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  • 1
    Electronic Resource
    Electronic Resource
    Activation of plant foliar oxidases by insect feeding reduces nutritive quality of foliage for noctuid herbivores (1989)
    Springer
    Journal of chemical ecology 15 (1989), S. 2667-2694 
    Details
    ISSN: 1573-1561
    Keywords: Polyphenol oxidase ; peroxidase ; digestibility reduction ; plant-insect interactions ; phenolic-protein binding ; chlorogenic acid ; Heliothis zea ; Spodoptera exigua ; Lepidoptera ; Noctuidae ; Lycopersicon esculentum ; host-plant resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The foliage and fruit of the tomato plantLycopersicon esculentum contains polyphenol oxidases (PPO) and peroxidases (POD) that are compartmentally separated from orthodihydroxyphenolic substrates in situ. However, when leaf tissue is damaged by insect feeding, the enzyme and phenolic substrates come in contact, resulting in the rapid oxidation of phenolics to orthoquinones. When the tomato fruitwormHeliothis zea or the beet army-wormSpodoptera exigua feed on tomato foliage, a substantial amount of the ingested chlorogenic acid is oxidized to chlorogenoquinone by PPO in the insect gut. Additionally, the digestive enzymes of the fruitworm have the potential to further activate foliar oxidase activity in the gut. Chlorogenoquinone is a highly reactive electrophilic molecule that readily binds cova-lently to nucleophilic groups of amino acids and proteins. In particular, the —SH and —NH2 groups of amino acids are susceptible to binding or alkylation. In experiments with tomato foliage, the relative growth rate of the fruitworm was negatively correlated with PPO activity. As the tomato plant matures, foliar PPO activity may increase nearly 10-fold while the growth rate of the fruitworm is severely depressed. In tomato fruit, the levels of PPO are highest in small immature fruit but are essentially negligible in mature fruit. The growth rate of larvae on fruit was also negatively correlated with PPO activity, with the fastest larval growth rate occurring when larvae fed on mature fruit. The reduction in larval growth is proposed to result from the alkylation of amino acids/protein byo-quinones, and the subsequent reduction in the nutritive quality of foliage. This alkylation reduces the digestibility of dietary protein and the bioavailability of amino acids. We believe that this mechanism of digestibility reduction may be extrapolatable to other plant-insect systems because of the ubiquitous cooccurrence of PPO and phenolic substrates among vascular plant species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01014725
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  • 2
    Electronic Resource
    Electronic Resource
    Potential role of lipoxygenases in defense against insect herbivory (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 651-666 
    Details
    ISSN: 1573-1561
    Keywords: Helicoverpa zea ; Lepidoptera ; Noctuidae ; lipoxygenase ; lipid peroxidation ; resistance ; herbivory ; soybean ; tomato ; cotton ; oxidative stress ; induced defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The potential role of the plant enzyme lipoxygenase in host resistance against the corn earwormHelicoverpa zea was examined. Lipoxygenase is present in most of the common host plants ofH. zea, with highest activity in the leguminous hosts such as soybean and redbean. Treatment of dietary proteins with linoleic acid and lipoxygenase significantly reduced the nutritive quality of soybean protein and soy foliar protein. Larval growth was reduced from 24 to 63% depending upon treatment. Feeding byH. zea on soybean plants caused damage-induced increases in foliar lipoxygenase and lipid peroxidation products. Larvae feeding on previously wounded plant tissue demonstrated decreased growth rates compared to larvae feeding on unwounded tissue. Midgut epithelium from larvae feeding on wounded tissues showed evidence of oxidative damage as indicated by significant increases in lipid peroxidation products and losses in free primary amines. The potential role of oxidative and nutritional stress as a plant defensive response to herbivory is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02059605
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  • 3
    Electronic Resource
    Electronic Resource
    Differential effect of tomatine and its alleviation by cholesterol on larval growth and efficiency of food utilization inHeliothis zea andSpodoptera exigua (1989)
    Springer
    Journal of chemical ecology 15 (1989), S. 387-398 
    Details
    ISSN: 1573-1561
