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  • 1
    Electronic Resource
    Electronic Resource
    Incorporation of Acetate, Propionate, and Methionine into Rapamycin by Streptomyces hygroscopicus (1991)
    s.l. : American Chemical Society
    Journal of natural products 54 (1991), S. 167-177 
    Details
    ISSN: 1520-6025
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/np50073a015
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  • 2
    Electronic Resource
    Electronic Resource
    The isoflavonoid phytoalexin pathway: From enzymes to genes to transcription factors (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 93 (1995), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The pterocarpan phytoalexins of the Leguminosae are synthesized from L-phenyl-alanine via a minimum of 11 enzymatic steps involving the central phenylpropanoid pathway, three reactions of flavonoid biosynthesis, and the isoflavonoid branch pathway. The extractable activities of all these enyzmes, and of enzymes supplying precursors from primary metabolism, increase in response to fungal infection or exposure of plant cells to elicitor macromolecules isolated from the cell walls of yeast or plant pathogenic fungi. The involvement of reductases and cytochrome P450 hydroxylases places a high demand for NADPH on elicited cells. The NADPH is most likely supplied by activation of the pentose phosphate pathway. Genes or cDNAs encoding 7 of the enzymes involved in the synthesis of the phytoalexin medicarpin have been cloned from alfalfa and/or other species. Induction of enzyme activity results from transcriptional activation of the corresponding genes, leading to increased steady state levels of translatable mRNAs. This transcriptional activation is programmed through the interaction of sets of elicitor/infection-modulated transcription factors with their cognate cis elements in the promoters of the phytoalexin biosynthetic genes. Gene activation occurs through generation of intracellular signals which lead to modulation of transcription factor activity, through either increased synthesis of the factor(s), activation via reversible post-translational modification (e.g. phosphorylation/dephos-phorylation), translocation of factors from cytoplasm to nucleus, or combinations of these. Coordinated induction of the enzymes of phytoalexin synthesis may involve multiple signals and factors for transcriptional activation, as well as feedback and feed-forward fine controls at both transcriptional and post-transcriptional levels. In beneficial mycorrhizal interactions, induction of early pathway genes is uncoupled from that of later, phytoalexin-specific genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb02243.x
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  • 3
    Electronic Resource
    Electronic Resource
    Improvement of Natural Defense Responses (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 792 (1996), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1996.tb32499.x
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  • 4
    Electronic Resource
    Electronic Resource
    Features of the hmg 1 subfamily of genes encoding HMG-CoA reductase in potato (1995)
    Springer
    Plant molecular biology 28 (1995), S. 1-15 
    Details
    ISSN: 1573-5028
    Keywords: 3-hydroxy-3-methylglutaryl coenzyme A reductase ; gene family ; Solanum tuberosum ; isoprenoid metabolism ; cis-acting elements ; pollen expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) catalyzes a key step in isoprenoid metabolism leading to a range of compounds that are important for the growth, development and health of the plant. We have isolated 7 classes of genomic clones encoding HMGR from a potato genomic library. Comparison of nucleic acid sequences reveals a high degree of identity between all seven classes of clones and the potato hmg 1 gene described by Choi et al. (Plant Cell 4: 1333, 1992), indicating that all are members of the same subfamily in potato. A representative member (hmg 1.2) of the most abundant class of genomic clones was selected for further characterization. Transgenic tobacco and potato containing the β-glucuronidase (GUS) reporter gene under the control of the hmg 1.2 promoter expressed GUS activity constitutively at a low level in many plant tissues. High levels of GUS activity were observed only in the pollen. GUS assays of isolated pollen, correlations of GUS activity with the HMGR activity of anthers, hmg 1.2 promoter deletion studies, and segregation analysis of the expression of hmg 1.2::GUS among the R2 pollen of R1 progeny plants demonstrated that the hmg 1.2 promoter controls pollen expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042033
