New insights into plant responses to the attack from insect herbivores.

Plants have evolved sophisticated systems to cope with herbivore challenges. When plants perceive herbivore-derived physical and chemical cues, such as elicitors in insects' oral secretions and compounds in oviposition fluids, plants dramatically reshape their transcriptomes, proteomes, and metabolomes. All these herbivory-induced changes are mediated by elaborate signaling networks, which include receptors/sensors, Ca(2+) influxes, kinase cascades, reactive oxygen species, and phytohormone signaling pathways. Furthermore, herbivory induces defense responses not only in the wounded regions but also in undamaged regions in the attacked leaves and in distal intact (systemic) leaves. Here, we review recent progress in understanding plant perception of herbivory and oviposition, and the herbivory-induced early signaling events and their biological functions. We consider the intraspecific phenotypic diversity of plant responses to herbivory and discuss the underlying genetic variation. We also discuss new tools and technical challenges in studying plant-herbivore interactions.