Identification of an insect-produced olfactory cue that primes plant defenses

Authors: HELMS, ANJEL - Pennsylvania State University; MORAES, CONSUELO - Eth Zurich; TROGER, ARMIN - University Of Hamburg; Alborn, Hans; FRANCKE, WITTKO - University Of Hamburg; TOOKER, JOHN - Pennsylvania State University; MESCHER, MARK - Eth Zurich

Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2017
Publication Date: 8/24/2017
Citation: Helms, A.M., Moraes, C.M., Troger, A., Alborn, H.T., Francke, W., Tooker, J.F., Mescher, M.C. 2017. Identification of an insect-produced olfactory cue that primes plant defenses. Nature Communications. 8(1):337. doi:10.1038/s41467-017-00335-8.

Interpretive Summary: Plants ability to defend themselves against herbivore attack is of fundamental importance for agricultural Integrated Pest Management (a multipronged approach to controlling insect pests) programs. It is increasingly clear that a plant’s defensive systems can be put on alert (primed) by odors released by neighboring plants in response to damage. This potentially critical aspect of plants ability to prepare their defense against imminent herbivore attack is still not fully understood. It was recently documented that odors from an herbivore, the goldenrod gall fly (Eurosta solidaginis) triggered priming of anti-herbivore defenses in tall goldenrod plants (Solidago altissima). A scientist at USDA ARS CMAVE in an international collaboration, identified the specific odor mediating this interaction as E,S-conophthorin, the most abundant component of the fly emission. This first ever described insect-produced odor with the ability to prime plant defense will provide new insights into the perceptual capabilities underlying plant defense priming in response to odor cues, and may lead to important knowledge about plant-insect interactions and how to help control insect pests of agricultural commodities.

Technical Abstract: It is increasingly clear that plants can perceive and respond to olfactory cues. Yet, knowledge about the specificity and sensitivity of such perception remains limited. We previously documented priming of anti-herbivore defenses in tall goldenrod plants (Solidago altissima) by volatile emissions from a specialist herbivore, the goldenrod gall fly (Eurosta solidaginis). Here we explore the specific chemical cues mediating this interaction. We report that E,S-conophthorin, the most abundant component of the fly emission, elicits a priming response equivalent to that elicited by the overall blend. Furthermore, while the strength of the priming response was dose dependent, plants responded even to very low concentrations of E,S-conophthorin relative to typical fly emissions. Evaluation of other blend components yielded results consistent with the hypothesis that priming in this interaction is mediated by a single compound. These findings provide new insights into the perceptual capabilities underlying plant defense priming in response to olfactory cues.