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  • 1
    Electronic Resource
    Electronic Resource
    Evidence for early stages of somatic embryo development in a protoplast-derived cell culture of Prunus avium (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 85 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In the genus Prunus, so far, somatic embryogenesis has not been reported either from cell suspensions or from their protoplast-derived cells. Rhizogenic cell suspensions of Prunus avium L., initiated from adventitious roots developed from cotyledon-derived callus of mature zygotic embryos, have been subcultured for more than one year without losing their morphogenic potential. A yield of 8 × 105 protoplasts ml−1 of packed cells with a viability of 98% has been routinely obtained. Optimum cell division frequency (around 2.5% at day 10 and 4–6% at day 15) occurs in agarose lenses, with Murashige and Skoog (1962. Physiol. Plant 15: 476–497)-based medium supplemented with 5 μM naphthalene acetic acid, 1 μM benzyladenine and 0.25 μM zeatin. Colony formation has been achieved after 35 days with a plating efficiency of 3–4%. Cell suspensions have been initiated from protoplast-derived callus. While the older cell cultures express a rhizogenic response, the younger ones contain early stages of somatic embryo development. Ultrastructural examination confirms the polarization of these structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1992.tb04738.x
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  • 2
    Electronic Resource
    Electronic Resource
    Genetic transformation of Ginkgo biloba by Agrobacterium tumefaciens (2000)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 108 (2000), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A reproducible protocol has been established for the transformation of Ginkgo biloba by Agrobacterium tumefaciens. Embryos were co-cultivated with Agrobacterium tumefaciens GV3101 (pGV2260) carrying the binary vector pTHW136, which contained the gus reporter gene and the nptII selectable gene, encoding the enzymes β-glucuronidase (GUS) and neomycin phophotransferase II, respectively. Transient GUS activity has been used to screen the effects of different factors on the transfer of DNA into embryos (age of embryos, infection method, composition of co-cultivation medium). Then, experimental conditions have been defined to obtain transgenic kanamycin-resistant G. biloba calluses expressing GUS activity. The highest rate of transformation (45%) was reached using 1.5-month-old embryos co-cultivated on a medium lacking mineral elements. The integration of gus and nptII genes in calluses was confirmed by polymerase chain reaction analysis and Southern blot analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2000.t01-1-100411.x
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  • 3
    Electronic Resource
    Electronic Resource
    Basic chitinases are correlated with the morphogenic response of flax cells (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Flax (Linum usitatissimum) hypocotyl protoplasts immobilized in a calcium-alginate matrix give rise to embryo-like structures. A direct correlation was established between the presence of a set of ionically-bound cell wall proteins, which includes the basic polypeptides P184 and P183 with an apparent molecular mass of 25 kDa, and this morphogenic response. Microsequencing of tryptic fragments from P184 and P183 indicated homologies with the chitinase family. These homologies were confirmed by demonstrating that, after renaturation, such proteins express a potential chitinase activity in SDS-PAGE gel containing glycol chitin as synthetic substrate. Using degenerate primers from P184 internal sequences, we isolated one partial genomic sequence of a chitinase of 626 bp from which a putative 74-amino acid sequence, disrupted by one intron, was deduced. High degrees of homology with several plant chitinases, including those expressed during somatic embryogenesis or in seeds, were observed. P184 microsequences match the corresponding sequence deduced from the chitinase PCR-fragment perfectly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1030215.x
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  • 4
    Electronic Resource
    Electronic Resource
    Transformation of Papaver somniferum cell suspension cultures with sam1 from A. thaliana results in cell lines of different S-adenosyl-L-methionine synthetase activity (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 99 (1997), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We have developed a procedure for opium poppy (Papaver somniferum) transformation using Agrobacterium tumefaciens-mediated gene delivery. Hypocotyl-derived cell suspension cultures of P. somniferum were cocultivated with A. tumefaciens strain GV3101(pMP90) harbouring either the binary vector pTHW136 or the binary vector pO35SSAM. The former contained the uidA reporter gene and the nptII selectable gene, encoding the enzymes β-glucuronidase and neomycin phosphotransferase II, respectively. The latter contained the sam1 gene encoding the enzyme S-adenosyl-L-methionine (SAM) synthetase and the nptII gene. Putatively transformed cell lines were selected on media supplemented with paromomycin. Integration of the foreign genes was confirmed by Southern blot analysis with and without PCR amplification prior to hybridization. SAM synthetase activity was measured in extracts of 5 transformed cell lines. One of them expressed a significant overactivity while two others had a lower activity than the control cell line, leading us to question the possible partial cosuppression of both the resident and the foreign sam genes. To our knowledge, this is the first report of Agrobacterium tumefaciens-mediated transformation of Papaver somniferum cell suspension cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1997.tb05407.x
