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  • 1
    Electronic Resource
    Electronic Resource
    Induced responses in three alkaloid-containing plant species (1993)
    Springer
    Oecologia 95 (1993), S. 425-430 
    Details
    ISSN: 1432-1939
    Keywords: Senecio jacobaea ; Cynoglossum officinale ; Catharanthus roseus ; Alkaloids ; Induced responses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper we test three plant species for the inducibility of their alkaloid production. The plants were heavily damaged by cutting off 50% of their leaf surface using a pair of scissors. The cut-off leaf tips were used as controls for possible diurnal fluctuations. After 3, 6, 12, 24 and 48 h, respectively, the leaf bases of the damaged plants were harvested and the alkaloid concentration was measured. In Senecio jacobaea the pyrrolizidine alkaloid (Pa) concentration in damaged plants decreased within 6–12 h after damage. Within 24 h after damage the Pa concentration of Cynoglossum officinale doubled compared to control values. Indole alkaloid production in Catharanthus roseus was found not to be induced in this experiment. The responses are discussed in a functional context. We hypothesize that the nature of the response is not a feature of the type of secondary metabolite, but is related to whether the plants are damaged mainly by generalist or by specialist herbivores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320998
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Genetic variation in constitutive and inducible pyrrolizidine alkaloid levels inCynoglossum officinale L. (1994)
    Springer
    Oecologia 99 (1994), S. 374-378 
    Details
    ISSN: 1432-1939
    Keywords: Cynoglossum officinale ; Pyrrolizidine alkaloids ; Induced defences ; Genetic variation ; Transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The constitutive pyrrolizidine alkaloid (PA) concentration of both shoots and roots differed significantly between 17 selfed families. The broad-sense heritability accounted for 33–43% of the variation in PA levels. Families also differed significantly in the amount and the direction of PA induction in both shoots and roots, 24 h after punching 15 holes in the leaves. We found a significantly negative relationship between the changes in PA content of the shoots and changes in PA content of the roots. The total PA content of the plants did not increase. We thus concluded that changes in PA distribution over the plant resulted from transport of PAs within the plant. The direction of transport differed between families: some transported PAs to the shoots, others to the roots. This makes it questionable whether PAs act as damage-induced defences. The effect of damage on the PA concentration is far less than the differences found between families in the constitutive PA concentration. This again strongly suggests that damage-induced defences inCynoglossum officinale do not play an important role. We argue that the general lack of attention that is given to genotype in induction experiments, has led to false conclusions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00627751
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Biological Activity of Datura wrightii Glandular Trichome Exudate Against Manduca Sexta Larvae (1998)
    Springer
    Journal of chemical ecology 24 (1998), S. 1529-1549 
    Details
    ISSN: 1573-1561
    Keywords: Tobacco hornworm ; Solanaceae ; insect–plant interactions ; glandular trichomes ; exudate ; resistance polymorphism ; oviposition choice ; acyl sugar esters ; Lepidoptera ; Sphingidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Natural populations of Datura wrightii in southern California consist of two distinctly different phenotypes. The leaves of one phenotype are densely covered with nonglandular trichomes and feel velvety. The other phenotype is covered with larger type IV glandular trichomes that excrete a sticky exudate. Neonate larvae of M. sexta reared on velvety leaves developed significantly faster than larvae on sticky leaves. Larvae on sticky leaves took 28% longer to reach the prepupal stage. Survival and pupal weight were not significantly different between the two groups. First instars of M. sexta had a significantly higher consumption rate on velvety leaves than on sticky leaves. Removal of the exudate from stickly leaves significantly increased larval consumption rates compared to unwashed controls. Female moths did not show an oviposition preference; both in the lab and in the field the two trichome phenotypes of D. wrightii received similar egg loads. Because there were no significant differences in other nutritional factors between the two plant phenotypes, we concluded that the exudate was responsible for the effect. We isolated a complex mixture of sugar esters (SE) as the biologically active compounds in the exudate of D. wrightii. The SE mixture was composed of glucose esterified with several combinations of straight chain C6–C9 acids. By comparing GC-MS spectra of synthetic SE with the SE extracted from D. wrightii, we identified one of the SE as 3′-O-hexanoyl glucose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020963817685
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  • 4
    Electronic Resource
    Electronic Resource
    The “Raison D'être” of pyrrolizidine alkaloids inCynoglossum officinale: Deterrent effects against generalist herbivores (1995)
    Springer
    Journal of chemical ecology 21 (1995), S. 507-523 
    Details
    ISSN: 1573-1561
    Keywords: Cynoglossum officinale ; Boraginaceae ; pyrrolizidine alkaloids ; chemical defense ; specialist herbivores ; generalist herbivores ; Ethmia bipunctella ; Mogulones (Ceutorhynchus) cruciger ; Spodoptera exigua ; Helix aspersa ; Frankliniella occidentalis ; Locusta migratoria ; Lyriomyza trifolii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In this study we tested whether pyrrolizidine alkaloids (PAs) ofCynoglossum officinale serve as antifeedants against herbivores. Total PA N-oxide extracts of the leaves significantly deterred feeding by generalist herbivores. Specialist herbivores did not discriminate between food with high and low PA levels. Three PAs fromC. officinale, heliosupine, echinatine, and 3′-acetylechinatine, equally deterred feeding by the polyphagous larvae ofSpodoptera exigua. Although the plants mainly contain PAs in their N-oxide form, reduced PAs deterred feeding byS. exigua more efficiently than PA N-oxides. On rosette plants, the monophagous weevilMogulones cruciger significantly consumed more of the youngest leaves, which had the highest PA level and the highest nitrogen percentage. Larvae ofEthmia bipunctella, which are oligophagous within the Boraginaceae, did not discriminate between leaves. All generalist herbivores tested significantly avoided the youngest leaves with the highest PA levels. In the field, the oldest leaves also were relatively more damaged by herbivores than the youngest leaves. It is hypothesized that the skewed distribution of PAs over the leaves of rosette plants reflects optimal defense distribution within the plant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02033698
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    Paper (German National Licenses)
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