Signal transduction in plant-insect interactions: From membrane potential variations to metabolomics

Abstract

Upon herbivore attack plants react with a cascade of signals. Early events are represented by ion flux unbalances that eventually lead to plasma transmembrane potential (Vm) variations. These events are triggered by mechanical wounding implicated by chewing/piercing herbivores along with the injection of oral secretions (OS) containing plant response effectors and elicitors. Vm depolarization has been found to be a common event when plants interact with different biotrophs, and to vary depending on type and feeding habit of the biotroph. Here we show recent advances of internal and external signal transduction in plant-insect interactions by analyzing the differential impact of mechanical and herbivore damage on plants. Vm variations, calcium signaling, and ROS production precede the late events represented by gene expression, proteomics, and metabolomics. Transcriptomics allows to decipher genomic expression following Vm variations and signaling upon herbivory; proteomics helps to understand the biological function of expressed genes, whereas metabolomics gives feedbacks on the combined action of gene expression and protein synthesis, by showing the complexity of plant responses through synthesis of direct and indirect plant defense molecules. The practical application of modern methods starting from signal transduction to metabolic responses to insect herbivory are discussed and documented.