共查询到20条相似文献,搜索用时 31 毫秒
1.
Sanjay Gupta V. K. Khanna Rameshwar Singh G. K. Garg 《Plant Cell, Tissue and Organ Culture》2006,86(3):379-388
Development of suitable strategy to overcome genotypic limitations of in vitro regeneration in sorghum would help utilize high yielding but poor tissue culture responsive genotypes in genetic manipulation programmes. A factorial experiment was conducted with two explants (immature embryos and inflorescences), eight genotypes (five Sorghum sudanense and three Sorghum bicolor genotypes), three levels of 2,4-D (1 mg l−1, 3 mg l−1, and 5 mg l−1), and two levels of kinetin (0.0 mg l−1 and 0.5 mg l−1). The induced callus was transferred to the regeneration media with factorial combinations of IAA (1.0 mg l−1 and 2.0 mg l−1) and kinetin (0.5 mg l−1 and 1.0 mg l−1). S. sudanense regenerated at significantly higher frequency (38.91%) and produced shoots more intensely (2.2 shoots/callus) than S. bicolor (26.93%, 1.26 shoots/callus). Immature inflorescences regenerated at a much higher frequency (46.48%) and produced significantly more number of shoots (2.71 shoots/callus) than immature embryos (22.35%, 0.99 shoots/callus). Moreover, differences for plant regeneration between genotypes of the same species were minimal when using immature inflorescences. Increase in the 2,4-D concentration in callus induction media exhibited inhibitory effect on callus induction, growth, shoot induction and number of shoots/callus but inclusion of kinetin in callus induction media improved these responses. Use of immature inflorescence explant and inclusion of kinetin in callus induction media could overcome genotypic limitations of plant regeneration to a large extent. The extent of variability, heritability and expected genetic advance was more in plant regeneration traits than in callus induction traits. This indicated that the variability in respect of these attributes in the genotypes may be due to the additive gene action and selection of genotypes for these characters would be rewarding. 相似文献
2.
Meiru Li Hongqing Li Huawu Jiang Xiaoping Pan Guojiang Wu 《Plant Cell, Tissue and Organ Culture》2008,92(2):173-181
Jatropha curcas contains high amounts of oil in its seed and has been considered for bio-diesel production. A transformation procedure for
J. curcas has been established for the first time via
Agrobacterium tumefaciens infection of cotyledon disc explants. The results indicated that the efficiency of transformation using the strain LBA4404
and phosphinothricin for selection was an improvement over that with the strain EHA105 and hygromycin. About 55% of the cotyledon
explants produced phosphinothricin-resistant calluses on Murashige and Skoog (MS) medium supplemented with 1.5 mg l−1 benzyladenine (BA), 0.05 mg l−1 3–indolebutyric acid (IBA), 1 mg l−1 phosphinothricin and 500 mg l−1 cefotaxime after 4 weeks. Shoots were regenerated following transfer of the resistant calli to shoot induction medium containing
1.5 mg l−1 BA, 0.05 mg l−1 IBA, 0.5 mg l−1 gibberellic acid (GA3), 1 mg l−1 phosphinothricin and 250 mg l−1 cefotaxime, and about 33% of the resistant calli differentiated into shoots. Finally, the resistant shoots were rooted on
1/2 MS media supplemented with 0.3 mg l−1 IBA at a rate of 78%. The transgenic nature of the transformants was demonstrated by the detection of β-glucuronidase activity
in the primary transformants and by PCR and Southern hybridization analysis. 13% of the total inoculated explants produced
transgenic plants after approximately 4 months. The procedure described will be useful for both, the introduction of desired
genes into J. curcas and the molecular analysis of gene function. 相似文献
3.
