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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 97 (1996), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The relationship between seed phenolics and appearance of seed coat–imposed dormancy during seed development in Cynoglossum officinale L. was studied. Up to 24 days after anthesis, seeds failed to germinate upon imbibition in Petri dishes at 25°C. At 44 days after anthesis, seeds were fully germinable; removal of seed coats did not improve their germination or O2 uptake. At 72 days after anthesis, mature seeds at the base of the cyme did not germinate unless their coats were removed. Removal of seed coat also stimulated O2 uptake at this harvest date. The methanol-soluble phenolic content of the seeds increased during the early stages of seed development, in both the seed coat and the embryo. As seed development continued, the methanol-soluble phenolic content of the embryo stabilized, but that of the seed coat declined. This decline was associated with an increase in the thioglycolic acid–soluble phenolics, presumably lignins, in the seed coat. These results suggest that polymerization of methanol–soluble phenolics into lignins in the seed coat during later stages of seed development renders the seed coat of C. officinale impermeable to 03, and thus keeps the seed dormant.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science, Ltd
    Plant, cell & environment 25 (2002), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Plant cells respond to ultraviolet radiation and other oxidant-generating agents by mobilizing cellular defences, but the signal network linking perception of redox perturbation with defence remains unknown. Irradiation of tobacco suspension-cultured cells with UVC was found to induce the activation of a specific MAPK46 (salicylic acid-induced protein kinase) within 1 min. To explore where UVC and other oxidants might initially act to trigger this signal response, we employed suramin, a non-membrane-permeable reagent that interferes with membrane receptor-mediated signalling in mammalian cells. Pre-treatment of tobacco cells with suramin strongly attenuated the UVC-induced activation of MAPK46 in a concentration-dependent manner. Suramin was also able to interdict both ozone- and hydrogen peroxide-induced activation of MAPK46, indicating that reactive oxygen species (ROS) signalling to the MAPK cascade in general may be initiated at the cell membrane, perhaps through oxidative activation of membrane receptors.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of various macronutrients on growth and RA formation in cell suspension cultures of Anchusa officinalis has been investigated. Factors tested included sucrose concentration, alternate carbon sources, nitrate, phosphate and calcium concentration. The optimum concentration of sucrose was 3%. Fructose, glucose or their 1:1 mixture were also suitable carbon sources. The optimum concentrations of nitrate (15 mM), phosphate (3 mM) and calcium (0.25 mM) were, respectively, 3/5, 3x, and 1/4 those in normal B5 medium, when tested separately. These concentrations improved not only the yield of RA but also cell growth to a similar degree (10%–50%). Studies on the combined effects of these optimum macronutrient concentrations in B5 medium showed that RA production is inhibited by 2,4-D-containing revised medium but stimulated by NAA-containing revised medium.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell suspension cultures of Anchusa officinalis required exogenous phytohormones for their normal growth. Cell lysis was observed at the third passage in a hormone-free medium. Using hormone — depleted cells, the effects of auxins (2,4-D, NAA, IAA and CFP) and cytokinins (BA, kinetin, and zeatin) on cell growth and RA production were investigated. All auxins tested could maintain growth and integrity of the cells whereas cytokinins alone could not, suggesting that this culture is auxindependent. Among the auxins tested, NAA had a pronounced effect on RA production. The total RA content obtained at optimum NAA concentration (0.25 mg/l) reached 1.7 g/l (12% of dry weight). The kinetics of growth and RA production suggested that the increase in final RA content was due to both an increase in the rate of RA synthesis and initiation of the period of synthesis in the exponential rather than the linear growth phase.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Planta 111 (1973), S. 113-118 
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ten species of plants from 8 families, grown as sterile cell cultures, were examined for their ability to degrade the aromatic ring of l-tyrosine and two of its metabolites, homogentisic acid and 3,4-dihydroxyphenylalanine (DOPA). All cultures showed low levels of tyrosine degradation (0.3–2.6% in 24 h) and high levels of homogentisic acid degradation (9.3–31.0% in 24 h). Cultures of Amaranthus caudatus L. resembled the other nine species in possessing a moderate capacity for DOPA degradation (0.3–11.1% in 24 h).
