Negative Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicola
Many plant-pathogenic bacteria require type III secretion systems (T3SS) to cause disease in compatible hosts and to induce the hypersensitive response in resistant plants. T3SS gene expression is induced within the plant and responds to host and environmental factors. In Pseudomonas syringae, expre...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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The American Phytopathological Society
2010-05-01
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| Series: | Molecular Plant-Microbe Interactions |
| Online Access: | https://apsjournals.apsnet.org/doi/10.1094/MPMI-23-5-0682 |
| _version_ | 1819081458675875840 |
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| author | Inmaculada Ortiz-Martín Richard Thwaites John W. Mansfield Carmen R. Beuzón |
| author_facet | Inmaculada Ortiz-Martín Richard Thwaites John W. Mansfield Carmen R. Beuzón |
| author_sort | Inmaculada Ortiz-Martín |
| collection | DOAJ |
| description | Many plant-pathogenic bacteria require type III secretion systems (T3SS) to cause disease in compatible hosts and to induce the hypersensitive response in resistant plants. T3SS gene expression is induced within the plant and responds to host and environmental factors. In Pseudomonas syringae, expression is downregulated by the Lon protease in rich medium and by HrpV under inducing conditions. HrpV acts as an anti-activator by binding HrpS. HrpG, which can also bind HrpV, has been reported to act as an anti-anti-activator. Previous studies have used mostly in vitro inducing conditions, different pathovars, and methodology. We have used single and double lon and hrpV mutants of P. syringae pv. phaseolicola 1448a, as well as strains ectopically expressing the regulators, to examine their role in coordinating expression of the T3SS. We applied real-time polymerase chain reaction to analyze gene expression both in vitro and in planta, and assessed bacterial fitness using competitive indices. Our results indicate that i) Lon downregulates expression of the hrp/hrc genes in all conditions, probably by constitutively degrading naturally unstable HrpR; ii) HrpV and HrpT downregulate expression of the hrp/hrc genes in all conditions; and iii) HrpG has an additional, HrpV-independent role, regulating expression of the hrpC operon. |
| first_indexed | 2024-12-21T20:01:06Z |
| format | Article |
| id | doaj.art-2580918092264cd48b5b661be3d7260a |
| institution | Directory Open Access Journal |
| issn | 0894-0282 1943-7706 |
| language | English |
| last_indexed | 2024-12-21T20:01:06Z |
| publishDate | 2010-05-01 |
| publisher | The American Phytopathological Society |
| record_format | Article |
| series | Molecular Plant-Microbe Interactions |
| spelling | doaj.art-2580918092264cd48b5b661be3d7260a2022-12-21T18:51:58ZengThe American Phytopathological SocietyMolecular Plant-Microbe Interactions0894-02821943-77062010-05-0123568270110.1094/MPMI-23-5-0682Negative Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicolaInmaculada Ortiz-MartínRichard ThwaitesJohn W. MansfieldCarmen R. BeuzónMany plant-pathogenic bacteria require type III secretion systems (T3SS) to cause disease in compatible hosts and to induce the hypersensitive response in resistant plants. T3SS gene expression is induced within the plant and responds to host and environmental factors. In Pseudomonas syringae, expression is downregulated by the Lon protease in rich medium and by HrpV under inducing conditions. HrpV acts as an anti-activator by binding HrpS. HrpG, which can also bind HrpV, has been reported to act as an anti-anti-activator. Previous studies have used mostly in vitro inducing conditions, different pathovars, and methodology. We have used single and double lon and hrpV mutants of P. syringae pv. phaseolicola 1448a, as well as strains ectopically expressing the regulators, to examine their role in coordinating expression of the T3SS. We applied real-time polymerase chain reaction to analyze gene expression both in vitro and in planta, and assessed bacterial fitness using competitive indices. Our results indicate that i) Lon downregulates expression of the hrp/hrc genes in all conditions, probably by constitutively degrading naturally unstable HrpR; ii) HrpV and HrpT downregulate expression of the hrp/hrc genes in all conditions; and iii) HrpG has an additional, HrpV-independent role, regulating expression of the hrpC operon.https://apsjournals.apsnet.org/doi/10.1094/MPMI-23-5-0682 |
| spellingShingle | Inmaculada Ortiz-Martín Richard Thwaites John W. Mansfield Carmen R. Beuzón Negative Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicola Molecular Plant-Microbe Interactions |
| title | Negative Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicola |
| title_full | Negative Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicola |
| title_fullStr | Negative Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicola |
| title_full_unstemmed | Negative Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicola |
| title_short | Negative Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicola |
| title_sort | negative regulation of the hrp type iii secretion system in pseudomonas syringae pv phaseolicola |
| url | https://apsjournals.apsnet.org/doi/10.1094/MPMI-23-5-0682 |
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