Regulatory role of phytohormones in the interaction of plants with insect herbivores

Abstract

Insect herbivores affect crop growth worldwide, causing significant yield losses annually. Phytohormones are prime signaling molecules that coordinate many physiological phenomena, besides triggering stress-responsive regulatory genes involved in plant defense. Here, we present a holistic picture of the central role of various phytohormones—jasmonic acid, salicylic acid, ethylene, abscisic acid, auxin, cytokinin, gibberellins, and brassinosteroids in regulating the diverse molecular interactions between plants and insect herbivores. With an initial overview of the early signaling response, the chapter majorly focuses on the role of different key phytohormones in defending plants against herbivory and their cross talk. We also describe the phytohormone-mediated production of secondary metabolites and other defense toxins to counteract harmful herbivores. With the well-established myriad of information in selected plant–herbivore model systems, it is now critical to translate this knowledge to less explored crop plants for sustainable development in agriculture.