An efficient and simple method for high frequency plant regeneration from immature cotyledons of mungbean is described. Immature
cotyledons isolated from embryos, one week prior to harvest were cultured on MS medium with combinations of growth regulators
such as benzyladenine (1 or 2 mg l−1), thidiazuron (0.1 or 0.5 mg l−1), gibberellic acid (0.1 mg l−1) and indole-3-acetic acid (0.1 or 0.5 mg l−1). A large number of greenish shoot primordia were initiated from the entire surface of the cotyledons in some of the growth
regulators. Medium supplemented with benzyladenine (2 mg l−1) in combination with indole-3-acetic acid (0.5 mg l−1) produced the best response. On subculture to the same medium, well developed shoots were obtained. Addition of 0.5% activated
charcoal to the shoot initiation medium completely inhibited initiation of shoot primordia. The shoot buds could be rooted
on medium supplemented with 0.1 mg l−1 indole butyric acid and plants transferred to soil.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
Jose Luis Gama-Flores Maria Elena Castellanos-Paez S. S. S. Sarma S. Nandini 《Hydrobiologia》2007,593(1):201-208
Heavy metals are widely recognized as potential toxic agents to zooplankton, yet experiments are usually performed with a
continuous exposure to the metal being analyzed. Here we describe experiments that examined the influence of pulsed exposure
of the heavy metals copper and cadmium to a parthenogenetic population of the planktonic rotifer Brachionus calyciflorus. Our protocol called for exposure durations of 3, 6, 12, and 24 h to either copper (as CuSO4) at concentrations of 0.0375, 0.075, 0.15 mg l−1 or cadmium (as CdCl2) at concentration of 0.025, 0.05, 0.1 mg l−1. Control animals were treated in similar ways but did not receive exposure to heavy metals. Four end points were used to
evaluate the outcome of exposure: population growth (r), body size, egg ratio, and egg hatching percent. Increase in heavy metal concentration and exposure time had an adverse
influence on the population growth of B. calyciflorus. However, while the response of B. calyciflorus was similar for both heavy metals, the magnitude of the impact of cadmium was more severe. Population growth varied depending
on which heavy metal was tested, as well as its concentration and the duration of exposure (r = 0.11–0.28 day−1). There was a significant reduction in lorica size of B. calyciflorus subjected to different exposure times and concentrations of both Cd and Cu. Egg ratios were inversely related to population
density in controls and in treatments involving Cu, but not for Cd. While nearly 100% of eggs hatched in the control treatments,
egg hatching in experimental treatments containing Cu, were reduced (range = 16–41%) depending on the exposure time and the
concentration.
Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont & R. Rico-Martínez
Advances in Rotifer Research 相似文献
5.
Cell suspension cultures of Commiphora wightii, grown in modified MS medium containing 2,4-dichlorophenoxyacetic acid (0.5 mg l−1) and kinetin (0.25 mg l−1), produced ∼5 μg guggulsterone g−1 dry wt. In a 2 l stirred tank bioreactor, the biomass was 5.5 g l−1 and total guggulsterone was 36 μg l−1. 相似文献
6.
In the present study an efficient somatic embryogenesis method has been developed in Catharanthus roseus. Friable embryogenic callus was induced from hypocotyl of in
vitro germinated seeds on Murashige and Skoog basal nutrient media supplemented with various auxins particularly 2,4-D (1.0 mg l−1). However, only NAA (1.0 mg l−1) produced somatic embryos in cultures. Embryo proliferation was even high on the same medium added with BAP. Cotyledonary
somatic embryo germinated and converted into plantlets in BAP (0.5 mg l−1) added medium following a treatment with gibberellic acid (1.0 mg l−1) for maturation. Carbon sources and concentrations had a marked influence on maturation process. Plantlet conversion was
better achieved when embryos were matured on 3% fructose or 3–6% maltose. The result discussed in this paper indicates that
somatic embryos were produced in numbers and converted plantlets can be used as raw material, genetic modification to embryo
precursor cell may improve alkaloid yield further. 相似文献
7.
