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  • Electronic Resource  (12)
  • 1990-1994  (12)
  • 1955-1959
  • 1850-1859
  • 1990  (12)
  • protoplasts
  • 1
    ISSN: 1432-203X
    Keywords: Somatic embryogenesis ; protoplasts ; Brassica nigra ; plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method to obtain plants from embryogenic callus of Brassica nigra and protoplasts of hypocotyl expiants is described. Callus was initiated on Murashige and Skoog medium containing kinetin (kn) and 2,4-dichlorophenoxy acetic acid (2,4-D). Lowering of auxin induced embryo formation. Supplementation with gibberellic acid (GA3) enhanced embryogenic response tenfold. Passage through liquid medium devoid of growth regulators was essential for the growth of embryos. Secondary embryos were produced on transfer to solid basal medium. Embryogenic callus retained its morphogenic ability even after 12 subcultures. Both primary and secondary embryos produced fertile plants. Hypocotyl-derived protoplasts were also regenerated to plants following the same protocol. The survival of plants on transfer to soil was about 80%. The seeds from plants derived from callus and protoplasts were viable.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 15 (1990), S. 485-496 
    ISSN: 1573-5028
    Keywords: protoplasts ; P.R. proteins ; tobacco ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used 2-dimensional (2D) non-equilibrium pH gradient gel electrophoresis (NEPHGE) of in vitro synthesized proteins and northern hybridization with labelled cDNAs coding for three pathogenesis related (P.R.) proteins, to analyze the shift in mRNA content induced by the isolation and culture of tobacco mesophyll protoplasts. The in vitro protein pattern of mRNAs from freshly isolated protoplasts is characterized by the absence of most leaf spots and the appearance of 19 new spots. After 6 hours of culture, the mRNAs coding for the P.R. proteins become detectable and after 12 hours the protoplasts contain an mRNA population almost typical of callus cells. The different steps involved in the isolation and culture of protoplasts were analysed. Cutting off the leaf and sterilization do not change the mRNA set. In contrast, the mechanical injury applied to the leaf in order to facilitate the penetration of the enzymatic mixture induces a modification of the mRNA content identical to that resulting from protoplast isolation. Wounding is the essential event inducing dedifferentiation. Varying the culture medium and conditions leads to only limited modifications of the mRNA pattern. These results are discussed on the basis of present knowledge of the reaction of the plant to wounding and we suggest that wound healing callus and in vitro callus correspond to the same differentiation state.
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  • 3
    ISSN: 1573-5028
    Keywords: maize gene expression ; protoplasts ; transient assays ; transcriptional regulation ; zein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three DNA regions required for high levels of transcription were identified by transient gene expression analysis of the 5′ flanking region of a 19 kDa α-zein gene. For these analyses, the zein promoter region was fused to the β-glucuronidase (GUS) gene and assayed by transient expression in carrot protoplasts. A 107-bp sequence (-114/-8) containing the TATA box resulted in low levels of GUS activity. Addition of the proximal 75 bp (-189/-114) doubled the level of GUS expression, and a further increase in expression was obtained when additional upstream sequences (-483/-226) were placed 5′ of the zein promoters. Zein upstream sequences enhanced transcription independently of the-189/-114 region. Although the-189/-114 region was not essential for transcription, it was important to obtain maximum GUS activity. A 121 bp upstream sequence (-347/-226) that contains the conserved TGTAAAG sequence gave high levels of GUS activity when placed in either orientation 5′ of the zein promoter sequences. However, nucleotides-347 to-309, containing the TGTAAAG sequence, could be deleted from this fragment without a significant change in GUS activity. Zein upstream sequences did not promote transcription of the GUS gene in somatic maize protoplasts. The upstream activating sequence from the cauliflower mosaic virus (CaMV) 35S promoter placed 5′ of deletion mutants of the zein promoter also failed to produce GUS activity above background.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5028
    Keywords: inheritance ; NPTII gene ; protoplasts ; S phase ; 3-aminobenzamide ; UV irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Freshly isolated haploid mesophyll protoplasts of Nicotiana plumbaginifolia were transformed for kanamycin resistance. In 38% of the 224 transformants analysed, transmission of the NPTII gene occurred as a homozygous trait, while 62% of the transformants were heterozygous for the trait. In the first case, the foreign DNA integration predominantly (95%) resulted in monogenic inheritance. The second group was characterized by a significant (46%) proportion of multiple insertions. However, there was no clear-cut difference in the integration pattern between the two groups. Furthermore, transformation rates were increased by 4- to 10-fold when transformed diploid protoplasts were treated with UV light or with 3-aminobenzamide. The number of insertion sites was also increased by these treatments. These results shed further light on the fate of the foreign DNA in transformed plants and on means to control or manipulate the integration event(s).
