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.

• 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/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

• 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