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1.
An investigation into the role of carbohydrates in flowering of the endangered species Kniphofia leucocephala Baijnath. (Asphodelaceae) in vitro revealed that a carbohydrate source is essential for the induction of inflorescences.
Both the concentration and type of sugar influenced the percentage of flowering, with 60 g l−1 fructose and 10 μM N6-benzyladenine (BA) inducing the best flowering response. A high percentage of flowering was also observed with 60 g l−1 glucose and 10 μM BA. The optimal concentration of sucrose for flower induction was 30 g l−1, beyond which the flowering percentage declined, but could be partially restored by increasing the BA concentration. Although
overall plant growth declined at high sugar concentrations, there does not appear to be any significant correlations between
various growth parameters and flowering percentage, suggesting that sugars play a direct role in floral transition in vitro. 相似文献
2.
Light irradiation had remarkable effects on callus growth of Oldenlandia affinis with an optimum intensity of 35 μmol m−2 s−1. Biosynthesis of kalata B1, the main cyclic peptide in O. affinis, was induced and triggered with rising irradiation intensities. The highest concentration of kalata B1, 0.49 mg g−1 DW characterised by the maximum productivity of 3.88 μg per litre and day was analysed at 120 μmol m−2 s−1, although callus growth was repressed. The light saturation point was established to be 35 μmol m−2 s−1, where kalata B1 productivity was in a similar order (3.41 μg per day) due to the higher growth index. O. affinis suspension cultures were shown to accumulate comparable specific kalata B1 concentrations in a delayed growth associated
production pattern. These were dependent on irradiation intensity (0.16 mg g−1 at 2 μmol m−2 s−1; 0.28 mg g−1 at 35 μmol m−2 s−1). The batch cultivation process resulted in a maximum productivity of 27.30 μg per litre and day with culture doubling times
of 1.16 d−1. Submers operation represented a 8-fold product enhancement compared to callus cultivation. 相似文献
3.
Regulation of flowering by green light depends on its photon flux density and involves cryptochromes
Photoperiodic lighting can promote flowering of long‐day plants (LDPs) and inhibit flowering of short‐day plants (SDPs). Red (R) and far‐red (FR) light regulate flowering through phytochromes, whereas blue light does so primarily through cryptochromes. In contrast, the role of green light in photoperiodic regulation of flowering has been inconsistent in previous studies. We grew four LDP species (two petunia cultivars, ageratum, snapdragon and Arabidopsis) and two SDP species (three chrysanthemum cultivars and marigold) in a greenhouse under truncated 9‐h short days with or without 7‐h day‐extension lighting from green light (peak = 521 nm) at 0, 2, 13 or 25 μmol m?2 s?1 or R + white (W) + FR light at 2 μmol m?2 s?1. Increasing the green photon flux density from 0 to 25 μmol m?2 s?1 accelerated flowering of all LDPs and delayed flowering of all SDPs. Petunia flowered similarly fast under R + W + FR light and moderate green light but was shorter and developed more branches under green light. To be as effective as R + W + FR light, saturation green photon flux densities were 2 μmol m?2 s?1 for LDP ageratum and SDP marigold and 13 μmol m?2 s?1 for LDP petunia. Snapdragon was the least sensitive to green light. In Arabidopsis, cryptochrome 2 mediated promotion of flowering under moderate green light, whereas both phytochrome B and cryptochrome 2 mediated that under R + W + FR light. We conclude that 7‐h day‐extension lighting from green light‐emitting diodes can control flowering of photoperiodic ornamentals and that in Arabidopsis, cryptochrome 2 mediates promotion of flowering under green light. 相似文献
4.
A. E. Solovchenko I. Khozin-Goldberg S. Didi-Cohen Z. Cohen M. N. Merzlyak 《Journal of applied phycology》2008,20(3):245-251
The effects of light and nitrogen deficiency on biomass, fatty acid content and composition were studied in Parietochloris incisa, the unicellular freshwater chlorophyte accumulating very high amounts of arachidonic-acid-rich triacylglycerols. P. incisa cultures grown on complete nutrient medium and under high light (400 μmol photons m− 2 s−1) showed the highest rate of growth in comparison to medium (200 μmol photons m−2 s−1) and low (35 μmol photons m−2 s−1) light intensity. Cultures grown under high light (on complete BG-11 medium) attained higher volumetric contents of total
fatty acids and arachidonic acid due to greater increase in biomass. Nitrogen starvation brought about a strong increase in
the arachidonic acid proportion of total fatty acids. Thus, adjustments to cultivation conditions could serve as an efficient
tool for manipulation of yield and relative content of arachidonic acid in P. incisa. The significance of the changes in lipid metabolism for adaptation of P. incisa to high-light stress and nitrogen deficiency is also discussed. 相似文献
5.
