Induced disease resistance signaling in plants

Abstract

To protect themselves from disease, plants have evolved sophisticated inducible defense mechanisms in which the signal molecules salicylic acid, jasmonic acid and ethylene often play crucial roles. Elucidation of signaling pathways controlling induced disease resistance is a major objective in research on plant-pathogen interactions. The capacity of a plant to develop a broad-spectrum, systemic acquired resistance (SAR) after primary infection with a necrotizing pathogen is well known and its signal transduction pathway extensively studied. Plants of which the roots have been colonized by specific strains of non-pathogenic fluorescent Pseudomonas spp. develop a phenotypically similar form of protection that is called rhizobacteria-mediated induced systemic resistance (ISR). In contrast to pathogen-induced SAR, which is regulated by salicylic acid, rhizobacteria-mediated ISR is controlled by a signaling pathway in which the phytohormones jasmonic acid and ethylene play key roles. In the past decade, the model plant species Arabidopsis thaliana has been extensively explored to study the molecular basis of systemically induced resistance. Here we review the current knowledge on induced disease resistance signaling in plants.