| Title: | Tuning the herbivore-induced ethylene burst: the role of transcript accumulation and ethylene perception in Nicotiana attenuata |
| Author(s): | von Dahl CC; Winz RA; Halitschke R; Kuhnemann F; Gase K; Baldwin IT; |
| Address: | "Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knoll-Strasse 8, Jena, Germany" |
| DOI: | 10.1111/j.1365-313X.2007.03142.x |
| ISSN/ISBN: | 0960-7412 (Print) 0960-7412 (Linking) |
| Abstract: | "Caterpillar-induced ethylene emissions play an important role in plant-herbivore interactions. The ethylene burst that ensues after attack exceeds wound-induced ethylene emissions, but the mechanisms responsible remain unknown. Adding larval oral secretions (OS) to wounds mimics this ethylene burst. We demonstrate that fatty acid-amino acid conjugates are the responsible elicitors in Manduca sexta OS, and identify genes that are important in OS-elicited ethylene biosynthesis and perception in the larvae's host, Nicotiana attenuata, by examining the consequences of gene silencing on OS-elicited ethylene emissions, as quantified by photo-acoustic spectroscopy. OS elicitation increased transcript accumulation of ACC synthase (ACS), virus-induced gene silencing of ACS halved the OS-elicited ethylene release, and ACC supplementation to ACS-silenced plants restored ethylene emissions, demonstrating that ACS activity limits the rate of release. Silencing three wound- or OS-elicited ACC oxidase (ACO) genes with an ACO consensus fragment abolished the OS-elicited ethylene release. Virus-induced gene silencing of each ACO individually revealed that only NaACO2a and NaACO3 regulate the OS-elicited ethylene release. Transforming plants with various etr1-1 constructs rendered them differentially 'deaf' to ethylene, and dramatically increased the OS-elicited ethylene burst, largely without regulating the transcripts of biosynthetic genes. The volume of the OS-elicited ethylene 'scream' was proportional to the plant's deafness, as determined by 1-MCP treatments. We conclude that the OS-elicited ethylene burst is tuned by a tag-team of transcriptional responses and ethylene perception. Ethylene signaling is shown to be essential in regulating two traits that are important in the N. attenuata-M. sexta interaction: OS-induced nicotine levels and floral longevity" |
| Keywords: | "Amino Acids, Cyclic/metabolism/pharmacology Animals Ethylenes/*metabolism Feeding Behavior Gene Expression Profiling *Gene Expression Regulation, Plant Gene Silencing Manduca/*physiology RNA, Plant/genetics/*metabolism Tobacco/*genetics/*metabolism *Trans;" |
| Notes: | "Medlinevon Dahl, Caroline C Winz, Robert A Halitschke, Rayko Kuhnemann, Frank Gase, Klaus Baldwin, Ian T eng Research Support, Non-U.S. Gov't England 2007/06/15 Plant J. 2007 Jul; 51(2):293-307. doi: 10.1111/j.1365-313X.2007.03142.x. Epub 2007 Jun 8" |
