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‚Äôs 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

  • 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/j.fm.2015.10.012 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
  • The Type 3 Protein Secretion System of Cupriavidus taiwanensis Strain LMG19424 Compromises Symbiosis with Leucaena leucocephala 
    Saad, Maged M. Crevecoeur, Michele; Masson-Boivin, Catherine; et al. 
    APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 78 (20): 7476-7479, 10.1128/AEM.01691-12 OCT 2012
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

 

Interdisciplinary

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