Plants take advantage of environmental cues to anticipate and prepare for future attack, allowing them to prepare (or “prime”) themselves for a potential impending attack. Airborne volatiles have been shown to be important cues that can prime plants. In particular, plant-derived volatiles from plants experiencing herbivory or related damage serve as putatively reliable indicators of stress. While Priming has been shown to be a widespread phenomenon, the fitness costs associated with response to an herbivore-associated cue are relatively unknown. To address this, we exposed Capsicum annuum (Pepper) and Phaseolus lunatus (Lima bean) to a continuous exposure of the green leaf volatile cis-3-hexenyl acetate (z3HAC), a plant-derived volatile compound that is a reliable indicator of potential herbivory, in a randomized field trial. We measured growth and reproduction in both species.
Results/Conclusions
Relative to their respective controls, z3HAC-exposed Pepper were shorter and produced fewer flowers and fruits while z3HAC-exposed Lima bean had increased floral production, grew taller, and produced more leaves. z3HAC-exposed Lima bean plants had less chewing herbivore damage, but appeared more attractive to aphids, than controls. Overall biomass accumulation in Pepper was also lower in z3HAC-treated plants. Moreover, z3HAC-exposed Pepper plants produced fewer, smaller fruits than did controls. These results indicate species-specific fitness implications of exposure to a volatile signaling cue. This suggests that the ecological footprint of volatile-mediated priming depends on the identity of the plant receiving the putative cue, which also has important implications for applied management strategies utilizing plant volatiles.