Skip Navigation



MBE Advance Access published online on August 29, 2003
Molecular Biology and Evolution, doi:10.1093/molbev/msg240
Molecular Biology and Evolution © Society for Molecular Biology and Evolution 2003; all rights reserved
This Article
Right arrow Advance Access manuscript (PDF) Freely available
Right arrow All Versions of this Article:
21/2/218    most recent
msg240v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Labeyrie, E.
Right arrow Articles by Dobler, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Labeyrie, E.
Right arrow Articles by Dobler, S.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Accepted August 6, 2003
© 2003 Society for Molecular Biology and Evolution

Original Articles

Molecular Adaptation of Chrysochus Leaf Beetles to Toxic Compounds in Their Food Plants

Estelle Labeyrie 1 and Susanne Dobler 1*

1 Institut für Zoologie, Universität Freiburg, Hauptstr. 1, 79104 Freiburg, Germany

* To whom correspondence should be addressed. E-mail: susanne.dobler{at}zoologie.uni-hamburg.de.


  Abstract

Herbivores that feed on toxic plants have to overcome plant defenses, and occasionally may even benefit from them. The current challenge is to understand how herbivores evolve the necessary physiological adaptations and which changes at the molecular level are involved. In this context we studied the leaf beetles genus Chrysochus (Coleoptera, Chrysomelidae). Two species of this genus, C. auratus and C. cobaltinus, feed on plants that contain toxic cardenolides. These beetles not only avoid poisoning by the toxin but they even use it for their own defense against predators. All other Chrysochus species feed on plants that are devoid of cardenolides. The most important active principle of cardenolides consists in their capacity to bind to and thereby block the ubiquitous Na+/K+-ATPase responsible for maintaining cellular potentials. By analyzing the DNA sequence of the putative ouabain binding site of the alpha-subunit of the Na+/K+-ATPase gene of Chrysochus and its close relatives feeding on plants with or without cardenolides we here trace the evolution of cardenolide insensitivity in this group of beetles. The most interesting difference among the sequences involves the amino acid at position 122: while all species that do not encounter cardenolides have an asparagine in this position, both Chrysochus species on cardenolide plants have a histidine instead. This single amino acid substitution has already been shown to confer cardenolide insensitivity in the Monarch butterfly. A mtDNA-based phylogeny corroborates the hypothesis that the asparagine at position 122 of the alpha-subunit of the Na+/K+-ATPase gene as observed in Drosophila and other insects is the plesiomorphic condition in this group of leaf beetles. The later host-plant switch to cardenolide-containing plants in the common ancestor of C. auratus and C. cobaltinus coincides with the exchange of the asparagine for a histidine in the ouabain binding site.

Key Words: Chrysochus, Na+/K+-ATPase alpha subunit, cardenolide, ouabain binding site


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.