Bradyrhizobium BclA Is a Peptide Transporter Required for Bacterial Differentiation in Symbiosis with Aeschynomene Legumes

Mol Plant Microbe Interact. 2015 Nov;28(11):1155-66. doi: 10.1094/MPMI-04-15-0094-R. Epub 2015 Oct 2.


Nodules of legume plants are highly integrated symbiotic systems shaped by millions of years of evolution. They harbor nitrogen-fixing rhizobium bacteria called bacteroids. Several legume species produce peptides called nodule-specific cysteine-rich (NCR) peptides in the symbiotic nodule cells which house the bacteroids. NCR peptides are related to antimicrobial peptides of innate immunity. They induce the endosymbionts into a differentiated, enlarged, and polyploid state. The bacterial symbionts, on their side, evolved functions for the response to the NCR peptides. Here, we identified the bclA gene of Bradyrhizobium sp. strains ORS278 and ORS285, which is required for the formation of differentiated and functional bacteroids in the nodules of the NCR peptide-producing Aeschynomene legumes. The BclA ABC transporter promotes the import of NCR peptides and provides protection against the antimicrobial activity of these peptides. Moreover, BclA can complement the role of the related BacA transporter of Sinorhizobium meliloti, which has a similar symbiotic function in the interaction with Medicago legumes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Bradyrhizobium / genetics
  • Bradyrhizobium / metabolism*
  • Bradyrhizobium / physiology
  • Fabaceae / metabolism
  • Fabaceae / microbiology
  • Flow Cytometry
  • Genetic Complementation Test
  • Host-Pathogen Interactions
  • Medicago / metabolism
  • Medicago / microbiology
  • Membrane Transport Proteins / classification
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Microscopy, Confocal
  • Molecular Sequence Data
  • Mutation
  • Peptides / metabolism
  • Phylogeny
  • Polyploidy
  • Root Nodules, Plant / metabolism
  • Root Nodules, Plant / microbiology
  • Sinorhizobium meliloti / genetics
  • Sinorhizobium meliloti / metabolism
  • Sinorhizobium meliloti / physiology
  • Symbiosis*


  • Bacterial Proteins
  • Membrane Transport Proteins
  • Peptides
  • peptide permease

Associated data

  • GENBANK/KR905749
  • GENBANK/KR905750