The Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root Nodules
The nitrogen-fixing bacterium Sinorhizobium meliloti must adapt to diverse conditions encountered during its symbiosis with leguminous plants. We characterized a new symbiotically relevant gene, emrR (SMc03169), whose product belongs to the TetR family of repressors and is divergently transcribed fr...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
The American Phytopathological Society
2014-04-01
|
| Series: | Molecular Plant-Microbe Interactions |
| Online Access: | https://apsjournals.apsnet.org/doi/10.1094/MPMI-09-13-0284-R |
| _version_ | 1811290230166126592 |
|---|---|
| author | Mário R. Santos Andreia T. Marques Jörg D. Becker Leonilde M. Moreira |
| author_facet | Mário R. Santos Andreia T. Marques Jörg D. Becker Leonilde M. Moreira |
| author_sort | Mário R. Santos |
| collection | DOAJ |
| description | The nitrogen-fixing bacterium Sinorhizobium meliloti must adapt to diverse conditions encountered during its symbiosis with leguminous plants. We characterized a new symbiotically relevant gene, emrR (SMc03169), whose product belongs to the TetR family of repressors and is divergently transcribed from emrAB genes encoding a putative major facilitator superfamily–type efflux pump. An emrR deletion mutant produced more succinoglycan, displayed increased cell-wall permeability, and exhibited higher tolerance to heat shock. It also showed lower tolerance to acidic conditions, a reduced production of siderophores, and lower motility and biofilm formation. The simultaneous deletion of emrA and emrR genes restored the mentioned traits to the wild-type phenotype, except for survival under heat shock, which was lower than that displayed by the wild-type strain. Furthermore, the ΔemrR mutant as well as the double ΔemrAR mutant was impaired in symbiosis with Medicago sativa; it formed fewer nodules and competed poorly with the wild-type strain for nodule colonization. Expression profiling of the ΔemrR mutant showed decreased expression of genes involved in Nod-factor and rhizobactin biosynthesis and in stress responses. Expression of genes directing the biosynthesis of succinoglycan and other polysaccharides were increased. EmrR may therefore be involved in a regulatory network targeting membrane and cell wall modifications in preparation for colonization of root hairs during symbiosis. |
| first_indexed | 2024-04-13T04:09:14Z |
| format | Article |
| id | doaj.art-bfb2a8f670a54cf18cd67b081615354c |
| institution | Directory Open Access Journal |
| issn | 0894-0282 1943-7706 |
| language | English |
| last_indexed | 2024-04-13T04:09:14Z |
| publishDate | 2014-04-01 |
| publisher | The American Phytopathological Society |
| record_format | Article |
| series | Molecular Plant-Microbe Interactions |
| spelling | doaj.art-bfb2a8f670a54cf18cd67b081615354c2022-12-22T03:03:10ZengThe American Phytopathological SocietyMolecular Plant-Microbe Interactions0894-02821943-77062014-04-0127438839910.1094/MPMI-09-13-0284-RThe Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root NodulesMário R. SantosAndreia T. MarquesJörg D. BeckerLeonilde M. MoreiraThe nitrogen-fixing bacterium Sinorhizobium meliloti must adapt to diverse conditions encountered during its symbiosis with leguminous plants. We characterized a new symbiotically relevant gene, emrR (SMc03169), whose product belongs to the TetR family of repressors and is divergently transcribed from emrAB genes encoding a putative major facilitator superfamily–type efflux pump. An emrR deletion mutant produced more succinoglycan, displayed increased cell-wall permeability, and exhibited higher tolerance to heat shock. It also showed lower tolerance to acidic conditions, a reduced production of siderophores, and lower motility and biofilm formation. The simultaneous deletion of emrA and emrR genes restored the mentioned traits to the wild-type phenotype, except for survival under heat shock, which was lower than that displayed by the wild-type strain. Furthermore, the ΔemrR mutant as well as the double ΔemrAR mutant was impaired in symbiosis with Medicago sativa; it formed fewer nodules and competed poorly with the wild-type strain for nodule colonization. Expression profiling of the ΔemrR mutant showed decreased expression of genes involved in Nod-factor and rhizobactin biosynthesis and in stress responses. Expression of genes directing the biosynthesis of succinoglycan and other polysaccharides were increased. EmrR may therefore be involved in a regulatory network targeting membrane and cell wall modifications in preparation for colonization of root hairs during symbiosis.https://apsjournals.apsnet.org/doi/10.1094/MPMI-09-13-0284-R |
| spellingShingle | Mário R. Santos Andreia T. Marques Jörg D. Becker Leonilde M. Moreira The Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root Nodules Molecular Plant-Microbe Interactions |
| title | The Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root Nodules |
| title_full | The Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root Nodules |
| title_fullStr | The Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root Nodules |
| title_full_unstemmed | The Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root Nodules |
| title_short | The Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root Nodules |
| title_sort | sinorhizobium meliloti emrr regulator is required for efficient colonization of medicago sativa root nodules |
| url | https://apsjournals.apsnet.org/doi/10.1094/MPMI-09-13-0284-R |
| work_keys_str_mv | AT mariorsantos thesinorhizobiummelilotiemrrregulatorisrequiredforefficientcolonizationofmedicagosativarootnodules AT andreiatmarques thesinorhizobiummelilotiemrrregulatorisrequiredforefficientcolonizationofmedicagosativarootnodules AT jorgdbecker thesinorhizobiummelilotiemrrregulatorisrequiredforefficientcolonizationofmedicagosativarootnodules AT leonildemmoreira thesinorhizobiummelilotiemrrregulatorisrequiredforefficientcolonizationofmedicagosativarootnodules AT mariorsantos sinorhizobiummelilotiemrrregulatorisrequiredforefficientcolonizationofmedicagosativarootnodules AT andreiatmarques sinorhizobiummelilotiemrrregulatorisrequiredforefficientcolonizationofmedicagosativarootnodules AT jorgdbecker sinorhizobiummelilotiemrrregulatorisrequiredforefficientcolonizationofmedicagosativarootnodules AT leonildemmoreira sinorhizobiummelilotiemrrregulatorisrequiredforefficientcolonizationofmedicagosativarootnodules |