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  • 5
    ISSN: 1573-5028
    Keywords: expression vector ; heat shock ; protoplasts ; transient assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A heat-inducible expression cassette has been constructed to study the conditional expression of sense or antisense orientations of any sequence of interest in transgenic plants or plant tissues. The construct includes the promoter and all but 5 bases of the mRNA leader from the soybeanGmhsp17.5-E gene, the polylinker from pUC18 (modified to remove the ATG), and a fragment that contains the polyadenylation signal and site from the nopaline synthase gene. Analysis of transient expression of a construct containing the β-glucuronidase (GUS) coding sequence cloned in the cassette and introduced intoNicotiana plumbaginifolia protoplasts by electroporation shows that the promoter has high expression at heat shock temperatures. This construct is expressed at a roughly 80-fold higher level per unit time than a cauliflower mosaic virus 35S gene promoter-GUS construction. The heat shock promoter is regulated positively by supercoiling in this transient assay system. The level of expression of HS-GUS constructions with the polyadenylation sites from either the nopaline synthase gene or theGmhsp17.5-E gene was similar. Constructs with a perfect fusion at the 5′ end had higher levels of expression than those with the corresponding nonperfect transcriptional fusion.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 47 (1990), S. 39-44 
    ISSN: 1573-5060
    Keywords: Vitis vinifera ; grape vine ; leaves ; protoplasts ; cell wall regeneration ; division
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Experimental conditions were established that resulted in high yields and good viability of the protoplasts obtained from leaves of Vitis vinifera, cv. Chardonnay regenerated in vitro by somatic embryogenesis. The effect of factors of the culture medium and various environmental conditions upon the frequency of cell division has been examined, and a method of culture is described by which protoplasts were induced to begin division. Most protoplasts obtained in this way regenerated cell walls within the first few days and cell division occurred after 10 days of culture in a liquid medium. Some cells have divided two or even three times. Nevertheless, the cells did not continue dividing beyond this stage.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 204-205 (1990), S. 409-413 
    ISSN: 1573-5117
    Keywords: amoeba ; grazing ; enzymatic induction ; protoplasts ; seaweeds ; Trichosphaerium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A crude enzyme preparation from the marine amoeba Trichosphaerium was used to produce protoplasts from Sargassum muticum, Macrocystis pyrifera Porphyra perforata, and other red and brown marcroalgae. Cortical and medullary protoplasts of Sargassum, which were impossible to obtain using mixtures of previously available enzymes have now been prepared. Intact inner cortical and medullary protoplasts of Macrocystis, which were not observed in past isolations were obtained. Improved protoplast yields of as much as 500 fold resulted from feeding the amoebae on specific seaweeds. Cuticles of live Sargassum and Macrocystis were digested easily by the amoebae. However cuticles of autoclaved Macrocystis and those of Porphyra (fresh or autoclaved) were eaten last. In spite of the absence of identifiable extracellular enzymatic activity in the medium the amoebae were able to ‘cut’ and consume live fronds and blocks of gelled agars carrageenans, and alginates.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-5044
    Keywords: Brassica oleracea ; protoplasts ; regeneration ; cytoplasmic traits ; mitochondrial DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nearly 1000 plants have been regenerated from leaf protoplasts of two cauliflower (Brassica oleracea ssp.botrytis) alloplasmic inbred lines. One line (7642A) carried the Ogura (R1) cms cytoplasm derived from radish; the other line (7642B) carried a normalBrassica cytoplasm and was the fertile maintainer for the cms line. The majority of regenerated plants displayed normal vegetative morphology; they formed normal cauliflower heads and retained the floral characteristics of seed-grown plants from which they were derived. We found no change in either male sterility or in the low temperature-induced chlorosis associated with the 7642A line. Mitochondrial DNA analysis by hybridization with five cloned mtDNA probes revealed no apparent alteration in 75 regenerated plants of both lines. These results indicate that cytoplasmic traits inBrassica oleracea are stable after one cycle of in vitro culture and regeneration.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 23 (1990), S. 181-186 
    ISSN: 1573-5044
