Genetics and diversity of rhizobia-legume symbioses

Molecular Plant-Microbe Interactions, Microbiology

Inside specialized cells of leguminous plants, soil bacteria known collectively as rhizobia convert chemically inert atmospheric nitrogen into a reduced form that sustains plant growth. Efficient nitrogen fixation occurs predominantly inside root nodules, in which rhizobia require establishing persistent intracellular infections. As symbiotic nitrogen fixation occurs only when plants encounter compatible rhizobia, we search to identify the molecular determinants that make the unusually promiscuous Sinorhizobium fredii strain NGR234 capable of forming proficient associations with >135 legume species.

Applied to cultivated crops, rhizobial inoculants contribute to preserve water resources from pollution by excess fertilizers, reduce agriculture’s carbon footprint, and improve soil quality. That commercial inoculants are rapidly outcompeted by indigenous strains, illustrates our still limited understanding of microbe population dynamics along a growing root. To better assess the dynamics of nodulation in fields and diversity of rhizobia-legume solutions that exist in nature, we have established time-of-flight mass spectrometry as a new tool to rapidly and reliably characterize symbiotic strains in situ.


Recent Publications

  • A Minimal Genetic Passkey to Unlock Many Legume Doors to Root Nodulation by Rhizobia
    Unay, Jovelyn; Perret, Xavier
    Genes 10.3390/genes11050521 MAY 2020
  • Bradyrhizobium ivorense sp. nov. as a potential local bioinoculant for Cajanus cajan cultures in Cote d'Ivoire
    Fossou, Romain K.; Pothier, Joel F.; Zeze, Adolphe; Perret, Xavier
    International Journal Of Systematic And Evolutionary Microbiology  DOI: 10.1099/ijsem.0.003931 2020
  • Loss of NifQ Leads to Accumulation of Porphyrins and Altered Metal-Homeostasis in Nitrogen-Fixing Symbioses
    Saad, MM; Michalet, S; Fossou, R; Putnik-Delic, M; Crevecoeur, M; Meyer, J; de Malezieux, C; Hopfgartner, G; Maksimovic, I; Perret, X
    MOLECULAR PLANT-MICROBE INTERACTIONS, 32 (2):208-216; 10.1094/MPMI-07-18-0188-R FEB 2019
  • Deletion of rRNA Operons of Sinorhizobium fredii Strain NGR234 and Impact on Symbiosis With Legumes
    Cherni, Ala Eddine; Perret, Xavier
    FRONTIERS IN MICROBIOLOGY, 10 10.3389/fmicb.2019.00154 FEB 13 2019
  • Sinorhizobium fredii Strains HH103 and NGR234 Form Nitrogen Fixing Nodules With Diverse Wild Soybeans (Glycine sofa) From Central China but Are Ineffective on Northern China Accessions
    Temprano-Vera, F; Rodriguez-Navarro, DN; Acosta-Jurado, S; Perret, X; Fossou, RK; Navarro-Gomez, P; Zhen, T; Yu, DS; An, Q; Buendia-Claveria, AM; Moreno, J; Lopez-Baena, FJ; Ruiz-Sainz, JE; Vinardell, JM
    FRONTIERS IN MICROBIOLOGY, 9 10.3389/fmicb.2018.02843 NOV 21 2018
  • Two Major Clades of Bradyrhizobia Dominate Symbiotic Interactions with Pigeonpea in Fields of Cote d'Ivoire 
    Fossou, Romain K.; Ziegler, Dominik; Zeze, Adolphe; et al. 
    FRONTIERS IN MICROBIOLOGY, 7: 10.3389/fmicb.2016.01793 NOV 11 2016
  • Metaproteomics and ultrastructure characterization of Komagataeibacter spp. involved in high-acid spirit vinegar production 
    Andres-Barrao, Cristina; Saad, Maged M.; Ferrete, Elena Cabello; et al. 
    FOOD MICROBIOLOGY, 55: 112-122, 10.1016/ MAY 2016 Article
  • Ribosomal protein biomarkers provide root nodule bacterial identification by MALDI-TOF MS 
    Ziegler, Dominik; Pothier, Joel F.; Ardley, Julie; et al. 
    APPLIED MICROBIOLOGY AND BIOTECHNOLOGY, 99 (13): 5547-5562, 10.1007/s00253-015-6515-3  JUL 2015
  • CO2 assimilation in the chemocline of Lake Cadagno is dominated by a few types of phototrophic purple sulfur bacteria 
    Storelli, Nicola; Peduzzi, Sandro; Saad, Maged M.; et al. 
    FEMS MICROBIOLOGY ECOLOGY, 84 (2): 421-432, 10.1111/1574-6941.12074 MAY 2013
Xavier Perret

Dr. Xavier Perret
University of Geneva
Department of Botany and Plant Biology
1211 Geneva

Tel: +41 (0)22 379 31 17

Research topics

  • genetics of nodulation
  • genetics of nitrogen fixation
  • gene regulation in rhizobia
  • rhizobial diversity in soil



  • plant-microbe interactions
  • plant responses to microbial infections
  • plant-bacteria signalling
  • soil biodiversity