https://orcid.org/0000-0002-1797-7518
Figures & data
Figure 1. Plant defense priming in response to herbivory. Primer stimuli are environmental cues (e.g. volatile organic compounds from damaged neighboring plants, direct herbivore damage, spectral and chemical information) that elicit plant endogenous signaling and so ready plants for faster and stronger responses when additional attacks by herbivores occur (trigger stimulus). Intensity of the priming stimulus and the plant’s inherit sensitivity determine how strongly the plant is responding to a stimulus, reaching from alterations in endogenous signaling that may not significantly affect metabolism to a direct induction of defense metabolism. If the endogenous signal intensity elicit by environmental stimuli ranges within a critical signal intensity, a subsequent trigger stimulus (e.g. direct damage by a herbivore) will result in a faster and stronger expression of the plant defense metabolism. The reliability of a priming stimulus as a predictor of subsequent fitness-affecting damage will affect endogenous signal intensity and retention and thus if the priming information is stored in short- (e.g. transient, transcript and phytohormone accumulation) or long-term memory (e.g. epigenetic alterations). Defense priming allows the integration of environmental information to optimize plant responses while minimizing the costs associated with unreliable (false) environmental information.
Figure 2. The predictive value of environmental information to the plant defending against herbivory. The reliability of environmental information lies in the intensity of the primer stimulus, the plant’s sensitivity to the primer stimulus, and the environmental noise obstructing information transfer. Plants should evolve stronger priming responses (endogenous signaling) to more reliable environmental cues (A), while reducing the threshold for direct induction of defense-related metabolic changes (B). The threshold is determined by the zone of critical endogenous signal intensity, within which a trigger stimulus will induce stronger and faster responses and above which resistance is directly induced.