Sotiris Haliapas Traianos A. Yupsanis Thomas D. Syros George Kofidis Athanasios S. Economou 《Acta Physiologiae Plantarum》2008,30(6):807-815
Petunia × hybrida was grown under high (H), medium (M) and low (L) light intensity [photoperiod; 16 h d−1, photosynthetic photon flux density (PPFD); 360, 120 and 40 μmol m−2 s−1, respectively] as well as under end-of-day (EOD) red (R) and far-red (FR) light quality treatments [photoperiod; 14.5 h d−1, PPFD; 30 μmol m−2 s−1 EOD; 15 min, Control (C) light; without EOD light treatment]. Shoot growth, leaf anatomical and photosynthetic responses
as well as the responses of peroxidase (POD) isoforms and their specific activities following transition to flowering (1–6 weeks)
were evaluated. Flower bud formation of Petunia × hybrida was achieved at the end of the 4th week for H light treatment and on the end of the 6th week for FR light treatment. No flower
bud formation was noticed in the C and R light treatments. H and M light treatments induced lower chlorophyll (Chla, Chlb,
Chla+b) concentrations in comparison to L light. On the other hand R and FR light chlorophyll content were similar to C light.
Photosynthetic parameters [CO2 assimilation rate (A), transpiration rate (E) and stomatal conductance (g
s) values] were higher in the H light treated plants in comparison to M and L light treated plants. A, E and g
s values of R and FR light were similar to C light plants. Leaf anatomy revealed that total leaf thickness, thickness of the
contained tissues (epidermis, palisade and spongy parenchyma) and relative volume percentages of the leaf histological components
were differently affected within the light intensity and the light quality treatments. POD specific activities increased from
the 1st to the 6th week during transition to flowering. Native-PAGE analysis revealed the appearance of four anionic POD (A1–A4) isoforms in all light treatments. On the basis of the leaf anatomical, photosynthetic and plant morphological responses,
the production of high quality Petunia × hybrida plants with optimal flowering times could be achieved through the control of both light intensity and light quality. The
appearance of A1 and A2 anionic POD isoforms could be also used for successful scheduling under light treatments. 相似文献
6.
Flowering behavior of 22 strains ofLemna paucicostata collected in Japan by Yukawa and Takimoto (1976) was re-examined. The critical dark periods of the short-day strains (N-1
and N-2 types) were shorter than those determined by Yukawa and Takimoto except for that of one strain. Particularly in strains
391, 381 and 321, the differences were as large as 2.25, 1.75 and 1.5 hr, respectively. Such differences were found to be
due at least partly to the difference in night temperature; 25 C for the light and 23 C for the dark periods in the present
experiment, and 25 C throughout the light and dark periods in the previous experiment. The S type strains did not flower under
our experimental conditions (fluorescent light of 6,000 lux at 25 C) at any photoperiod tested, but flowered as a quantitative
long-day plant under natural daylight or high-intensity light (12,000 lux). Addition of sucrose or ammonium ion to the medium
suppressed the flowering of these strains under high-intensity light.
Addition of benzoic acid (1–5 μM) to 0.5 strength NH4
+-free Hutner's medium caused daylength-independent flowering in some N-1 type strains and in all N-2 type strains tested.
S type strains cultured under fluorescent light of 6,000 lux also flowered rapidly in response to benzoic acid. 相似文献
7.
