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Individual variability in herbivore-specific elicitors from the plant's perspective
Amy Roda1, Rayko Halitschke, Anke Steppuhn
1Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, Beutenberg Campus, D-07745, Jena, Germany.
Molecular Ecology
|July 13, 2004
Summary
Fatty acid-amino acid conjugates (FACs) in caterpillar regurgitant are key to plant defense responses. These compounds, found in Manduca sexta larvae, trigger specific plant defenses and transcriptional changes, demonstrating their necessity and sufficiency in modulating wound responses.
Area of Science:
- Plant-insect interactions
- Chemical ecology
- Molecular plant pathology
Background:
- Lepidopteran larval oral secretions significantly alter plant wound responses.
- Fatty acid-amino acid conjugates (FACs) are abundant in herbivore regurgitant and act as potential elicitors.
Purpose of the Study:
- To determine if specific FACs in Manduca sexta regurgitant are responsible for modulating Nicotiana attenuata wound responses.
- To investigate the role of FACs in direct and indirect plant defenses, jasmonic acid signaling, and transcriptional changes.
- To assess if Nicotiana attenuata differentiates between varying FAC chemotypes in regurgitant.
Main Methods:
- Detailed microarray analysis to assess transcriptional changes in response to FACs.
- Secondary metabolite analysis to quantify FACs in larval secretions and plant tissues.
- Creation of synthetic FAC blends to mimic natural chemotypes and application to plants.
Main Results:
- The two most abundant FACs in Manduca sexta regurgitant accounted for direct and indirect defenses, jasmonic acid burst, and 86% of induced transcriptional changes.
- FACs were present in larvae after their first meal, throughout the alimentary canal, and in frass, but not in salivary glands.
- Nicotiana attenuata plants did not differentiate between different FAC chemotypes, indicating a general response to FAC presence rather than specific ratios.
Conclusions:
- FACs are necessary and sufficient for Manduca-specific modulation of Nicotiana attenuata wound responses.
- Plant defense responses are tailored by FACs from feeding caterpillars, but plants do not distinguish between individual caterpillar chemotypes.
- This study elucidates the critical role of specific chemical elicitors in mediating plant-herbivore interactions.