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  • 5
    Electronic Resource
    Electronic Resource
    Overexpression of a heterologous sam gene encoding S-adenosylmethionine synthetase in flax (Linum usitatissimum) cells: Consequences on methylation of lignin precursors and pectins (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 112 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The Arabidopsis thaliana sam1 gene encoding S-adenosylmethionine synthetase (EC 2.5.1.6) was transferred to flax (Linum usitatissimum) cells via Agrobacterium tumefaciens. This enzyme catalyses the conversion of methionine to S-adenosylmethionine (SAM), the major methyl group donor in living cells. The aim of this work was to study the consequences of an increased SAM-synthetase (SAM-S) activity in transgenic cell lines on both the production of mono- and dimethoxylated lignin monomers and the degree of methylesterification of pectins. Hypocotyls were cocultivated with Agrobacterium tumefaciens strain GV3101 (pGV2260) harbouring the pO35SSAM binary vector carrying the sam1 gene under the control of the 35S promoter and the nptII gene for selection of putative transformed cells. Most of the transgenic cell lines exhibited a significant (up to 3.2-fold) increase in SAM-S activity compared to the controls. The results showed that for the cell lines analysed this transformation had no effect on caffeic acid O-methyltransferase (COMT, EC 2.1.1.68) in vitro activity, degree of methoxylation of lignin precursors or lignin deposition, pectin methyltransferase (PMT, EC 2.1.1) in vitro activity, but led to an increase of pectin methylesterification in friable and fast-growing transgenic cell lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1120211.x
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of nitrogen source, calcium concentration and osmotic stress on protoplasts and protoplast-derived cell cultures of Pinus Pinaster cotyledons (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 61 (1984), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The experiments described emphasize the effects of several factors crucial to the maintenance of cell divisions leading to increased cell numbers in suspension and colony formation from cotyledon protoplasts of Pinus Pinaster Ait. Osmotic potential of the incubation and culture media are critical. Reducing the osmolality from 680 mOsm kg H2O−1 during protoplast isolation to 610 mOsm kg H2O−1 during washing and culture was essential to achieve a high frequency of cell division. Survival of the cells beyond 3 weeks of culture occurs only if the calcium concentration is decreased from 5.6 mM to 1.5 mM. Glutamine as sole source of nitrogen shortens the lag phase of response of the protoplasts and increases their plating efficiency. After 6 weeks of culture, a combination of low osmolality (225 mOsm kg H2O−1) and high level of glutamine (40 mM) is a prerequisite for obtaining actively growing cell suspensions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1984.tb06360.x
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  • 7
    Electronic Resource
    Electronic Resource
    Recovery of plants from cryopreserved embryogenic cell suspensions of Pinus caribaea (1992)
    Springer
    Plant cell reports 11 (1992), S. 295-298 
    Details
    ISSN: 1432-203X
    Keywords: Cryopreservation ; Pinus caribaea ; embryogenic cell suspension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Embryogenic cell suspension cultures of Pinus caribaea var. hondurensis have been cryopreserved in liquid nitrogen for up to four months, using sucrose and dimethylsulfoxide as cryoprotectants. Post-thaw growth was obtained after a short lag phase. Removal of the remaining liquid around the cells using a filter disc favoured subsequent regrowth of the cells. These reestablished cultures maintained an embryogenic potential similar to non-frozen cultures. The embryos produced were able to regenerate into plants, which are now growing in a greenhouse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235085
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  • 8
    Electronic Resource
    Electronic Resource
    cDNA sequence, genomic organization and differential expression of three Arabidopsis genes for germin/oxalate oxidase-like proteins (1997)
    Springer
    Plant molecular biology 35 (1997), S. 459-469 
    Details
    ISSN: 1573-5028
