Systemin Regulates Both Systemic and Volatile Signaling in Tomato Plants
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The prevailing reaction of plants to pest attack is the activation of various defense mechanisms. In tomato, several studies indicate that an 18 amino acid (aa) peptide, called systemin, is a primary signal for the systemic induction of direct resistance against plant-chewing pests, and that the transgenic expression of the prosystemin gene (encoding the 200 aa systemin precursor) activates genes involved in the plant response to herbivores. By using a combination of behavioral, chemical, and gene expression analyses, we report that systemin enhances the production of bioactive volatile compounds, increases plant attractivity towards parasitiod wasps, and activates genes involved in volatile production. Our data imply that systemin is involved in the systemic activation of indirect defense in tomato, and we conclude that a single gene controls the systemic activation of coordinated and associated responses against pests.
KeywordsProsystemin Volatile Plant–insect interaction Gene expression Indirect defense
We thank Clarence Ryan (Institute of Biological Chemistry, Washington State University) for providing the seeds and useful suggestions during manuscript preparation and Adele Cataldo for technical support. This work was supported by Ministero dell’Università e Ricerca Scientifica (PRIN 2004, MIUR Progetto n. 32 Regioni Obiettivo 1).
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