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  • 5
    Electronic Resource
    Electronic Resource
    Stress responses in alfalfa (Medicago sativa L.) 12. Sequence analysis of phenylalanine ammonia-lyase (PAL) cDNA clones and appearance of PAL transcripts in elicitor-treated cell cultures and developing plants (1991)
    Springer
    Plant molecular biology 17 (1991), S. 415-429 
    Details
    ISSN: 1573-5028
    Keywords: L-phenylalanine ammonia-lyase mRNA ; fungal elicitor ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An expression library containing cDNAs derived from transcripts from fungal elicitor-treated alfalfa cell suspension cultures was screened with an antiserum raised against phenylalanine ammonia-lyase (PAL) from alfalfa. A single immunoreactive clone was isolated which encoded a full-length PAL cDNA (APAL1) consisting of a 2175 bp open reading frame, 96 bp 5′-untranslated leader and 128 bp 3′-noncoding region. The deduced amino acid sequence was 86.5% similar to that of the PAL2 gene of bean, and encoded a polypeptide ofM r 78865. A second PAL cDNA species was isolated, whose 3′-untranslated region was 86% identical to that of APAL1. Southern blot analysis indicated that PAL is encoded by a small multigene family in alfalfa. PAL transcript levels were rapidly and massively induced, and preceded increased PAL extractable activity, on exposure of alfalfa suspension cells to elicitor from baker's yeast. PAL transcripts were most abundant in roots, stems and petioles during growth and development of alfalfa seedlings. These studies provide the basis for an examination of the developmental and environmental control of a key enzyme of phenylpropanoid synthesis in a plant species which is readily amenable to stable genetic transformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040636
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  • 6
    Electronic Resource
    Electronic Resource
    Stress responses in alfalfa (Medicago sativa L.) 11. Molecular cloning and expression of alfalfa isoflavone reductase, a key enzyme of isoflavonoid phytoalexin biosynthesis (1991)
    Springer
    Plant molecular biology 17 (1991), S. 653-667 
    Details
    ISSN: 1573-5028
    Keywords: fungal elicitor ; isoflavone reductase mRNA ; Medicago sativa ; phytoalexin biosynthesis ; stereochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The major phytoalexin in alfalfa is the isoflavonoid (−)-medicarpin (or 6aR, 11aR)-medicarpin. Isoflavone reductase (IFR), the penultimate enzyme in medicarpin biosynthesis, is responsible for introducing one of two chiral centers in (−)-medicarpin. We have isolated a 1.18 kb alfalfa cDNA (pIFRalf1) which, when expressed in Escherichia coli, converts 2′-hydroxyformononetin stereospecifically to (3R)-vestitone, as would be predicted for IFR from alfalfa. The calculated molecular weight of the polypeptide (35400) derived from the 954 bp open reading frame compares favorably to estimated M rs determined for IFR proteins purified from other legumes. The transcript (1.4 kb) is highly induced in elicited alfalfa cell cultures. The kinetics of induction are consistent with the appearance of IFR activity, the accumulation of medicarpin, and the observed induction of other enzymes in the pathway. Low levels of IFR transcripts were found in healthy plant parts (roots and nodules) which accumulate low levels of a medicarpin glucoside. IFR appears to be encoded by a single gene in alfalfa. The cloning of IFR opens up the possibility of genetic manipulation of phytoalexin biosynthesis in alfalfa by altering isoflavonoid stereochemistry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037051
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  • 7
    Electronic Resource
    Electronic Resource
    Reduced lignin in transgenic plants containing a caffeic acidO-methyltransferase antisense gene (1994)
    Springer
    Transgenic research 3 (1994), S. 120-126 
    Details
    ISSN: 1573-9368
    Keywords: lignification ; tobacco ; caffeic acid 3-O-methyltransferase ; antisense RNA ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lignin is a major structural polymer of secondarily thickended plant vascular tissue and fibres, imparting mechanical strength to stems and trunks and hydrophobicity to conducting vessels. Constitutive expression of a lucerne caffeic acid 3-O-methyltransferase antisense RNA in transgenic tobacco leads to a significant reduction in lignin content, particularly in the younger parts of the stems, without apparent alterations in lignin monomer composition. These observations open up the possibility of genetically manipulating plants with reduced lignin for improved processing and biomass digestibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974090
