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Preparing and Rearing Axenic Insects with Tissue Cultured Seedlings for Host-Gut Microbiota Interaction Studies of the Leaf Beetle
Published on: October 8, 2021
Beetles do it differently: two stereodivergent cyclisation modes in iridoid-producing leaf-beetle larvae
Maritta Kunert1, Peter Rahfeld, Kamel H Shaker
1Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, 07745 Jena, Germany.
Chembiochem : a European Journal of Chemical Biology
|January 24, 2013
Summary
Leaf beetle larvae produce chrysomelidial for defense. Different species exhibit distinct cyclization pathways and stereochemistry for this iridoid, revealing evolutionary divergence in chemical defense mechanisms.
Area of Science:
- Chemical Ecology
- Organic Chemistry
- Evolutionary Biology
Background:
- Larvae of Chrysomelina beetles synthesize the iridoid chrysomelidial for predator defense.
- Previous studies have indicated variations in chemical defense mechanisms among beetle species.
Purpose of the Study:
- To investigate the biosynthesis and stereochemistry of chrysomelidial in various Chrysomelina species.
- To elucidate the differences in cyclization pathways of the precursor 8-oxogeranial between the genus Gastrophysa and other related species.
Main Methods:
- Feeding experiments using deuterated precursors.
- In vitro isotope exchange experiments with defensive secretions.
- Gas chromatography-mass spectrometry (GC-MS) analysis on a chiral column to determine absolute configuration.
Main Results:
- Two distinct cyclization modes for 8-oxogeranial were identified: a Rauhut-Currier-type cyclization (transoid dienamine) in Phaedon cochleariae, Hydrothassa marginella, and Phratora vulgatissima, and a different pathway (cisoid dienamine) in Gastrophysa species.
- Stereochemical analysis revealed that H. marginella and P. vulgatissima produce (5S,8S)-chrysomelidial, while P. cochleariae and Gastrophysa species synthesize (5R,8R)-chrysomelidial.
Conclusions:
- The observed differences in cyclization pathways and resulting stereochemistry of chrysomelidial highlight evolutionary divergence in chemical defense strategies within the Chrysomelina family.
- These findings contribute to understanding the biochemical basis of insect chemical ecology and evolution.
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