Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants

Pankoke H, Dobler S (2015)
Physiological Entomology 40(1): 18-29.

Zeitschriftenaufsatz | Veröffentlicht | Englisch
 
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Autor*in
Pankoke, HelgaUniBi; Dobler, Susanne
Abstract / Bemerkung
Iridoid glycosides are plant defence compounds that are deterrent and/or toxic for unadapted herbivores but are readily sequestered by dietary specialists of different insect orders. Hydrolysis of iridoid glycosides by -glucosidase leads to protein denaturation. Insect digestive -glucosidases thus have the potential to mediate plant-insect interactions. In the present study, mechanisms associated with iridoid glycoside tolerance are investigated in two closely-related leaf beetle species (Coleoptera: Chrysomelidae) that feed on iridoid glycoside containing host plants. The polyphagous Longitarsus luridusScopoli does not sequester iridoid glycosides, whereas the specialist Longitarsus tabidusFabricius sequesters these compounds from its host plants. To study whether the biochemical properties of their -glucosidases correspond to the differences in feeding specialization, the number of -glucosidase isoforms and their kinetic properties are compared between the two beetle species. To examine the impact of iridoid glycosides on the -glucosidase activity of the generalist, L. luridus beetles are kept on host plants with or without iridoid glycosides. Furthermore, -glucosidase activities of both species are examined using an artificial -glucosidase substrate and the iridoid glycoside aucubin present in their host plants. Both species have one or two -glucosidases with different substrate affinities. Interestingly, host plant use does not influence the specific -glucosidase activities of the generalist. Both species hydrolyse aucubin with a much lower affinity than the standard substrate. The neutral pH reduces the -glucosidase activity of the specialist beetles by approximately 60% relative to its pH optimum. These low rates of aucubin hydrolysis suggest that the ability to sequester iridoid glycosides has evolved as a key to potentially preventing iridoid glycoside hydrolysis by plant-derived -glucosidases.
Stichworte
-glucosidase; specialist; Michaelis-Menten kinetics; iridoid glycosides; heat inactivation; gut pH; generalist; Aucubin; Chrysomelidae
Erscheinungsjahr
2015
Zeitschriftentitel
Physiological Entomology
Band
40
Ausgabe
1
Seite(n)
18-29
ISSN
0307-6962
Page URI
https://pub.uni-bielefeld.de/record/2719277

Zitieren

Pankoke H, Dobler S. Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants. Physiological Entomology. 2015;40(1):18-29.
Pankoke, H., & Dobler, S. (2015). Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants. Physiological Entomology, 40(1), 18-29. doi:10.1111/phen.12085
Pankoke, Helga, and Dobler, Susanne. 2015. “Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants”. Physiological Entomology 40 (1): 18-29.
Pankoke, H., and Dobler, S. (2015). Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants. Physiological Entomology 40, 18-29.
Pankoke, H., & Dobler, S., 2015. Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants. Physiological Entomology, 40(1), p 18-29.
H. Pankoke and S. Dobler, “Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants”, Physiological Entomology, vol. 40, 2015, pp. 18-29.
Pankoke, H., Dobler, S.: Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants. Physiological Entomology. 40, 18-29 (2015).
Pankoke, Helga, and Dobler, Susanne. “Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants”. Physiological Entomology 40.1 (2015): 18-29.
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