Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of Rhizobia
Root-nodule development in legumes is an inducible developmental process initially triggered by perception of lipochitin-oligosaccharide signals secreted by the bacterial microsymbiont. In nature, rhizobial colonization and invasion of the legume root is therefore a prerequisite for formation of nit...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
The American Phytopathological Society
2006-04-01
|
| Series: | Molecular Plant-Microbe Interactions |
| Online Access: | https://apsjournals.apsnet.org/doi/10.1094/MPMI-19-0373 |
| _version_ | 1818757333719711744 |
|---|---|
| author | Leïla Tirichine Euan K. James Niels Sandal Jens Stougaard |
| author_facet | Leïla Tirichine Euan K. James Niels Sandal Jens Stougaard |
| author_sort | Leïla Tirichine |
| collection | DOAJ |
| description | Root-nodule development in legumes is an inducible developmental process initially triggered by perception of lipochitin-oligosaccharide signals secreted by the bacterial microsymbiont. In nature, rhizobial colonization and invasion of the legume root is therefore a prerequisite for formation of nitrogen-fixing root nodules. Here, we report isolation and characterization of chemically induced spontaneously nodulating mutants in a model legume amenable to molecular genetics. Six mutant lines of Lotus japonicus were identified in a screen for spontaneous nodule development under axenic conditions, i.e., in the absence of rhizobia. Spontaneous nodules do not contain rhizobia, bacteroids, or infection threads. Phenotypically, they resemble ineffective white nodules formed by some bacterial mutants on wild-type plants or certain plant mutants inoculated with wild-type Mesorhizobium loti. Spontaneous nodules formed on mutant lines show the ontogeny and characteristic histological features described for rhizobia-induced nodules on wild-type plants. Physiological responses to nitrate and ethylene are also maintained, as elevated levels inhibit spontaneous nodulation. Activation of the nodule developmental program in spontaneous nodules was shown for the early nodulin genes Enod2 and Nin, which are both upregulated in spontaneous nodules as well as in rhizobial nodules. Both monogenic recessive and dominant spontaneous nodule formation (snf) mutations were isolated in this mutant screen, and map positions were determined for three loci. We suggest that future molecular characterization of these mutants will identify key plant determinants involved in regulating nodulation and provide new insight into plant organ development. |
| first_indexed | 2024-12-18T06:09:16Z |
| format | Article |
| id | doaj.art-53b241c76e1d477baa3cb7b67c35deb3 |
| institution | Directory Open Access Journal |
| issn | 0894-0282 1943-7706 |
| language | English |
| last_indexed | 2024-12-18T06:09:16Z |
| publishDate | 2006-04-01 |
| publisher | The American Phytopathological Society |
| record_format | Article |
| series | Molecular Plant-Microbe Interactions |
| spelling | doaj.art-53b241c76e1d477baa3cb7b67c35deb32022-12-21T21:18:27ZengThe American Phytopathological SocietyMolecular Plant-Microbe Interactions0894-02821943-77062006-04-0119437338210.1094/MPMI-19-0373Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of RhizobiaLeïla TirichineEuan K. JamesNiels SandalJens StougaardRoot-nodule development in legumes is an inducible developmental process initially triggered by perception of lipochitin-oligosaccharide signals secreted by the bacterial microsymbiont. In nature, rhizobial colonization and invasion of the legume root is therefore a prerequisite for formation of nitrogen-fixing root nodules. Here, we report isolation and characterization of chemically induced spontaneously nodulating mutants in a model legume amenable to molecular genetics. Six mutant lines of Lotus japonicus were identified in a screen for spontaneous nodule development under axenic conditions, i.e., in the absence of rhizobia. Spontaneous nodules do not contain rhizobia, bacteroids, or infection threads. Phenotypically, they resemble ineffective white nodules formed by some bacterial mutants on wild-type plants or certain plant mutants inoculated with wild-type Mesorhizobium loti. Spontaneous nodules formed on mutant lines show the ontogeny and characteristic histological features described for rhizobia-induced nodules on wild-type plants. Physiological responses to nitrate and ethylene are also maintained, as elevated levels inhibit spontaneous nodulation. Activation of the nodule developmental program in spontaneous nodules was shown for the early nodulin genes Enod2 and Nin, which are both upregulated in spontaneous nodules as well as in rhizobial nodules. Both monogenic recessive and dominant spontaneous nodule formation (snf) mutations were isolated in this mutant screen, and map positions were determined for three loci. We suggest that future molecular characterization of these mutants will identify key plant determinants involved in regulating nodulation and provide new insight into plant organ development.https://apsjournals.apsnet.org/doi/10.1094/MPMI-19-0373 |
| spellingShingle | Leïla Tirichine Euan K. James Niels Sandal Jens Stougaard Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of Rhizobia Molecular Plant-Microbe Interactions |
| title | Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of Rhizobia |
| title_full | Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of Rhizobia |
| title_fullStr | Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of Rhizobia |
| title_full_unstemmed | Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of Rhizobia |
| title_short | Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of Rhizobia |
| title_sort | spontaneous root nodule formation in the model legume lotus japonicus a novel class of mutants nodulates in the absence of rhizobia |
| url | https://apsjournals.apsnet.org/doi/10.1094/MPMI-19-0373 |
| work_keys_str_mv | AT leilatirichine spontaneousrootnoduleformationinthemodellegumelotusjaponicusanovelclassofmutantsnodulatesintheabsenceofrhizobia AT euankjames spontaneousrootnoduleformationinthemodellegumelotusjaponicusanovelclassofmutantsnodulatesintheabsenceofrhizobia AT nielssandal spontaneousrootnoduleformationinthemodellegumelotusjaponicusanovelclassofmutantsnodulatesintheabsenceofrhizobia AT jensstougaard spontaneousrootnoduleformationinthemodellegumelotusjaponicusanovelclassofmutantsnodulatesintheabsenceofrhizobia |