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Planta 137 (1977), S. 287-291 
    ISSN: 1432-2048
    Keywords: Cell culture ; Coleus ; Rosmarinic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell suspension cultures of Coleus blumei Benth. have been found to accumulate 8–11% of their dry weight as rosmarinic acid (α-O-caffeoyl-3,4-dihydroxyphenyl-lactic acid). Actively-growing tissue converts 〉20% of exogenously supplied phenylalanine and tyrosine to the caffeoyl ester and this high rate of synthesis coincides with an increase in phenylalanine ammonia-lyase specific activity. Administration to the cultures of known phenylpropanoid precursors of rosmarinic acid failed to enhance the latter's production and in some cases inhibited it.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2048
    Keywords: Coleus ; Phenylalanine ammonia-lyase ; Rosmarinic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phenylalanine ammonia-lyase from an “over-producer” strain of Coleus blumei Benth. cell cultures accumulating high levels of rosmarinic acid (RA) has been shown to possess no special feed-back sensitivity to RA or its precursors. No tyrosine-3-hydroxylase activity could be detected in culture extracts and no specific inhibitors of tyrosine incorporation into RA were found. L-α-aminooxy-β-phenyl propionic acid, however, was effective in specifically blocking phenylalanine incorporation. This block also led to an accumulation of label from tyrosine in 4-hydroxyphenyllactic acid rather than in 3,4-dihydroxyphenylalanine (DOPA) or 3,4-dihydroxyphenyllactic acid. These observations require a re-evaluation of the possible role of DOPA as a major biogenic precursor to RA.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2048
    Keywords: l-α-Aminooxy-β-phenylpropionate ; Syringa ; α-Fluoromethyl analogues ; Hordeum (enzyme inhibition) ; Tyrosine decarboxylase ; Verbascoside
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tyrosine decarboxylase (EC 4.1.1.25) from Syringa vulgaris L. cell cultures and from Hordeum vulgare L. seedlings is strongly inhibited by the phenylalanine analogue, l-α-aminooxy-β-phenylpropionate. l-α-Aminooxy-β-phenylpropionate is therefore not specific in its inhibitory action against phenylalanine ammonia-lyase (EC 4.3.1.5). Hordeum tyrosine decarboxylase is also very sensitive to α-fluoromethyl(3,4-dihydroxyphenyl)alanine, but preparations from Nicotiana tabacum L. and Sanguinaria canadensis L. are largely unaffected by either type of inhibitor.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1615-6102
    Keywords: Synthesis ; Vascular coating ; Tomato ; Verticillium albo-atrum ; L-α-aminooxy-β-phenylpropionate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Massive infusion of conidia ofVerticillium albo-atrum into the xylem of tomato induces a cell wall coating response in resistant and susceptible near-isolines. In the early stages two types of coating material develop in the xylem vessels. The first, designated type A, is formed in association with xylem parenchyma cells that lack secondary walls; the localized accumulation of type A coating in the in the adjacent intercellular spaces, primary walls (i.e., pit membranes) and vessels occurs in conjunction with localized development of apposition wall layers within the parenchyma cells. Type B coating is initially formed in association with xylem parenchyma cells with secondary walls; the localized accumulation of typeB coating in the adjacent intercellular spaces, primary walls (i.e., pit membranes) and vessels occurs in conjunction with development of protective layers within the parenchyma cells. Most vessels are surrounded by a number of parenchyma cells including both cell types; therefore, in most vessels the coatings are mixed in later stages of development (i.e.,〉 48 hours). The formation of both types of coating is stopped by the application of L-α-aminooxy-β-phenylpropionate, a specific inhibitor of phenylpropanoid synthesis. Histochemically, type A coating resembles lignin and type B, suberin. The data suggest that the coating response is due, wholly or in part to hypersecretion and/or chemical modification of normal cell wall components, induced by the pathogen.
    Type of Medium: Electronic Resource
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