Multiple steps control immunity during the intracellular accommodation of rhizobia - Archive ouverte HAL Access content directly
Journal Articles Journal of Experimental Botany Year : 2015

Multiple steps control immunity during the intracellular accommodation of rhizobia

Fathi Berrabah
  • Function : Author
  • PersonId : 1000328
Pascal Ratet


Medicago truncatula belongs to the legume family and forms symbiotic associations with nitrogen fixing bacteria, the rhizobia. During these interactions, the plants develop root nodules in which bacteria invade the plant cells and fix nitrogen for the benefit of the plant. Despite massive infection, legume nodules do not develop visible defence reactions, suggesting a special immune status of these organs. Some factors influencing rhizobium maintenance within the plant cells have been previously identified, such as the M. truncatula NCR peptides whose toxic effects are reduced by the bacterial protein BacA. In addition, DNF2, SymCRK, and RSD are M. truncatula genes required to avoid rhizobial death within the symbiotic cells. DNF2 and SymCRK are essential to prevent defence-like reactions in nodules after bacteria internalization into the symbiotic cells. Herein, we used a combination of genetics, histology and molecular biology approaches to investigate the relationship between the factors preventing bacterial death in the nodule cells. We show that the RSD gene is also required to repress plant defences in nodules. Upon inoculation with the bacA mutant, defence responses are observed only in the dnf2 mutant and not in the symCRK and rsd mutants. In addition, our data suggest that lack of nitrogen fixation by the bacterial partner triggers bacterial death in nodule cells after bacteroid differentiation. Together our data indicate that, after internalization, at least four independent mechanisms prevent bacterial death in the plant cell. These mechanisms involve successively: DNF2, BacA, SymCRK/RSD and bacterial ability to fix nitrogen.
Fichier principal
Vignette du fichier
Berrabah 2015 J. of Experimental Botany_1.pdf (3.01 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

hal-02410342 , version 1 (27-05-2020)


Attribution - CC BY 4.0



Fathi Berrabah, Pascal Ratet, Benjamin Gourion. Multiple steps control immunity during the intracellular accommodation of rhizobia. Journal of Experimental Botany, 2015, 66 (7), pp.1977-1985. ⟨10.1093/jxb/eru545⟩. ⟨hal-02410342⟩
37 View
60 Download



Gmail Facebook Twitter LinkedIn More