    Keywords: heritability ; protoplasts ; RFLPs ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetics of tissue culture response in potato has been examined by analysing a sample of dihaploids (2n=2x=24) extracted from tetraploid parents (4n=4x=48). The genotypes were screened for rate of nodal multiplication, in vitro tuberisation, regeneration from leaf discs and protoplast plating efficiency. Significant differences were detected between dihaploids for the traits measured and this indicates that tissue culture response in the tetraploid parents must be in the heterozygous condition. Estimates of the broad sense heritabilities were calculated together with the number of genes or effective factors involved in the control of the traits. These estimates indicate that tissue culture response in potato is under relatively simple genetic control and “blocks of genes” may be located on specific chromosomes. The inheritance of RFLP markers in the segregating dihaploid population was also monitored and the potential of using molecular markers linked to gene(s) controlling tissue culture response is discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 20 (1990), S. 75-79 
    ISSN: 1573-5044
    Keywords: Lens culinaris ; protoplasts ; osmoticum ; agarose ; callus formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts of Lens culinaris Medik. cv. Eston were isolated from epicotyl tissues of seedlings grown on Murashige & Skoog basal medium. For isolating the protoplasts, epicotyl tissues were digested for 12–14 h at 25°C in an isolation mixture (pH 5.7) containing 1% Cellulase RS, 0.5% Driselase, 0.25% Pectolyase Y23, 0.2M calcium chloride, 10 mM mannitol and 10 mM MES. Protoplasts were purified by flotation over 20% sucrose and washed with 0.2 M calcium chloride solution supplemented with 10 mM mannitol. Purified protoplasts were cultured at a density of 105 ml-1 in agarose (Seaplaque, 0.6%) blocks which were suspended in an identical but liquid KM8P culture medium lacking amino acids, ammonium nitrate, and coconut water but containing 0.35 M glucose and a growth regulator complement of either 2.2 μM 2,4-dichlorophenoxyacetic acid (2,4-D), 2.7 μM naphthaleneacetic acid (NAA), 2.3 μM N-(2-furanylmethyl)-1H-purine-6-amine (kinetin), 2.2 μM benzylamino purine (BAP), 2.3 μM 2-methyl-4-(1H-purine-6-ylamino)-2-buten-1-ol (zeatin), and 1.4 μM gibberellic acid (GA3), or 5.4 μM NAA and 2.2 μM each of 2,4-D and BAP. The osmotic potential of the liquid culture medium was gradually reduced over a period of 3 weeks by replacing the spent medium with a fresh medium containing 0.25, 0.1 and 0 M glucose at weekly intervals. About 6% of the dividing protoplasts developed into cell colonies after 3 weeks of culture at 25°C in diffuse light (10 μE m-2s-1). In 35–42 days the microcolonies were about 1 mm in diameter and developed into calli on transfer to agar-solidified B5 medium supplemented with growth regulators used in the protoplast culture medium and 5 mM glutamine. Attempts to regenerate plants from protoplast-derived calli have so far been unsuccessful.
    Type of Medium: Electronic Resource
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  • 11
    ISSN: 1573-5044
    Keywords: calcium ; Lycopersicon esculentum ; myo-inositol ; photoperiod ; protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants from four cultivars of Lycopersicon esculentum were grown under different conditions, in controlled environment chambers. Low light intensity, long photoperiod (16 h), 25° C/17°C temperature alternance (day/night) were found to be the most convenient conditions for obtaining viable protoplasts. The use of myo-inositol as an osmoticum in the digestion medium and the adjustment of the pH to 6.5, instead of the usual 5.8, for this medium increased the yield of viable protoplasts and enhanced their stability. Under these conditions neither pretreatment (dark and cold treatments), nor preplasmolysis of leaf tissues, were required before protoplast isolation. The concentrations of ammonium nitrate, calcium chloride, myo-inositol, and sucrose were found to be critical for the success of protoplast culture. A medium containing 5 mM ammonium nitrate, 40 mM calcium chloride, 10 mg l-1 adenine sulfate, 0.5% myo-inositol and 6% sucrose gave sustained protoplast divisions. Under these conditions, plating efficiency ranged from 5% for the cultivar Lukulus to 15% for the cultivar Golden Sunrise.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 23 (1990), S. 107-114 
    ISSN: 1573-5044
    Keywords: electrofusion ; grape ; polyethylene glycol ; protoplasts ; vacuoles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultured grape cells accumulate anthocyanins in vacuoles rather than secreting them into the nutrient medium. Therefore, grape cells that contain tonoplast segments in their plasmalemma should be capable of excreting anthocyanins rather than sequestering them in their vacuoles. In initial attempts to construct such ‘novel’ cells, small vacuoles were fused with the plasmalemma of cultured plant cells. Protoplasts were isolated from grape calluses that produce and accumulate anthocyanins. Small vacuoles were formed by gently rupturing vacuoles isolated from grape protoplasts. Although small vacuoles and protoplasts became aligned in an AC field, the tonoplast and plasmalemma did not readily fuse when subjected to 3 DC pulses of 1200 V cm−1 for 50 μs each. Changes in the intensity, number and/or duration of the DC pulses had no effect on the fusion process. When 1.0% polyethylene glycol was added to the electrofusion buffer, however, small vacuoles and protoplasts fused within a few minutes after the DC pulses were applied. These ‘novel’ grape cells remained viable for several hours.
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