In this work, an over-expressed cyclobutane pyrimidine dimer (CPD) photolyase of Synechococcus sp. PCC 7942 was used to investigate UV-C (ultraviolet irradiation of C-region) influence on photoreactivation. In vivo photoreactivation experiments indicated that the survival rate decreased from 100 to 2.6% when the UV-C flux was increased
from 1.1 to 68.5 μW/cm2. It seemed that the photolyase was easily inactivated at UV-C intensities ≥25.5 μW/cm2. Spectrometric analysis indicated that tertiary structure of the photolyase changed evidently when the UV-C fluxes were ≥25.5
μW/cm2, while the secondary structure was almost unchanged even at 170 μW/cm2. Band shift assay indicated that catalytic activity of the photolyase was impaired at fluxes ≥25.5 μW/cm2, but no significant influence on DNA-binding activity was observed. These results suggest that photoreactivation is efficient
at UV-C fluxes ≤25.5 μW/cm2, but would be impaired by intense UV-C irradiation due to structure changes of the photolyase.
Published in Russian in Biokhimiya, 2007, Vol. 72, No. 5, pp. 668–673. 相似文献
8.
Ganka Chaneva Sevdalina Furnadzhieva Kaledona Minkova Jaromir Lukavsky 《Journal of applied phycology》2007,19(5):537-544
The effect of light intensity (50–300 μmol photons m−2 s−1) and temperature (15–50°C) on chlorophyll a, carotenoid and phycobiliprotein content in Arthronema africanum biomass was studied. Maximum growth rate was measured at 300 μmol photons m−2 s−1 and 36°C after 96 h of cultivation. The chlorophyll a content increased along with the increase in light intensity and temperature and reached 2.4% of dry weight at 150 μmol photons
m−2 s−1 and 36°C, but it decreased at higher temperatures. The level of carotenoids did not change significantly under temperature
changes at illumination of 50 and 100 μmol photons m−2 s−1. Carotenoids were about 1% of the dry weight at higher light intensities: 150 and 300 μmol photons m−2 s−1. Arthronema africanum contained C-phycocyanin and allophycocyanin but no phycoerythrin. The total phycobiliprotein content was extremely high,
more than 30% of the dry algal biomass, thus the cyanobacterium could be deemed an alternative producer of C-phycocyanin.
A highest total of phycobiliproteins was reached at light intensity of 150 μmol photons m−2 s−1 and temperature of 36°C, C-phycocyanin and allophycocyanin amounting, respectively, to 23% and 12% of the dry algal biomass.
Extremely low (<15°C) and high temperatures (>47°C) decreased phycobiliprotein content regardless of light intensity. 相似文献
9.
The eco-physiological responses of three nitrogen-fixing cyanobacteria (N-fixing cyanobacteria), Aphanizomenon gracile, Anabaena minderi, and Ana. torques-reginae, to light were assessed under nutrient saturation. The N-fixing cyanobacteria were isolated into monocultures from a natural
bloom in a shallow colored lake and their growth irradiance parameters and pigment composition were assessed. The different
ecological traits related to light use (μmax, α, I
k) suggest that these N-fixing cyanobacteria are well adapted to low light conditions at sufficient nutrients, yet interspecific
differences were observed. Aphanizomenon gracile and Anabaena minderi had high relative growth rates at low irradiances (ca. 70% of those in high light), low half saturation constant for light-limited
growth (I
k < 9.09 μmol photon m−2 s−1) and high efficiency (α < 0.11 day−1 μmol photon−1 m2 s). Conversely, Ana. torques-reginae showed poorer light competitiveness: low relative growth rates at low irradiances (ca. 40% of those in high light), low α
(0.009 day−1 μmol photon−1 m2 s) and higher I
k (35.5 μmol photon m−2 s−1). Final densities in Aphanizomenon gracile and Anabaena minderi reached bloom densities at irradiances above 30 μmol photon m−2 s−1 with different hierarchy depending on irradiance, whereas Ana. torques-reginae never achieved bloom densities. All species had very low densities at irradiances ≤17 μmol photon m−2 s−1, thus no N-fixing blooms would be expected at these irradiances. Also, under prolonged darkness and at lowest irradiance
(0 and 3 μmol photon m−2 s−1) akinetes were degraded, suggesting that in ecosystems with permanently dark sediments, the prevalence of N-fixing cyanobacteria
should not be favored. All species displayed peaks of phycocyanin, but no phycoeritrin, probably due to the prevailing red
light in the ecosystem from which they were isolated. 相似文献
10.
