Environmental fluctuations such as increased temperature, water availability, and air CO2 concentration triggered by Racks / Carriers climate change influence plant disease dynamics by affecting hosts, pathogens, and their interactions.Here, we describe a newly discovered Pseudomonas syringae strain found in a natural population of Arabidopsis thaliana collected from the southwest of France.This strain, called Psy RAYR-BL, is highly virulent on natural Arabidopsis accessions, Arabidopsis model accession Columbia 0, and tobacco plants.Despite the severe disease phenotype caused by the Psy RAYR-BL strain, we identified a reduced repertoire of putative Type III virulence effectors by genomic sequencing compared to P.syringae pv tomato (Pst) DC3000.
Furthermore, hopBJ1Psy is found exclusively on the Psy RAYR-BL genome but not in the Pst DC3000 genome.The plant expression of HopBJ1Psy induces ROS accumulation and cell death.In addition, HopBJ1Psy participates as a virulence Wallet factor in this plant-pathogen interaction, likely explaining the severity of the disease symptoms.This research describes the characterization of a newly discovered plant pathogen strain and possible virulence mechanisms underlying the infection process shaped by natural and changing environmental conditions.