    Keywords: circadian rhythm ; embryogeny ; germin ; globulin ; oxalate oxidase ; seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat germin is a protein expressed during germination which possesses an oxalate oxidase activity. Germin-type oxalate oxidases have been extensively studied in monocotyledons (wheat and barley) where they are thought to have important functions for development, stress response and defence against pathogens. In contrast, almost nothing is known about the germin-like proteins found in dicotyledons, gymnosperms and myxomycetes. In this work, cDNA clones for three genes (ATGER1, ATGER2 and ATGER3) encoding germin-like proteins, initially characterized as expressed sequence tags (ESTs), from Arabidopsis thaliana cDNA libraries were further characterized. In addition, we isolated and sequenced a Brassica napus cDNA which was strongly homologous to the cDNA for ATGER1. Sequence analysis and secondary structure predictions of the proteins encoded by these cDNAs showed that they possess all the characteristic features of members of the germin family and of the germin/seed globulins/sucrose binding protein superfamily. Sequence comparisons and mapping demonstrated the existence of at least two different gene families in the A. thaliana genome encoding a minimum of three genes for germins. These three genes have been mapped in three different location on the Arabidopsis genome. By northern blot hybridizations we found that these genes are differentially regulated. ATGER1 was expressed during germination, like wheat germin, but also in leaves whereas ATGER2 transcripts were exclusively found in developing embryos, like wheat pseudo-germin. ATGER3 mRNAs were found in leaves and flowers and their abundance was shown to vary during the circadian cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005833028582
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of a germin-like protein gene expressed in somatic and zygotic embryos of pine (Pinus caribaea Morelet) (1998)
    Springer
    Plant molecular biology 38 (1998), S. 1179-1190 
    Details
    ISSN: 1573-5028
    Keywords: apoplast ; cDNA cloning ; conifer embryogenesis ; gene expression ; germin-like proteins ; Pinus caribaea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Germin-like proteins (GLPs) ionically bound to the walls of preglobular somatic embryos of Pinus caribaea Morelet are markers of this early developmental stage. In order to reveal the physiological implications of such markers during early embryo development, we isolated a cDNA clone from somatic embryos predicted to encode a protein with sequence similarity to GLPs. PcGER1 has an open reading frame corresponding to a 220 amino acid polypeptide with a putative N-glycosylation site on Asn-69. The presence of a 24 amino acid putative signal peptide supports the hypothesis of an apoplastic location. The N-terminal 20 amino acid sequence of the predicted mature protein is identical to the amino terminal sequence of GP111, one of the extracellular pine GLPs previously identified. Southern blot hybridizations indicate that PcGER1 is probably unique in the pine genome. Transcripts homologous to PcGER1 are abundant in all embryogenic lines, absent from nonembryogenic lines, and present in quiescent zygotic embryos but not in the female gametophyte, the haploid storage tissue of conifers. Their abundance sharply decreases during germination. Isolation of gf-0.8, a genomic fragment identical to PcGER1 cDNA sequence, confirms that no introns disrupt the coding region as it has been already described for wheat gf-2.8 and gf-3.8 genomic clones. Recombinant PcGER1, produced in Escherichia coli, is recognized by antibodies raised against the GP111 N-terminal nonapeptide and the unglycosylated wheat germin monomer. The implications of GLPs in pine embryogenesis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006033622928
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  • 10
    Electronic Resource
    Electronic Resource
    Potential of somatic embryogenesis in Prunus avium immature zygotic embryos (1993)
    Springer
    Plant cell, tissue and organ culture 34 (1993), S. 209-215 
    Details
    ISSN: 1573-5044
    Keywords: immature cotyledons ; morphogenic response ; Rosaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For the purpose of developing somatic embryogenesis in Prunus avium L., immature zygotic embryos, collected from five donor trees and sorted into two size classes (C1: 2.5–3.5 and C2: 3.6–4.5 mm), received various experimental treatments. When cultured for 10 days on an inductive medium containing 18.1 μM 2,4-dichlorophenoxyacetic acid (2,4-d) and 9.3 μM kinetin, then transferred to fresh medium without growth regulators, 2.5% of the C1 class cotyledons expressed direct somatic embryogenesis. C2 class cotyledons were less responsive. The response was also influenced by the chosen donor tree. In a few cases, spontaneous germination occurred. The presence of a root meristem was clearly demonstrated by histological examination of longitudinal sections. The replacement of half the amount of 2,4-d, present in the inductive medium mentioned above, by the same quantity of naphthaleneacetic acid reduced the incidence of somatic embryogenesis. Conversely, a rhizogenic response was strongly enhanced. When submitted to an inductive medium containing indoleacetic acid and zeatin without any subcultures for 3 months, C1 class cotyledons were the most morphogenic and developed leaves and cotyledon-like structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00036104
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