Effects of elevated CO2 on flowering phenology and nectar production of nectar plants important for butterflies of calcareous grasslands 总被引:1,自引:0,他引:1
Effects of elevated CO2 on flowering phenology and nectar production were investigated in Trifolium pratense, Lotus corniculatus, Scabiosa columbaria, Centaurea jacea and Betonica officinalis, which are all important nectar plants for butterflies. In glasshouse experiments, juvenile plants were exposed to ambient
(350 μl l−1) and elevated (660 μl l−1) CO2 concentrations for 60–80 days. Elevated CO2 significantly enhanced the development of flower buds in C. jacea. B. officinalis flowered earlier and L. corniculatus produced more flowers under elevated CO2. In contrast, the number of flowers decreased in T. pratense. The amount of nectar per flower was not affected by elevated CO2 in the tested legumes (T. pratense and L. corniculatus), but was significantly reduced (!) in the other forbs. Elevated CO2 did not significantly affect nectar sugar concentration and composition. However, S. columbaria and C. jacea produced significantly less total sugar under elevated CO2. The nectar amino acid concentration remained unaffected in all investigated plant species, whereas the total of amino acids
produced per flower was reduced in all non-legumes. In addition, the amino acid composition changed significantly in all investigated
species except for C. jacea. The observed effects are unexpected and are a potential threat to flower visitors such as most butterflies which have no
alternative food resources to nectar. Changes in nectar production due to elevated CO2 could also have generally detrimental effects on the interactions of flowers and their pollinators.
Received: 12 September 1996 / Accepted: 9 September 1997 相似文献
11.
Echinochloa colona regeneration via organogenesis in callus cultures derived from leaf base and mesocotyl expiants andin vitro flowering were achived. Shoot bud regeneration was achieved on Murashige and Skoog’s (MS) basal medium supplemented with
6.66 μM 6-benzylaminopurine (BAP), 2.68 μM 1-naphthalene acetic acid (NAA) and 3 % (m/v) saccharose. Regenerated shoots were
rooted on half strength basal MS medium with 2 % (m/v) saccharose devoid of growth regulators. About 90 -95 % of rooted plantlets
survived in the greenhouse.In vitro flowering was induced in the regenerated shoots derived from callus on half strength MS medium supplemented with 4.4 μM BAP,
74.07 μM adeninesulphate, 0.72 μM gibberellic acid, and 3 % (m/v) saccharose. The frequency ofin vitro flowering was 80 – 90 % in three repeated experiments. Fertile seeds were recovered fromin vitro grown plantlets which were subsequently germinated into plants.
Acknowledgement: The authors wish to thank to the Department of Environment and Forests, Government of India for financial
assistance to undertake this investigation. 相似文献
12.
13.
Abstract
In the absence of inhibitory concentrations of copper, the photoautotrophic growth of Chlorella vulgaris INETI58C at 27°C exhibited a higher specific growth rate and reached a higher maximal concentration of biomass, under irradiance
of 150 W m−2, compared with 100 W m−2. However, when the mineral growth medium was supplemented with CuSO4 (range 40–80 μM), algal growth was significantly affected at the higher light intensity. In the presence of Cu2+, the increase in dry biomass was uncoupled from the increase in cell concentration since more than 16 autospores gathered
together, inside the enlarged mother cell, suggesting that copper arrested the normal bursting of the mother cell wall. At
the higher irradiance, growth medium supplementation with 80 μM of CuSO4 led to bleaching of photosynthetic pigments. No growth was observed, while, under the lower irradiance, growth was only slightly
inhibited. Results clearly showed that copper toxicity to growth of C. vulgaris was strongly influenced by light intensity. Higher light intensity elicits lethal or sublethal Cu2+ damage at concentrations lower than the threshold level for damage at lower light intensities. Cu2+ may elicit lethal or sublethal light damage at irradiances lower than the threshold level for unpolluted aquatic systems.
Received: 17 January 1997; Accepted 15 April 1997 相似文献
14.
