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  • 1
    Electronic Resource
    Electronic Resource
    Differential patterns of phytoalexin accumulation and enzyme induction in wounded and elicitor-treated tissues ofPhaseolus vulgaris (1982)
    Springer
    Planta 154 (1982), S. 156-164 
    Details
    ISSN: 1432-2048
    Keywords: Chalcone synthase ; Colletotrichum ; Elicitor ; Phaseolus ; Phenylalanine ammonia-lyase ; Phytoalexin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In wounded cotyledons ofPhaseolus vulgaris L. the accumulation of the 5-hydroxy isoflavonoids kievitone and 2′-hydroxygenistein precedes the major increases in the levels of the 5-deoxy compounds phaseollin and coumestrol. Increased phytoalexin levels are preceded by transient increases in the extractable activities of L-phenylalanine ammonia-lyase (EC 4.3.1.5.), chalcone synthase and chalcone isomerase (EC 5.5.1.6.). Accumulation of phytoalexins, above wounded control levels, is observed following treatment of excised cotyledons or hypocotyls with crude or fractionated elicitor preparations heat-released from the cell walls ofColletotrichum lindemuthianum. Chalcone synthase levels are also induced in cotyledons, although crude elicitor and all fractions suppress L-phenylalanine ammonia-lyase activity in both tissues. Kievitone is the major phytoalexin induced in cotyledons, whereas in hypocotyls phaseollin predominates. Patterns of phytoalexin accumulation have been studied in response to varying concentrations of the crude and fractionated elicitor; 5-hydroxy isoflavonoid accumulation is highly dependent upon elicitor concentration, the dose-response curves for kievitone accumulation showing maxima at around 1 μg glucose equivalents per cotyledon, minima at 2–3 μg equivalents and increasing induction at higher concentrations. Similar patterns are observed for L-phenylalanine ammonia-lyase and chalcone synthase levels, although the overall extent of these changes is masked by the high wound response. Accumulation of 5-deoxy isoflavonoids above control levels requires high elicitor concentrations; no experimental conditions were found under which phaseollin accumulated to higher levels than kievitone in cotyledons during the first 48 h after elicitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387910
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Elicitor-mediated induction of chalcone isomerase in Phaseolus vulgaris cell suspension cultures (1983)
    Springer
    Planta 159 (1983), S. 561-569 
    Details
    ISSN: 1432-2048
    Keywords: Cell suspension culture ; Chalcone isomerase ; Elicitor ; Enzyme induction ; Phaseolus (chalcone isomerase) ; Phytoalexin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Approximately fourfold increases in the extractable activity of the enzyme chalcone isomerase (CHI, EC 5.5.1.6) were observed within 24 h of treatment of cell suspension cultures of Phaseolus vulgaris with a crude elicitor preparation heatreleased from the cell walls of the bean pathogen Colletotrichum lindemuthianum. The induction of CHI activity was highly dependent upon elicitor concentration, with maximum induction occurring in two discrete concentration ranges. A basal half-life for CHI〉32 h in control cultures was determined by labelling with 2H from 2H2O followed by analysis of the equilibrium distribution of enzyme activity in CsCl density gradients. Comparative density labelling indicated that at both the lower and higher effective elicitor concentrations, the induced appearance of CHI activity was the result of an apparent initial activation of pre-existing enzyme followed by an increase in the rate of de-novo synthesis of the enzyme as compared with non-elicited controls. The increased appearance of the enzyme over the first 8 h in elicitor-treated cultures was inhibited by cycloheximide, cordycepin and actinomycin D. The results are discussed in relation to the mechanisms of co-ordinate enzyme induction operating in French-bean cell cultures exposed to fungal elicitors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409146
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Glutathione and elicitation of the phytoalexin response in legume cell cultures (1991)
    Springer
    Planta 184 (1991), S. 403-409 
    Details
    ISSN: 1432-2048
    Keywords: Cell culture (phytoalexin response) ; Elicitation ; Glutathione ; Isoflavonoid phytoalexins ; Medicago ; Phytoalexin ; Phaseolus (phytoalexin response)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Both reduced glutathione (GSH) and oxidized glutathione elicited the phytoalexin response in cell-suspension cultures of bean (Phaseolus vulgaris L.) but had no effect in those of alfalfa (Medicago sativa L.). In bean cells, homoglutathione (HGSH) was the predominant soluble thiol and treatment of cells with fungal elicitor resulted in the accumulation of HGSH but not GSH. In contrast, GSH was more abundant than HGSH in unelicited alfalfa cells, and the intracellular levels of both thiols increased in response to fungal elicitor. Treatment of bean or alfalfa cells with l-oxothiazolidine-4-carboxylate, an artificial precursor for GSH biosynthesis, increased intracellular thiols in an analogous manner to that observed following treatment with fungal elicitor, but did not result in elicitation of the cultures. Differences were observed in the initial metabolic fates of exogenously supplied [35S]GSH in bean and alfalfa, but our data do not yet provide a basis for explaining how GSH acts as an elicitor. We conclude that the changes observed in intracellular thiols following exposure of cells to fungal elicitor are a consequence rather than a cause of the initial elicitation signal(s).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195343
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Stress responses in alfalfa (Medicago sativa L.) III. Induction of medicarpin and cytochrome P450 enzyme activities in elicitor-treated cell suspension cultures and protoplasts (1990)
    Springer
    Plant cell reports 9 (1990), S. 38-41 
    Details
    ISSN: 1432-203X
    Keywords: Medicago sativa L. ; Cytochrome P450 ; Elicitor ; Phytoalexin ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cell suspension cultures of alfalfa (Medicago sativa L.) accumulated phenolic secondary metabolites in a pattern similar to that seen in alfalfa roots. Upon treatment with a crude elicitor preparation from the bean pathogen Colletotrichum lindemuthianum, the pterocarpan phytoalexin medicarpin accumulated in cells and culture medium. The extractable activities of six enzymes involved in medicarpin biosynthesis (including three cytochrome P450 activities) were induced by treatment with elicitor, and their induction kinetics correlated with the rate of medicarpin accumulation. However, protoplasts prepared from these cultures accumulated neither medicarpin nor other secondary products after treatment with elicitor. The cytochrome P450 activities were induced during the preparation of the protoplasts, but could be further induced by treatment with fungal elicitor. The results are discussed in relation to the use of alfalfa protoplasts as a system for functional analysis of cloned defense genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232132
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    Paper (German National Licenses)
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