Wenyan Wang Chenggang Wang Bang-Lian Huang Bangquan Huang 《Plant Cell, Tissue and Organ Culture》2008,92(2):165-171
A protocol was developed for regeneration and Agrobacterium-mediated genetic transformation of Lesquerella fendleri. Calli were first induced from hypocotyls and cotyledons on MS plus 0.5 mg l−1 BA, 1 mg l−1 NAA and 1 mg l−1 2,4-D, then co-cultivated for 2–3 days in darkness on MS supplemented with 0.5 mg l−1 BA, 0.2 mg l−1 NAA and 100 μmol l−1As together with Agrobacterium tumefaciens strain EHA105/pCAMBIA1301 that harbored genes for uidA (GUS) and hygromycin resistance. Following co-cultivation, calli transfected by A. tumefaciens were transferred to MS with 0.5 mg l−1 BA, 0.2 mg l−1NAA, 500 mg l−1 Cef and 10 mg l−1 hygromycin and cultured for 10 days, then the hygromycin was increased to 20 mg l−1 on the same medium. After 4 weeks the resistant regenerants were transferred to MS with 0.5 mg l−1BA, 0.2 mg l−1 NAA, 500 mg l−1 Cef and 25 mg l−1 hygromycin for further selections. Transgenic plants were confirmed by polymerase chain reaction analysis, GUS histochemical
assay and genomic Southern blot hybridization. With this approach, the average regeneration frequency from transfected calli
was 22.70%, and the number of regenerated shoots per callus was 6–13. Overall results described in this study demonstrate
that Agrobacterium-mediated transformation is a promising approach for improvement of this Lesquerella species. 相似文献
8.
Protoplasts were isolated from cell suspensions derived from cotyledon and hypocotyl Gentiana kurroo (Royle). Cell walls were digested with an enzyme cocktail containing cellulase, macerozyme, driselase, hemicellulase and
pectolyase in CPW solution. Protoplast viability ranged from 88 to 96%. Three techniques of culture and six media were evaluated
in terms of their efficiency in producing viable cultures and regenerating whole plants. With liquid culture, cell division
occurred in only a low number of the protoplasts isolated, and no plant regeneration was successful. Cell division occurred
within 2 or 3 days in case of agarose solidified media. After 10 days of culture, the number of dividing cells was the highest
with modified MS medium in which NH4NO3 was replaced with 3.0 g l−1 glutamine. The best results were obtained with agarose bead cultures: plating efficiency was 68.7% and 58.1% for protoplasts
isolated from cotyledon and hypocotyl derived suspensions, respectively. The results were achieved with using medium containing
0.5 mg l−1 2,4-D + 1.0 mg l−1 kinetin or 2.0 mg l−1 BAP + 1.0 mg l−1 dicamba + 0.1 mg l−1 NAA + 80 mg l−1 adenine sulfate. Protocalluses transferred on the following composition of plant growth regulators: 0.5 mg l−1 2,4-D + 1.0 mg l−1 kinetin or 1.0 mg l−1 kinetin + 0.5 mg l−1 GA3 + 80.0 mg l−1 adenine sulfate developed in embryogenic cultures. However, the best embryo production occurred with the first one. Later
embryos were transferred to half-strength MS mineral salts to promote plants formation. Flow cytometry studies revealed increased
amounts of DNA in about one third of the regenerants. 相似文献
9.