S. M. S. D. Ramanayake W. A. V. R. Wanniarachchi T. M. A. Tennakoon 《In vitro cellular & developmental biology. Plant》2001,37(5):667-671
Summary Continuous axillary shoot proliferation and in vitro flowering were achieved using single node explants from a mature (over 70-yr-old) field clump of Dendrocalamus giganteus (giant bamboo). The shoots proliferated in a basal Murashige and Skoog medium with 6 mgl−1 (26.6 μM) N6-benzyladenine (BA) and 2% sucrose. The rate of shoot proliferation gradually increased to over three-fold before in vitro flowering took place. In vitro flowering was not the expression of a species-specific mechanism believed to occur during gregarious flowering, as the mother
clump did not flower. The rate of shoot proliferation decreased at flowering, accompanied by reversion of flowering. The development
of axillary meristems into vegetative or generative shoots depended on the level of BA. The possible role of BA, changes in
the rate of shoot proliferation decreased at flowering, accompanied by reversion of flowering. The development of axillary
meristems into vegetative or generative shoots depended on the level of BA. The possible role of BA, changes in the rate of
shoot proliferation leading to build up, and release of stress in relation to flowering and its reversion are discussed. 相似文献
15.
Gametophyte cells of brown algae Laminaria japonica were employed both in a modified silicone tubular membrane-aerated photobioreactor (bubble-less cultivation mode) and a bubble-column
photobioreactor (bubbling cultivation mode), to study different gas–liquid mixing modes on cell growth rate and cell physiological
status. With an inoculum density of 50 mg DCW l−1, in modified artificial Pacific seawater (APSW) medium at 13°C, light intensity of 60 μE m−2 s−1, light cycle of 16/8 h L/D, and aeration rate of 60 ml min−1, the specific growth rates were 0.082 d−1 for bubble-less mode and 0.070 d−1 for bubbling mode with biomass, in the form of dry cell density, increasing 10.9 and 6.8 times, respectively, during the
36 days’ photolithotrophic cultivation. The specific oxygen evolution rate under bubble-less mode was 39.6% higher than under
bubbling mode on the 18th day. The gametophyte cells grew in cell aggregates with clump sizes, at day 36, of 1.5 mm and 0.5 mm
diameter under bubble-less and bubbling mode respectively and cell injury percentages of 5.1% and 21.1%, respectively. The
silicone tubular membrane-aerated photobioreactor was better suited for the cultivation of fragile macroalgal gametophyte
cells due to the absence of hydrodynamic shear stress caused by fluid turbulence and the presence of a bubble-less gas supply. 相似文献
16.
The activity of 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase (DS-Mn, DS-Co), phenylalanine ammonia-lyase (PAL),
and chalcone synthase (CHS) was monitored at various light intensities (dark, 8.88 μmol m−2 s−1, 88.8 μmol m−2 s−1) using a strawberry cell suspension culture. DS-Mn, PAL, and CHS were found to increase significantly (p>0.05) under light intensitie of 88.8 μmol m−2 s−1 compared to those of 8.88 μmol m−2 s−1 and dark. The activity of DS-Mn, PAL, and CHS were maximum at 88.8 μmol m−2 s−1. Anthocyanin content reached a maximum after 48–60 h of culturing at 88.8 μmol m−2 s−1. DS-Co showed greater activity than DS-Mn during cell culturing, but showed no correlation with anthocyanin production and
light intensity. The CHS gene expression was continuous at a light intensity of 88.8 μmol m−2 s−1.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
17.
Mohammad K. Khalesi H. H. Beeftink R. H. Wijffels 《Marine biotechnology (New York, N.Y.)》2009,11(4):488-494
The branching zooxanthellate soft coral Sinularia flexibillis releases antimicrobial and toxic compounds with potential pharmaceutical importance. As photosynthesis by the symbiotic algae
is vital to the host, the light-dependency of the coral, including its specific growth rate (μ day−1) and the physiological response to a range of light intensities (10–1,000 μmol quanta m−2 s−1) was studied for 12 weeks. Although a range of irradiances from 100 to 400 μmol quanta m−2 s−1 was favorable for S. flexibilis, based on chlorophyll content, a light intensity around 100 μmol quanta m−2 s−1 was found to be optimal. The contents of both zooxanthellae and chlorophyll a were highest at 100 μmol quanta m−2 s−1. The specific budding rate showed almost the same pattern as the specific growth rate. The concentration of the terpene flexibilide,
produced by this species, increased at high light intensities (200–600 μmol quanta m−2 s−1). 相似文献
18.
