Current opinions about herbivore-associated molecular patterns and plant intracellular signaling

Elicitor-associated compounds included in oral secretions of herbivorous arthropods, defined as herbivore-associated molecular patterns (HAMPs), induce defense responses in plants. Recognition of HAMPs by the host plants triggers the activation of downstream intracellular and intercellular signaling, resulting in the production of defensive secondary metabolites and volatile emissions to defend against herbivore attack. Thus far, several chemical classes of HAMPs, e.g., fatty acid-amino acid conjugates, peptides, enzymes, and oligosaccharides, have been characterized from not only plant-chewing arthropod herbivores but also plant-sucking arthropod herbivores. Here, we introduce the latest insights about HAMPs and the HAMPs-induced defense signaling network in host plants.