Plant regeneration from protoplast culture of Crocus cancellatus was investigated using regenerable embryogenic calli obtained from shoot meristem culture on LS (Linsmaier and Skoog, 1965)
medium containing 4 mg l−1 kinetin and 1 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D). Protoplasts were isolated directly from embryogenic calli. The best protoplast growth
was found on those embedded in Ca-alginate beads and cultured with nurse cells in MS (Murashige and Skoog, 1962) medium supplemented
with 2 mg l−1 kinetin, 1 mg l−1 2,4-D and 100 mg l−1 ascorbic acid at 25 °C in darkness. After 4–5 weeks of culture, microcalli appeared on the surface of the Ca-alginate beads,
but the protoplasts without immobilization in Ca-alginate beads showed very low cell division. Growth of the microcalli in
the medium with nurse cells was much better than in the medium without nurse cells. Transferring beads onto half strength
MS medium supplemented with 0.2 mg l−1 kinetin and 0.1 mg l−1 2,4-D, increased the growth of embryogenic calli. Somatic embryo development was observed either on half strength MS medium
growth regulator free or with 1 mg l−1 abscisic acid. Matured embryos germinated on half strength MS medium containing 25 mg l−1 of gibberelic acid. Plantlet formation was obtained on half strength MS medium containing 1 mg l−1 6-benzyladenine and 1 mg l−1 α-naphthaleneacetic acid at 20 °C in a 16/8 h light/dark cycle.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
Chaohua Hu Lei Zhang David Hamilton Wenbing Zhou Tewu Yang Duanwei Zhu 《Hydrobiologia》2007,579(1):211-218
Eichhornia crassipes (Mart.) has strong ability to remove Cu2+ from copper-contaminated water. Physiological responses in E. crassipes exposed to known concentrations of Cu2+ were examined in this study, and demonstrated that E. crassipes could accumulate 314 mg kg−1 dry weight of Cu when exposed to 5 mg l−1 of Cu2+ for periods up to 14 d. However, there were marked changes in physiology of the plant commencing at Cu2+ concentrations of 1 mg l−1. Results of this study showed that E. crassipes could tolerate moderate concentrations (i.e. 0.5 mg l−1) of Cu2+, without significant changes in photosynthetic pigment concentrations, while high concentrations (i.e. 5 and 10 mg l−1) of Cu2+ resulted in substantial loss in pigment concentrations. Increases in malondiadehyde (MDA) content were also demonstrated
in plant exposure to high Cu2+ concentrations. Soluble protein content increased to a level slightly higher than the control at <0.5 mg l−1 of Cu2+, but then decreased with exposure to >1 mg l−1 of Cu2+. Our results suggest that E. crassipes has a substantial capacity to accumulate copper when cultivated at moderate concentrations of Cu2+, without marked changes in its physiology. The findings indicate that E. crassipes is a promising possibility for phytoremediation of moderately Cu-contaminated water bodies.
Handling editor: S. M. Thomaz 相似文献
11.
Paclitaxel and 10-deacetylbaccatin III (10-DAB III) were produced in suspension cultures of Taxus × media var. Hicksii grown in shake-flasks and in a 7-l bioreactor reaching, in the bioreactor, 4.4 mg l−1 (on day 14) and 37.5 mg l−1 (on day 11). In shake-flasks the highest total content of paclitaxel and 10-DAB III was 7.3 mg l−1 (on day 4) and 8.8 mg l−1 (on day 18). Phenylalanine, at 0.05 mM, increased paclitaxel accumulation in cells cultivated in bioreactor and flasks 30-fold and 9-fold (from 0.02 mg l−1 to 0.6 mg l−1 and to 0.2 mg l−1, respectively). The 10-DAB III content in cells from flasks was increased from 0.4 mg l−1 to 1.6 mg l−1. 相似文献
12.
