day promotes flowering when given for the first 8 h of a 16-h photoperiod, but is inhibitory over the last 8 h. Photosynthetic CO2 uptake is crucial for this response to high irradiance, as both its inhibitory and promotive effects on flowering are reversed by the removal of atmospheric CO2 during the period of high irradiance. Compared with plants kept in short days (8-h photoperiod), export of 14C-labelled assimilates from the leaf during a 24-h period was only 50-60% greater in plants exposed to a long day (20-h photoperiod), because plants in short days compensated to a degree for their shorter photosynthetic period by mobilizing leaf reserves during darkness. However, flowering can occur with no evident enhancement of supply of assimilate to the shoot apex, for example following dis- placement of the short day or on removal of atmospheric CO2 during the last 12 h of exposure to a 20-h long day. Also, the flowering response to radiant flux density during the second half of a long day shows an optimum between 15 and 70 J m-2 s-1, with reduced flowering both above and below this irradiance. Thus, although there is no absolute requirement for long days to induce flowering in S. alba, light reactions cther than photosynthesis probably contribute to photoperiodic induction in this species.

Response of Barley Shoot Apices to Application of Gibberellic Acid and Abscisic Acid: Dependence on Tissue Sensitivity

1978 ◽  
Vol 5 (5) ◽  
pp. 581 ◽  
Author(s):  
PB Nicholls
Keyword(s):  
Abscisic Acid ◽  
Gibberellic Acid ◽  
Acid Treatment ◽  
Apical Meristem ◽  
Internode Elongation ◽  
Shoot Apices ◽  
Tissue Sensitivity ◽  
Short Days ◽  
Gibberellic Acid Treatment ◽  
Acid Dependence

Stimulation by gibberellic acid of rachis internode elongation in barley grown in short days was dependent on either the timing of application or on the amount applied in a dose at day 10. There was no immediate rachis internode elongation in response to gibberellic acid treatment until floret initials appeared and then only if sufficient gibberellic acid was present in the shoot apices of the barley plants grown in short days. Applications of gibberellic acid promoted the growth of the double-ridge meristem (upper ridge only) and this resulted in a group of abnormal spikelets being formed on the lower six nodes of the inflorescence, all of which were characterized by enhanced growth of the rachilla apical meristem. In a 2 × 2 factorial experiment with gibberellic acid, abscisic acid was found to slightly reduce the growth rate of the vegetative barley apex between days 10 and 14. Abrupt cessation of primordium formation, coincident with the appearance of stamen initials, was observed following continued application of both gibberellic acid and abscisic acid whereas neither hormone alone had this effect. Enhanced growth of the rachilla apical meristem of the basal six spikelets following application of gibberellic acid resulted in the formation of branched inflorescences, and this result was not altered by the addition of abscisic acid to the treatment.

scholarly journals Season production of 11 Panicum maximun cultivars harvested at a 45-day interval

1969 ◽  
Vol 75 (1) ◽  
pp. 61-66
Author(s):  
Rafael Ramos-Santana ◽  
José E. Rodríguez-Arroyo
Keyword(s):  
Dry Matter ◽  
Long Day ◽  
True Digestibility ◽  
Harvest Intervals ◽  
Productive Potential ◽  
Guinea Grass ◽  
Short Days

The productive potential of 11 guinea grass forage genotypes was evaluated at harvest intervals of 45 days during the short and long day seasons. Guinea grass genotypes PRPI 3637 and 3622 produced the highest dry matter yields. P. maximun PRPI 12917 (cultivar Makueny) was not different from 3637 or 3622 during short days; however, during long days it differed from cultivar 3637. In vitro true digestibility (IVTD) estimated by the predicting equation of Arroyo-Aguilú and Coward-Lord was similar for most cultivars under evaluation. Cultivar Guadalupe produced the highest IVTD values during both seasons. Among all genotypes, P. maximun 3637 and 3634 consistently had the highest average regrowth percentages and the best capacity to recover.

scholarly journals Effect of Meristem Position and Medium on in Vitro Meristem Culture of Alstroemeria

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 461C-461
Author(s):  
Alessandro Chiari ◽  
Mark P. Bridgen
Keyword(s):  
Gibberellic Acid ◽  
Culture Media ◽  
Pantothenic Acid ◽  
Meristem Culture ◽  
Vegetative Shoot ◽  
Shoot Apices ◽  
Apical Meristems ◽  
In Vitro Plants ◽  
Axillary Meristems