    Keywords: Lepidoptera ; Noctuidae ; Heliothis zea ; Spodoptera exigua ; Lycopersicon esculentum ; tomato ; saponin ; glycoalkaloid ; tomatine ; cholesterol ; developmental sensitivity ; nutritional indices ; allelochemical interactions ; host-plant resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effect of tomatine on larval growth ofHeliothis zea andSpodoptera exigua was assessed by rearing larvae on diets with different concentrations of the chemical added. When reared from neonates, linear dose-response relationships were obtained for both species, withS. exigua being three times more sensitive to tomatine thanH. zea. Tomatine toxicity was completely alleviated inH. zea by the addition of equimolar cholesterol into the diet; however, inS. exigua some toxicity was maintained. Larvae ofS. exigua that were started on control diet were insensitive to tomatine after five days; larvae started on diet with an EC50 of tomatine and then switched to control diet after five days failed to recover from toxicosis. Larval growth ofH. zea, on the other hand, was affected both at the neonate and third-instar stage, but normal growth resumed when the larvae were transferred to control diet. Tomatine had little or no affect on food consumption, assimilation, or dietary utilization of the food by third-instar larvae ofS. exigua, except at a concentration 10 times the EC50. In contrast, the efficiency of food utilization ofH. zea larvae decreased with increasing tomatine concentrations. Assimilation of the food tended to increase, although not significantly, as tomatine levels increased. Food consumption ofH. zea larvae also increased when the tomatine concentration was greater than an EC50. The addition of equimolar cholesterol to diets with an EC50 of tomatine restored weight gain and nutritional indices values to control values. These results are related to the utility of using tomatine in host-plant resistance programs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02027799
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  • 4
    Electronic Resource
    Electronic Resource
    Avoidance of antinutritive plant defense: Role of midgut pH in Colorado potato beetle (1992)
    Springer
    Journal of chemical ecology 18 (1992), S. 571-583 
    Details
    ISSN: 1573-1561
    Keywords: Leptinotarsa decemlineata ; Coleoptera ; Chrysomelidae ; Colorado potato beetle ; Helicoverpa zea ; Lepidoptera ; Noctuidae ; phenolics ; poly-phenol oxidase ; peroxidase ; chlorogenic acid ; Lycopersicon esculentum ; tomato ; host-plant resistance ; midgut pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The fate of the tomato foliar phenolic, chlorogenic acid, in the digestive systems of Colorado potato beetleLeptinotarsa decemlineata (Coleoptera: Chrysomelidae) andHelicoverpa tea (Lepidoptera: Noctuidae) is compared. In larvalH. zea and other lepidopteran species previously examined, approximately 35–50% of the ingested chlorogenic acid was oxidized in the digestive system by foliar phenolic oxidases (i.e., polyphenol oxidase and peroxidase) from the tomato plant. The oxidized form of chlorogenic acid, chlorogenoquinone, is a potent alkylator of dietary protein and can exert a strong antinutritive effect upon larvae through chemical degradation of essential amino acids. In contrast, inL. decemlineata less than 4% of the ingested dose of chlorogenic acid was bound to protein. In vitro experiments to determine the influence of pH on covalent binding of chlorogenic acid to protein showed that 30–45% less chlorogenic acid bound to protein at pHs representative of the beetle midgut (pH 5.5–6.5) than at a pH representing the lepidopteran midgut (pH 8.5). At an acidic pH, considerably more of the alkylatable functional groups of amino acids (−NH2, −SH) are in the nonreactive, protonated state. Hence, polyphenol oxidases are unlikely to have significant antinutritive effects against the Colorado potato beetle and may not be a useful biochemical source of resistance against this insect. The influence of feeding by larval Colorado potato beetle on foliar polyphenol oxidase activity in tomato foliage and its possible significance to interspecific competition is also considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987820
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  • 5
    Electronic Resource
    Electronic Resource
    Interaction of nuclear polyhedrosis virus with catechols: Potential incompatibility for host-plant resistance against noctuid larvae (1987)
    Springer
    Journal of chemical ecology 13 (1987), S. 947-957 
    Details
    ISSN: 1573-1561
    Keywords: Heliothis zea ; Spodoptera exigua ; Noctuidae ; Lycoperiscon esculentum ; nuclear polyhedrosis virus ; chlorogenic acid ; rutin ; orthodihydroxy phenolics ; flavonoids ; host-plant resistance ; microbial control agents ; biological control ; antibiosis ; tomato ; pathogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Two major orthodihydroxy phenolics ofLycopersicon esculentum, rutin and chlorogenic acid, have previously been identified as potential sources of host-plant resistance against the tomato fruitwormHeliothis zea. We report here the possible incompatibility of these chemically based resistance factors with viral control ofH, zea. We have found that both rutin and chlorogenic acid significantly inhibited the infectivity of nuclear polyhedrosis viruses. Chlorogenic acid, when added to tissue culture medium containing TN-368 ovarian cells, inhibited the infectivity of a multiply embedded virus (AcMNPV) by over 86%. Rutin or chlorogenic acid, when fed toH. zea, inhibited the infectivity of a singly embedded nuclear polyhedrosis virus (HzSNPV), with the greatest degree of inhibition occurring at low doses of viral inoculum. Additionally, the ingestion of these phytochemicals significantly prolonged the survival time of virally infectedH. zea larvae. These results suggest that the effectiveness of nuclear polyhedrosis viruses in controllingH. zea populations may be adversely affected by varieties ofL. esculentum with significant levels (eg. 3.5 μmol/g wet weight) of rutin or chlorogenic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01020174
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