Contribution of two-component response regulator OmpR to virulence, motility, exopolysaccharide production, and osmotic stress in Pseudomonas syringae pv. actinidiae
Abstract Bacterial canker disease caused by Pseudomonas syringae pv. actinidiae (Psa) is the most devastating disease in kiwifruit cultivation. The EnvZ/OmpR two-component system (TCS) has been confirmed to regulate virulence and mediate environmental stress responses in Gram-negative bacteria. Howe...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
BMC
2025-08-01
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| Series: | Phytopathology Research |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s42483-025-00353-1 |
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| Summary: | Abstract Bacterial canker disease caused by Pseudomonas syringae pv. actinidiae (Psa) is the most devastating disease in kiwifruit cultivation. The EnvZ/OmpR two-component system (TCS) has been confirmed to regulate virulence and mediate environmental stress responses in Gram-negative bacteria. However, the functional role of EnvZ/OmpR in Psa has not been fully clarified. In this study, we constructed markerless ompR, envZ, and ompR-envZ mutants, and ompR complementation and overexpression strains using homologous recombination. The deletion of ompR or envZ tremendously reduced the swimming and swarming motility of Psa, as well as tolerance to osmotic stress, while overexpression of ompR impaired its virulence against kiwifruit but enhanced exopolysaccharide production. EnvZ negatively regulated hrpR/S expression in both King’s B and minimal medium, whereas OmpR regulated hrpR/S expression negatively in King’s B and positively in minimal medium. However, OmpR did not regulate the expression of genes gacA, algU, lpxC, fur, and fleQ, which are associated with known virulence functions, despite its binding to their promoters. Additionally, based on bioinformatic prediction, two new OmpR regulons (envC and tolQ) related to virulence were identified in Psa. Meanwhile, OmpR directly bound to the promoters of envC and tolQ, and negatively regulated their expression in minimal medium. These findings enrich our understanding of the OmpR-mediated regulatory network and its roles in the pathogenesis of P. syringae. |
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| ISSN: | 2524-4167 |