Abstract
The interaction between Arabidopsis thaliana and the hemibiotrophic pathogen Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) is a good model for understanding the dynamics of plant-pathogen interactions. We employed a multifaceted approach utilizing microarray based transcriptome analysis validated by real-time PCR, coupled with physiological changes, histochemical staining, and the SEM analysis, to investigate the molecular, biochemical, and physiological processes governing the host-pathogen interaction and its outcome. Transcriptomic analysis revealed upregulation of defense genes, including key transcription factors (WRKY, ERF, NAC, bZIP), salicylic acid-responsive genes (PR1, NPR1), and MAPK signaling proteins, contrasted by the downregulation of genes specific to photosynthesis and auxin signaling. Physiological analyses confirmed an oxidative burst, evidenced by an elevated ROS and NO (validated via DAB and NBT staining), and accompanied by a decrease in stomatal conductance. SEM analysis confirmed significant morphological and structural changes, including disrupted trichomes and compromised silique development. Functional annotation highlighted a biphasic defense mechanism, characterized by an initial SA-mediated response transitioning to JA signaling. The observed modified auxin signaling likely enhances pathogen virulence by undermining host defenses. This study provides in-depth insight into these molecular interactions, demonstrating how Pst DC3000 exploits host defense pathways, thereby identifying potential targets for agricultural strategies to enhance bacterial resistance. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-025-01688-x.