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  • 8
    Electronic Resource
    Electronic Resource
    An Introduction to the Biosynthesis of Chemicals Used in Plant-Microbe Communication (2000)
    Springer
    Journal of plant growth regulation 19 (2000), S. 131-143 
    Details
    ISSN: 1435-8107
    Keywords: Key words: Biosynthesis; Secondary metabolite; Natural products; Phytoalexin; Phenylpropanoid; Terpenoid; Alkaloid; Polyacetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plants accumulate a diverse array of natural products, which can serve either to defend the plant against various microbes in its environment or to attract various microbes, both beneficial and pathogenic. Plants must also attract pollinators, repel or poison herbivores, compete with other plant species, and protect themselves from environmental dangers such as high light intensities. Some compounds have been implicated in playing a role in multiple interactions. Although the structures vary immensely in size and complexity, most are derived from a limited number of core biosynthetic pathways. This review briefly summarizes the biosynthetic origins of phenylpropanoid (including simple phenolics, flavonoids, anthocyanins and isoflavonoids), polyacetate, terpenoid, and alkaloid classes of metabolites. Compounds reported to be important in plant-microbe, plant-animal, and plant-plant interactions will be given as examples of each of these classes. Other aspects of biosynthesis also will be discussed, including the timing or location of biosynthesis, the potential for genetic manipulation of these pathways, and various questions regarding the biosynthesis of these compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003440000016
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  • 9
    Electronic Resource
    Electronic Resource
    Regulation of isoflavonoid metabolism in alfalfa (1994)
    Springer
    Plant cell, tissue and organ culture 38 (1994), S. 213-220 
    Details
    ISSN: 1573-5044
    Keywords: Glomus versiforme ; isoflavone reductase ; medicarpin ; Medicago sativa ; phytoalexin ; Phoma medicaginis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isoflavonoids are believed to play important roles in plant-microbe interactions. During infection of alfalfa (Medicago sativa) leaves with the fungal pathogen Phoma medicaginis, rapid increases in mRNA levels and enzyme activities of isoflavone reductase, phenylalanine ammonia-lyase, chalcone synthase and other defense genes are observed within 1 to 2 hours. The phytoalexin medicarpin and its antifungal metabolite sativan increase beginning at 4 and 8 hours, respectively, along with other isoflavonoids. In contrast, during colonization of alfalfa roots by the symbiotic mycorrhizal fungus Glomus versiforme, expression of the general phenylpropanoid and flavonoid genes phenylalanine ammonia-lyase and chalcone synthase increases while mRNA levels for the phytoalexin-specific isoflavone reductase decrease. The total isoflavonoid content of colonized roots increases with time and is higher than that of uninoculated roots, but the accumulation of the antifungal medicarpin is somehow suppressed. An isoflavone reductase genomic clone has been isolated, promoter regions have been fused to the reporter gene β-glucuronidase, and the promoter-reporter fusions have been transformed into tobacco and alfalfa. Using histological staining, we have studied the developmental and stress-induced expression of this phytoalexin-specific gene in whole plants at a more detailed level than other methods allow. The isoflavone reductase promoter is functional in tobacco, a plant which does not synthesize isoflavonoids. Infection of transgenic alfalfa plants by Phoma causes an increase in β-glucuronidase staining, as does elicitation of transgenic alfalfa cell cultures, indicating that this promoter fusion is a good indicator of phytoalexin biosynthesis in alfalfa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033879
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  • 10
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    Induction of early mevalonate pathway enzymes and biosynthesis of end products in potato (Solanum tuberosum) tubers by wounding and elicitation (1996)
    Elsevier
    Details
    Publication Date: 1996-08-01
    Print ISSN: 0031-9422
    Electronic ISSN: 1873-3700
    Topics: Biology , Chemistry and Pharmacology
    Published by Elsevier
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