Tissue culture and plant regeneration of blue grama grass, Bouteloua gracilis (H.B.K.) Lag. Ex Steud
Gerardo Armando Aguado-Santacruz José Luis Cabrera-Ponce Víctor Olalde-Portugal M. A. Rosario Sánchez-González Judith Márouez-Guzmán Luis Herrera-Estrella 《In vitro cellular & developmental biology. Plant》2001,37(2):182-189
Summary As a first step towards applying biotechnology to blue grama, Bouteloua gracilis (H. B. K.) Lag. ex Steud., we have developed a regenerable tissue culture system for this grass. Shoot apices were isolated
from 3-d-old seedlings and cultured in 15 different growth regulator formulations combining 2,4-dichlorophenoxyacetic acid
(2,4-D), Picloram (4-amino-3, 5,6-trichloropicolinic acid), N6-benzyladenine (BA) or adenine (6-aminopurine). The highest induction of organogenic callus was obtained with formulations
containing 1 mg l−1 (4.52 μM) 2,4-D plus 0.5 mg l−1 (2.22 μM) BA. and 2 mg l−1 (8.88 μM) BA plus 1 mg l−1 (4.14 μM) Picloram with or without 40 mg l−1 (296.08 μM) adenine. Lower frequencies of induction were obtained for embryogenic as compared to organogenic callus. The most efficient
treatments for induction of embryogenic callus contained 2 mg l−1 (9.05 μM) 2,4-D combined with 0.25 (1.11 μM) or 0.50 mg l−1 (2.22 μM) BA, or 1 mg l−1 (4.52 μM) 2,4-D with 0.50 mg l−1 (2.22 μM) BA. Regeneration was achieved in hormonefree Murashige anmd Skoog (MS) medium, half-strength MS medium or MS medium plus
1 mg l−1 (1.44 μM) gibberellic acid. The number of plantlets regenerated per 500 mg callus fresh weight on MS medium ranged from 9 for 2 mg
l−1 (9.05 μM) 2,4-D to 62.2 for induction medium containing 2 mg l−1 (8,28 μM) Picloram, 1 mg l−1 (4.44 μM) BA and 40 mg l−1 (296.08 μM) adenine. Regnerated plants grown in soil under greenhouse conditions reached maturity and produced seeds. 相似文献
13.
Wen Liu Xuesen Chen Guanjun Liu Qing Liang Tianming He Jianrong Feng 《Plant Cell, Tissue and Organ Culture》2007,88(3):289-299
Embryo rescue technique was used successfully to produce interspecific hybrids by crossing peach (P. persica) as a female parent with apricot (P. armeniaca) and plum (P. salicica). In those crosses that had ‘Yuhualu’ or ‘Zhonghuashoutao’ as female parents, hybrid embryos aborted from the 7th or 8th
week after pollination mainly due to post-pollination incompatibility. An embryo rescue protocol was established to rescue
such embryos and recover hybrid plants. Modified half-strength MS medium containing 4 mg l−1 6-BA and 0.5 mg l−1 IBA produced up to 90% germination in the embryos. Modified MS medium with 1.0 mg l−1 6-BA and 1.0 mg l−1 IBA gave the highest bud induction and multiplication whereas modified MS medium containing 0.5 mg l−1 IAA and 0.2 mg l−1 NAA gave the best rooting percentage. All the hybrids obtained using this embryo rescue technique were verified using simple
sequence repeat (SSR) markers. A series of pollen treatments were carried out to partially overcome pre-pollination incompatibility,
and it was found accidentally that pollen treatment with electrostatic field not only improved pollen germination but also
increased the multiplication coefficient of embryo-induced shoots. 相似文献
14.
We studied the response of Brachionus patulus to different concentrations of the heavy metal Pb in the presence and absence of sediments. We conducted acute (LC50) and chronic (life table demography and population growth) toxicity tests using sediment levels of 0, 30 and 280 mg l−1 (=0, 17 and 170 NTU) and Pb at 0, 0.06 and 0.6 mg l−1. Experiments were conducted at 20 ± 1°C on a horizontal shaker and algal food (Chlorella vulgaris) was added at a density of 1.0 × 106 cells ml−1. The median lethal concentration (LC50 ± 95% Confidence intervals) of PbCl2 for B. patulus was 6.15 ± 1.08 mg l−1. Age-specific survivorship and fecundity curves showed increase in turbidity level resulted in decreased survival and offspring
production of the rotifers. Increase in Pb concentration too had a negative effect on the survival and reproductive output
of B. patulus. Statistically, average lifespan, life expectancy at birth, gross and net reproductive rates and the rate of population increase
were all significantly influenced by the concentration of Pb, turbidity level as well as the interaction of Pb concentration × turbidity
level. Rotifers exposed to 170 NTU did not grow regardless of the heavy metal concentration in the medium. Similarly, B. patulus exposed to 0.6 mg l−1 Pb did not survive beyond 10 days regardless of the turbidity level in the medium. The rate of population increase of B. patulus derived from the growth experiments was negative in all treatments containing Pb as low as 0.06 mg l−1 or turbidity level as low as 17 NTU. In treatments containing Pb or sediments, there existed no relation between the egg
ratio and the population density.
Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont and R. Rico-Martínez
Advances in Rotifer Research 相似文献
15.
D Di Simine C Finoli A Vecchio V Andreoni 《Journal of industrial microbiology & biotechnology》1998,20(2):116-120
This paper explores the use of an experimental system based on polyacrylamide-entrapped cells of Brevibacterium sp strain PBZ for the removal of metal ions from solutions. Experiments were performed in columns filled with the immobilised
cells and challenged with influents containing 20 mg L−1 of lead and 10 mg L−1 of cadmium. The cells were able to accumulate lead (about 40 mg g−1 dry biomass) and, to a lesser extent, cadmium (about 13 mg g−1 dry biomass) from solutions. In the presence of 0.4 g L−1 of glucose, the cells removed up to 53% of lead. Lead competed with cadmium for attachment to the binding sites when a solution
containing both the metals was applied. Lead removal occurred by a combination of fast physico-chemical adsorption and prolonged
low rate accumulation mediated by cell metabolism. The biosorptive capacity of the cells was sensitive to pH. Desorption of
the metal with EDTA restored the binding capability of the cells.
Received 07 July 1997/ Accepted in revised form 26 November 1997 相似文献
16.
In this paper, we would like to show unexpected morphogenic potential of cell suspensions derived from seedling explants of
Gentiana kurroo (Royle). Suspension cultures were established with the use of embryogenic callus derived from seedling explants (root, hypocotyl
and cotyledons). Proembryogenic mass proliferated in liquid MS medium supplemented with 0.5 mg l−1 2,4-D and 1.0 mg l−1 Kin. The highest growth coefficient was achieved for root derived cell suspensions. The microscopic analysis showed differences
in aggregate structure depending on their size. To assess the embryogenic capability of the particular culture, 100 mg of
cell aggregates was implanted on MS agar medium supplemented with Kin (0.0–2.0 mg l−1), GA3 (0.0–2.0 mg l−1) and AS (80.0 mg l−1). The highest number of somatic embryos was obtained for cotyledon-derived cell suspension on GA3-free medium, but the best morphological quality of embryos was observed in the presence of 0.5–1.0 mg l−1 Kin, 0.5 mg l−1 GA3 and 80.0 mg l−1 AS. The morphogenic competence of cultures also depended on the size of the aggregate fraction and was lower when size of
aggregates decreased. Flow cytometry analysis reveled luck of uniformity of regenerants derived from hypocotyl suspension
and 100% of uniformity for cotyledon suspension. 相似文献
17.
S. Haque A. H. A. Farooqi M. M. Gupta R. S. Sangwan A. Khan 《Plant Growth Regulation》2007,51(3):263-269
Pyrethrins and flower yield of pyrethrum (Chrysanthemum
cinerariaefolium Viz.) plants were determined after application of ethrel, chlormequat chloride and paclobutrazol. Ethrel at 50, 100, 250
and 500 mg l−l produced a significant positive effect on pyrethrins level, decreased plant height, while 50 and 100 mg l−l significantly increased fresh and dry flower yield. Chlormequat chloride at 1000 and 2000 mg l−l and paclobutrazol (80 and 160 mg l−l) increased pyrethrins level, single flower weight and decreased plant height and flower yield. 14C-acetate incorporation studies further substantiated positive effect of growth retardants on pyrethrins biosynthesis. The
effect of growth retardants on pyrethrins seems to be mediated through its effect on biosynthesis. 相似文献
18.