The effects of temperature and light on the growth and geosmin production of Lyngbya kuetzingii were determined. Of the three temperatures tested, 10, 25 and 35°C, the maximal geosmin concentration and geosmin productivity
were yielded at 10°C, while the highest chl a production was observed at 25°C. In the studies on light intensity, the maximal geosmin concentration and geosmin productivity
were observed at 10 μmol m−2 s−1, while the highest chl a production was at 20 μmol m−2 s−1. It was suggested that more geosmin was synthesized with lower chl a demand. Meanwhile, the relative amounts of extra- and intracellular geosmin were investigated. Under optimum growth conditions
(20 μmol m−2 s−1, 25°C; BG-11 medium), the amounts of extracellular geosmin increased as the growth progressed and reached the maximum in
the stationary phase, while the intracellular geosmin reached its maximum value in the late exponential phase, and then began
to decline. However, under the low temperature (10°C) or light (10 μmol m−2 s−1) conditions, more intracellular geosmin was synthesized and mainly accumulated in the cells. The proportions of extracellular
geosmin were high, to 33.33 and 32.27%, respectively, during the stationary phase at 35°C and 20 μmol m−2 s−1. It was indicated that low temperature or light could stimulate geosmin production and favor the accumulation of geosmin
in cells, while more intracellular geosmin may be released into the medium at higher temperatures or optimum light intensity. 相似文献
19.
About 70% of the shoots developed from nodal explants ofGentiana triflora flowered in vitroondouble strength WPM medium containing 3% (w/v) sucrose, 0.5mg/l BA after 12 weeks of culture in a growth room at 22°Cwith continuous illumination (PPFD=60molm–2 s–1). The influences oninvitro shoot development and flowering of several factors includingthe position of the explant, requirements for sucrose, cytokinin orGA3, variations of pH and photosynthetic photon flux density (PPFD)were investigated. In vitro flowering but not shootdevelopment of G. triflora decreased notably withincreaseddistance from the apex of the shoot, indicating the presence of a floralgradient in the micropropagated shoots. Conversely, as little as 0.01mg l–1 GA3 in the medium promotedshootdevelopment but even up to 0.2 mg l–1GA3 did not induce in vitro flowering.Even though BA could substitute GA3 for a high level of shootdevelopment, it also promoted a high level of in vitroflowering at the PPFD of 60 molm–2 s–1. Sucrose was required for shootdevelopment and flowering in vitro and higher levels ofPPFD could not compensate effectively for the omission of the sugar from themedium. In general, the effects of different concentrations of BA in the mediumor variations of pH on shoot development and flowering invitro were found to be influenced by PPFD. A novel observation isthat precocious flowering of micropropagated gentian shoots did not occur ifthey were first cultured for 5 weeks in the dark before transfer to the lightcondition. 相似文献
20.
Summary
Hosta ‘Blue Vision’, a shade-adapted perennial, was successfully acclimatized in high, natural light conditions in the research
AcclimatronTM at Clemson University, Clemson, SC during the summer of 2000. The supplemental CO2 levels achieved during acclimatization were 710±113, 2396±121, and 5641±119 μmol mol−1, approximately 2×, 6×, and 15× ambient CO2. Plants were maintained in H2O-saturated atmospheres and protected from temperature increases associated with high light intensity. In the 5 wk following
ex vitro transfer, plantlet roots grew at the 2× CO2 level, but shoot biomass was unaffected. Results for the 6× and 15× CO2 levels were comparable and provided the best plantlet growth. The “doubling time’ that is characteristic of exponential growth
was 10.8 and 9.8 d for root and shoot dry weights, respectively. There was no indication of light saturation of net photosynthetic
rate (NPR) over the photosynthetic photon flux density (PPFD) range of 100–1200 μmolm−2s−1 experienced during this study. An interaction between CO2 and light intensity levels was detected for NPR of Hosta ‘Blue Vision’ with CO2 saturation occurring at approximately 2800 μmol mol−1. regardless of light level. Furthermore, at the optimal CO2 level, NPR increased quadratically as light intensity increased, and NPR was greatest at the maximum light intensity (PPFD:
1200 μmol m−2s−1). 相似文献