Molecular and Genomic Characterization of the Pseudomonas syringae Phylogroup 4: An Emerging Pathogen of Arabidopsis thaliana and Nicotiana benthamiana

Abstract

Environmental fluctuations such as increased temperature, water availability, and air CO2 concentration triggered by 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 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.

Unraveling the genetic architecture of the adaptive potential of Arabidopsis thaliana to face the bacterial pathogen Pseudomonas syringae in the context of global change

“…On the other hand, the high virulence of the RAYR-B strain on diverse sets of A. thaliana accessions is likely mediated by the T3E HopBJ1, previously identified and functionally characterized in this strain as inducing ROS accumulation and cell death both in Arabidopsis and in tobacco (Fuenzalida-Valdivia et al, 2022;Zavala et al, 2022). Importantly, no genetic variation was detected between the seven TOU-A accessions in response to the three P. viridiflava strains NAUV-BL, RADE-AL and SAUB-BL, which can induce severe symptoms (Figure 2, Table S2).…”

“…On the other hand, the high virulence of the RAYR-B strain on diverse sets of A. thaliana accessions is likely mediated by the T3E HopBJ1, previously identified and functionally characterized in this strain as inducing ROS accumulation and cell death both in Arabidopsis and in tobacco (Fuenzalida-Valdivia et al, 2022; Zavala et al, 2022).…”

The genetic architecture of the adaptive potential of Arabidopsis thaliana in response to Pseudomonas syringae strains isolated from south‐west France

“…On the other hand, the high virulence of the RAYR-B strain on diverse sets of A. thaliana accessions is probably mediated by the T3E HopBJ1, previously identified and functionally characterized in this strain as inducing reactive oxygen species accumulation and cell death both in Arabidopsis and in tobacco (Zavala et al, 2022).…”

Comparative genomic analyses provide insight into the pathogenicity of three Pseudomonas syringae pv. actinidiae strains from Anhui Province, China

“…With decreased sequencing costs and rapid development of sequencing techniques, the genomes of diverse bacterial strains have been sequenced. Complete or draft genome analyses have been performed for important phytopathogenic P. syringae [ 15 , 16 ]. The sequencing of multiple strains within a species or pathovar can provide crucial insights into potential evolutionary differences.…”