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  • 1
    Electronic Resource
    Electronic Resource
    Overproduction of salicylic acid in plants by bacterial transgenes enhances pathogen resistance (2000)
    [s.l.] : Nature America Inc.
    Nature biotechnology 18 (2000), S. 779-783 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] After a hypersensitive response to invading pathogens, plants show elevated accumulation of salicylic acid (SA), induced expression of plant defense genes, and systemic acquired resistance (SAR) to further infection by a broad range of pathogens. There is compelling evidence that SA plays a crucial ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/77347
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  • 2
    Electronic Resource
    Electronic Resource
    The distribution of strictosidine-synthase activity and alkaloids in Cinchona plants (1991)
    Springer
    Planta 183 (1991), S. 536-541 
    Details
    ISSN: 1432-2048
    Keywords: Alkaloid localization ; Cinchona ; Stristosidine synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relation between the total alkaloid content and the activity of strictosidine synthase (EC 4.3.3.2), a key enzyme in alkaloid biosynthesis, was studied in distinct parts of six-month-old plants of Cinchona ledgeriana Moens. Strictosidine-synthase activity was present in the tops of the stems, including the young developing leaflets, and in the roots. The highest alkaloid contents of the plant were also found in these parts; however, the types of alkaloids differed, cinchophyllines being present in the aerial parts and quinoline alkaloids in the roots. In the stem and in old leaves, both strictosidine-synthase activity and alkaloid content were low. These results indicate that in young Cinchona plants the alkaloids are mainly synthesized in the axial extremities of the plant and that they are stored at the site of their synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194275
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  • 3
    Electronic Resource
    Electronic Resource
    Detrimental effects ofCinchona leaf alkaloids on larvae of the polyphagous insectSpodoptera exigua (1992)
    Springer
    Journal of chemical ecology 18 (1992), S. 1955-1964 
    Details
    ISSN: 1573-1561
    Keywords: Chemical defense ; Cinchona ; indole alkaloids ; leaf alkaloids ; Lepidoptera ; Noctuidae ; quinoline alkaloids ; root alkaloids ; Spodoptera exigua
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract YoungCinchona ledgeriana plants contain two types of alkaloid: indole alkaloids in the leaves and quinoline alkaloids in the root. FromCinchona leaves, a crude alkaloid extract was made, containing the cinchophylline type of indole alkaloids and a small amount of 5-methoxytryptamine. The leaf alkaloid extract exerted a strong detrimental effect on the growth of larvae of the polyphagous beet armyworm,Spodoptera exigua (Lepidoptera). Feeding of larvae on an artificial diet containing the leaf alkaloids at the same concentrations as those found in the plant resulted in significant growth reduction, retardation in development, and mortality of the larvae. Cinchophyllines are composed of 5-methoxytryptamine coupled to a corynantheal unit. When incorporated into the artificial diet, 5-methoxytryptamine alone had no effect on the 5.exigua larvae. Corynantheal, however, had a strong detrimental effect on growth of the larvae, its effect being comparable to that of the leaf alkaloid extract. In contrast to the indole-type leaf alkaloids, the quinolinetypeCinchona root alkaloids did not affect growth and development of the larvae. These results suggest that the indole-type alkaloids, which inCinchona plants are present at the highest concentrations in the young, vulnerable leaflets, are involved in the chemical defense of the plant against herbivorous insects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00981919
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  • 4
    Electronic Resource
    Electronic Resource
    Involvement of strictosidine as a defensive chemical inCatharanthus roseus (1996)
    Springer
    Journal of chemical ecology 22 (1996), S. 1355-1366 
    Details
    ISSN: 1573-1561
