Insect Eggs Can Enhance Wound Response in Plants: A Study System of Tomato <em>Solanum lycopersicum</em> L. and <em>Helicoverpa zea</em> Boddie

<div><p>Insect oviposition on plants frequently precedes herbivory. Accumulating evidence indicates that plants recognize insect oviposition and elicit direct or indirect defenses to reduce the pressure of future herbivory. Most of the oviposition-triggered plant defenses described thus far remove eggs or keep them away from the host plant or their desirable feeding sites. Here, we report induction of antiherbivore defense by insect oviposition which targets newly hatched larvae, not the eggs, in the system of tomato <em>Solanum lycopersicum</em> L., and tomato fruitworm moth <em>Helicoverpa zea</em> Boddie. When tomato plants were oviposited by <em>H. zea</em> moths, <em>pin2</em>, a highly inducible gene encoding protease inhibitor2, which is a representative defense protein against herbivorous arthropods, was expressed at significantly higher level at the oviposition site than surrounding tissues, and expression decreased with distance away from the site of oviposition. Moreover, more eggs resulted in higher <em>pin2</em> expression in leaves, and both fertilized and unfertilized eggs induced <em>pin2</em> expression. Notably, when quantified daily following deposition of eggs, <em>pin2</em> expression at the oviposition site was highest just before the emergence of larvae. Furthermore, <em>H. zea</em> oviposition primed the wound-induced increase of <em>pin2</em> transcription and a burst of jasmonic acid (JA); tomato plants previously exposed to <em>H. zea</em> oviposition showed significantly stronger induction of <em>pin2</em> and higher production of JA upon subsequent simulated herbivory than without oviposition. Our results suggest that tomato plants recognize <em>H. zea</em> oviposition as a signal of impending future herbivory and induce defenses to prepare for this herbivory by newly hatched neonate larvae.</p>