Meristems from three different positions were excised from in vitro plants of Alstroemeria genotype A30. Explants were removed from the most-distal vegetative shoot apical meristems, rhizome tip apical meristems, and rhizome tip axillary meristems. Meristems were cultured on four different media to compare the effect of meristem position and medium on the ability to produce Alstroemeria rhizomes from meristems. The meristem culture media were Murashige & Skoog salts plus 8.39 μM pantothenic acid, 1.19 μM thiamine, and 0.55 mm myo-inositol (MSM), MSM plus 8.88 μM of 6-benzylaminopurine (BA), MSM plus 8.88 μM BA, and 0.72 μM gibberellic acid (GA3), and MSM plus 0.72 μM GA3. Meristems that were removed from the vegetative shoot apices did not develop rhizomes on any medium. Rhizome tip apical meristems developed less than 10% rhizomes when subcultured on media containing BA and GA3. However, rhizome tip axillary meristems developed rhizomes on all media with best results achieved when the medium was supplemented with BA.

scholarly journals In Vitro Regeneration of Medicinally Important Shrub Carissa Opaca from Shoot Apices and Nodal Segments

2018 ◽  
Vol 3 ◽  
pp. 23-29
Author(s):  
Ali Ahmad ◽  
Bilal Haider Abbasi ◽  
Muhammad Zia
Keyword(s):  
Acetic Acid ◽  
Gibberellic Acid ◽  
Genetic Transformation ◽  
Nodal Segments ◽  
Naphthalene Acetic Acid ◽  
Ex Vitro ◽  
Shoot Apices ◽  
Murashige And Skoog Medium ◽  
Carissa Opaca

The study was aimed to develop efficient shoot regeneration fromex vitroexplants ofCarissa opaca, an imperative medicinal reservoir. Shoot apices and nodal segments were inoculated on MS (Murashige and Skoog) medium containing BAP (6-bezyl amino purine) and Kin (Kinetin) alone and in combination with NAA (naphthalene acetic acid) and GA3(Gibberellic acid). Higher concentrations of both cytokinins were found effective for regeneration from both explants. However, gibberellic acid and NAA addition with cytokinin, no persuading results were achieved. The shoot apices were found more effective inin vitroregeneration than nodal segments.The protocol can be effectively used for in vitro multiplication ofC. opaca, genetic transformation, and secondary metabolite production.

In vitro studies of floral shoot apices of Pharbitis nil

1970 ◽  
Vol 48 (7) ◽  
pp. 1355-1358 ◽  
Author(s):  
D. S. Bhar
Keyword(s):  
Dark Period ◽  
Floral Organ ◽  
In Vitro Studies ◽  
Pharbitis Nil ◽  
Shoot Apices ◽  
Intact Plants ◽  
Full Complement

Shoot apices of Pharbitis nil were excised and cultured in vitro at different intervals after the intact plants were photoperiodically induced. The induced apices excised immediately after and up to 24 h after an inductive dark period, grew vegetatively for at least 4 weeks in culture. The apices excised and cultured from intact plants at 36 and 48 h after induction initiated a full complement of floral-organ primordia when observed after 4 weeks of growth.

Effect of photoperiod and gonadectomy on testosterone metabolism in vitro by the prostate of the golden hamster

1983 ◽  
Vol 97 (2) ◽  
pp. 187-191 ◽  
Author(s):  
V. Lucini ◽  
L. Bottoni ◽  
R. Massa
Keyword(s):  
Golden Hamster ◽  
The Other ◽  
Testosterone Metabolism ◽  
Golden Hamsters ◽  
Long Day ◽  
The Mean ◽  
Short Days

Testosterone metabolism was studied in vitro in the prostate of intact and castrated golden hamsters maintained either in short days (8 h light: 16 h darkness, 8L : 16D) or in long days (14L : 10D). Testosterone was found to be converted into 17β-hydroxy-5α-androstan-3-one (5α-DHT), 5α-androstane-3α, 17β-diol, 5α-androstane-3, 17-dione and androstenedione. The mean conversion of testosterone to 5α-DHT was higher in prostates from animals maintained in long days than in short days (P < 0·0025) while that to androstenedione was higher in short days (P <0·0005); no significant changes in the formation of the other three metabolites were noted. Castration of animals maintained in short days resulted in a significant (P <0·05) decrease in the mean conversion to all four metabolites. In contrast, castration of animals kept in a long-day regime caused a significant (P <0·01) decrease in the mean formation of 5α-DHT but a significant (P <0·05) increase in the mean formation of 5α-androstane-3α, 17β-diol.

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