Transcriptome Analysis Reveals Key Players in Plant Immunity Triggered by Diffusible Signal Factor (DSF), a <i>Xanthomonas</i> -Secreted Quorum-Sensing Molecule

Plants are constantly exposed to diverse pathogens and have evolved sophisticated defense mechanisms to detect and respond to microbial threats. Pathogen recognition is often mediated by pathogen-associated molecular patterns (PAMPs), such as cell wall components or secreted molecules. Quorum-sensing molecules, secreted by bacteria to regulate virulence factors, are an emerging class of PAMPs that plants can detect as signs of infection. One such molecule, diffusible signal factor (DSF), is secreted by <i>Xanthomonas</i> plant pathogens. Previous studies have shown that DSF induces immune responses in plants such as Arabidopsis and rice. However, the plant mechanisms involved in DSF perception and immune response remain poorly understood. In this study, we performed transcriptome analysis to investigate the molecular players involved in DSF-induced immunity in Arabidopsis. Our findings identified key molecules, including WRKY66, PEPR2, and WAK_PK, as players in DSF-mediated immune responses. However, none of these molecules appears to directly recognize DSF, as mutants still activate DSF-induced MAP kinase signaling. This suggests that additional unidentified receptors or signaling pathways may play a role in DSF perception. Our study elaborates the downstream events of DSF recognition as a PAMP and contributes to the growing body of knowledge on plant immune signaling. [Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.