Virulence regulation in plant-pathogenic bacteria by host-secreted signals

Abstract

Bacterial pathogens manipulate host signaling pathways and evade host defenses using effector molecules, coordinating their deployment to ensure successful infection. However, host-derived metabolites as signals, and their critical role in regulating bacterial virulence requires further insights. Effective regulation of virulence, which is essential for pathogenic bacteria, involves controlling factors that enable colonization, defense evasion, and tissue damage. This regulation is dynamic, influenced by environmental cues including signals from host plants like exudates. Plant exudates, comprising of diverse compounds released by roots and tissues, serve as rich chemical signals affecting the behavior and virulence of associated bacteria. Plant nutrients act as signaling molecules that are sensed through membrane-localized receptors and intracellular response mechanisms in bacteria. This review explains how different bacteria detect and answer to secreted chemical signals, regulating virulence gene expression. Our main emphasis is exploring the recognition process of host-originated signaling molecules through molecular sensors on cellular membranes and intracellular signaling pathways. This review encompasses insights into how bacterial strains individually coordinate their virulence in response to various distinct host-derived signals that can positively or negatively regulate their virulence. Furthermore, we explained the interruption of plant defense with the perception of host metabolites to dampen pathogen virulence. The intricate interplay between pathogens and plant signals, particularly in how pathogens recognize host metabolic signals to regulate virulence genes, portrays a crucial initial interaction leading to profound influences on infection outcomes. This work will greatly aid researchers in developing new strategies for preventing and treating infections.