Sergio J. Ochatt 《Plant Cell, Tissue and Organ Culture》1993,33(3):315-320
Strategies were developed for the successful isolation of large numbers of highly viable protoplasts from the leaves, stems
and roots of axenic plants of the hybrid ornamental shrubWeigela ×florida cv Bristol Ruby. Protoplasts, of all sources, were cultured on different media, leading to the establishment of sustained
divisions, and coupled with the production of multi-celled (>50 cells) colonies. However, those colonies derived from mesophyll
protoplasts only were capable of a further proliferation to the callus stage. Upon transfer to a regeneration medium consisting
of MS salts and organics plus a range of concentrations of NAA and BAP, such calli underwent caulogenesis, with optimum responses
for a medium with 1.0 mg l−1 NAA and 1.0 mg l−1 BAP. The protoplast-derived shoots thus obtained were multiplied on MS medium with 0.1 mg l−1 IBA, 0.5 mg l−1 BAP and 0.1 mg l−1 GA3. Individual shoots were subsequently rooted on a half-strength MS medium plus 3.0 mg l−1 IBA, and complete protoplast-derived plants were finally transferred to the glasshouse for acclimatization. 相似文献
19.
Deeks Shannon J. Shamoun Simon F. Punja Zamir K. 《Plant Cell, Tissue and Organ Culture》2001,66(2):97-105
A procedure for in vitro culture of the parasitic flowering plant western hemlock dwarf mistletoe, Arceuthobium tsugense (Rosend.) G.N. Jones subsp. tsugense, is described. A factorial experiment evaluated the effects of media (Harvey's medium (HM) and modified White's medium (WM)),
temperatures (15 °C and 20 °C), presence or absence of light, and plant growth regulators (the auxin 2,4-dichlorophenoxyacetic
acid (2,4-D) and the cytokinin 6-benzylaminopurine (BAP) at varying concentrations (0.001 mg l−1 to 1 mg l−1)). Seed explants germinated in less than one week in culture and produced radicles. Optimal conditions for radicle elongation
were WM at 20 °C in the presence of light and without plant growth regulators. Some of the radicles split at the tip to yield
callus while others swelled to become spherical holdfasts. Holdfasts were also produced at the tips of radicles, and callus
arose from split holdfasts. Factors that promoted holdfast production were Harvey's medium, light, and 2,4-D at 1 mg l−1. Callus development from split radicles and split holdfasts was optimal on WM with 0.5 mg l−1 2,4-D and 1 mg l−1 BAP at 20 °C in the dark.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
Single-culture aerobic granules with <Emphasis Type="Italic">Acinetobacter calcoaceticus</Emphasis> 总被引:1,自引:0,他引:1
Aerobic granules are cultivated by a single bacterial strain, Acinetobacter calcoaceticus, in a sequencing batch reactor (SBR). This strain presents as a good phenol reducer and an efficient auto coagulator in the
presence of phenol, mediated by heat-sensitive adhesins proteins. Stable 2.3-mm granules were formed in the SBR following
a 7-week cultivation. These granules exhibit excellent settling attributes and degrade phenol efficiently at concentrations
of 250–2,000 mg l−1. The corresponding phenol degradation rate reached 993.6 mg phenol g−1 volatile suspended solids (VSS) day−1 at 250 mg l−1 phenol and 519.3 mg phenol g−1 VSS day−1 at 2,000 mg l−1 phenol concentration. Meanwhile, free A. calcoaceticus cells were fully inhibited at phenol >1,500 mg l−1. Denaturing gradient gel electrophoresis fingerprint profile demonstrated no genetic modification in the strain during aerobic
granulation. The present single-strain granules showed long-term structural stability and performed high phenol degrading
capacity and high phenol tolerance. The confocal laser scanning microscopic test revealed that live A. calcoaceticus cells principally distributed at 200–250 μm beneath the outer surface, with an extracellular polymeric substance layer covering
them to defend phenol toxicity. Autoaggregation assay tests demonstrated the possibly significant role of secreted proteins
on the formation of single-culture A. calcoaceticus granules. 相似文献