    Keywords: Antifeedant ; fungi ; bacteria ; Spodoptera exigua ; Catharanthus roseus ; Fusarium solani ; Fusarium oxysporum ; Trichoderma viride ; Cladosporium cucumerinum ; Phytophthora infestans ; strictosidine ; strictosidine glucosidase ; indole alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The involvement of the glucoalkaloid strictosidine in antimicrobial and antifeedant activity inCatharanthus roseus leaves was investigated. Strictosidine and its deglucosylation product, specifically formed by the enzyme strictosidine glucosidase, were shown to be active against several microorganisms. In contrast, neither the intact glucoside, nor the aglycone product(s) was found to exhibit antifeedant activity againstSpodoptera exigua larvae, as was found for intactC. roseus leaves and leaf extracts. Besides alkaloids further downstream in the biosynthesis pathway, a more apolar, yet unidentified compound may be involved in this activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02027718
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  • 5
    Electronic Resource
    Electronic Resource
    Identification of UV-B light-responsive regions in the promoter of the tryptophan decarboxylase gene from Catharanthus roseus (1999)
    Springer
    Plant molecular biology 41 (1999), S. 491-503 
    Details
    ISSN: 1573-5028
    Keywords: Catharanthus roseus ; Str Tdc ; terpenoid indole alkaloids ; UV light
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The tryptophan decarboxylase (Tdc) gene encodes a key enzyme in the biosynthesis of terpenoid indole alkaloids (TIAs) in Catharanthus roseus. TIAs absorb ultraviolet light (UV) and putative functions in plants include a role as UV protectants. In support of this possible function we demonstrate here that UV light induces accumulation of several TIAs as well as expression of the Tdc gene in C. roseus. In addition, in tobacco a Tdc-gusA construct was found to be specifically induced by UV-B light. Lack of induction by UV-A or other wavelengths of light indicate that Tdc expression is regulated by a specific UV-B receptor and corresponding signal transduction pathway. To identify UV-responsive Tdc promoter elements, a loss-of-function analysis was performed, in which deletion derivatives were fused to the gusA reporter gene and analysed in transgenic tobacco plants. Truncation of the Tdc promoter from −1818 (relative to the start of transcription) to −160 reduced expression levels two-fold without affecting the qualitative UV response. Deletion to −37 further reduced expression levels five-fold, but the Δ37 promoter also remained UV-responsive. Subsequently, the −160 to −37 region was further studied by gain-of-function experiments, in which the transcriptional activities of tetramerized subfragments fused to truncated promoters were analysed. Combination of the data identified several functional regions in the −160 to +198 promoter. The −160 to −99 region acts as the main transcriptional enhancer. UV-responsive elements appeared to be redundant in the −160 Tdc promoter and to reside between −99 and −37 and between −37 and +198.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006321100550
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  • 6
    Electronic Resource
    Electronic Resource
    Overexpression of a tryptophan decarboxylase cDNA inCatharanthus roseus crown gall calluses results in increased tryptamine levels but not in increased terpenoid indole alkaloid production (1995)
    Springer
    Transgenic research 4 (1995), S. 315-323 
    Details
    ISSN: 1573-9368
    Keywords: Catharanthus roseus ; tryptophan decarboxylase ; terpenoid idole alkaloids ; tdc cDNA overexpression ; crown gall calluses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The enzyme tryptophan decarboxylase (TDC) (EC 4.1.1.28) catalyses a key step in the biosynthesis of terpenoid indole alkaloids inC. roseus by converting tryptophan into tryptamine. Hardly anytdc mRNA could be detected in hormone-independent callus and cell suspension cultures transformed by the oncogenic T-DNA ofAgrobacterium tumefaciens. Supply of tryptamine may therefore represent a limiting factor in the biosynthesis of alkaloids by such cultures. To investigate this possibility, chimaeric gene constructs, in which atdc cDNA is linked in the sense or antisense orientation to the cauliflower mosaic virus 35S promoter and terminator, were introduced inC. roseus cells by infecting seedlings with an oncogenicA. tumefaciens strain. In the resulting crown gall tumour calluses harbouring thetdc sense construct, an increased TDC protein level, TDC activity and tryptamine content but no significant increase in terpenoid indole alkaloid production were observed compared to empty-vector-transformed tumour calluses. In tumour calluses containing thetdc antisense construct, decreased levels of TDC activity were measured. Factors which might be responsible for the lack in increased terpenoid indole alkaloid production in thetdc cDNA overexpressing crown gall calluses are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01972528
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