Research focusses

In a world context of overconsumption of nitrogen fertilizers leading to environmental damages, the study of nitrogen-fixing symbioses is a major issue. Nitrogen is a key element in plants, and in spite of huge amounts of nitrogen in the atmosphere (78% of dinitrogen), its availability is one of the major limiting factor for plant growth. Only so-called « nitrogen-fixing » bacteria are capable of reducing dinitrogen into ammonia.

Our research project focusses on Casuarina glauca, a tropical tree growing in semi-arid and arid areas, that has the ability to develop nitrogen fixing nodules (also referred as « actinorhiza ») following a symbiotic interaction with the soil actinobacteria Frankia. Studies aim to decipher the molecular mechanisms underlying the actinorhizal symbiosis, with a major focus on the early stages of the dialogue between the host plant and the microorganism. Our work on Casuarina-Frankia also relies on knowledge of two other root endosymbioses, the Rhizobium-legume symbiosis and the endomycorrhizal symbiosis. The comparative analysis of these beneficial plant-microbe interactions will contribute to understand how some plants from the Rosid I clade acquired the ability to develop nitrogen fixing nodules about 70 million years ago. The long-term challenge of these studies is to transfer the ability to fix nitrogen to cereals such as rice, maize and wheat.

C glauca x

Casuarina glauca



  • Symbiotic signalling by Frankia (ANR SYMACTINO)
  • Functional charaterization of symbiotic genes from Casuarina glauca involved in the interaction with Frankia (ANR SESAM)
  • Contribution of the actinorhizal symbiosis to salt tolerance (IMHOTEP project)
  • Gene transfer procedures for valuable Casuarinaceae trees (Chinese Academy of Forestry)
  • Transfer of nitrogen-fixing ability to non-legumes (SYMBIFIX network)
  • Impact of agropolymers on symbiotic interactions (Rhodia-Labex Agro project)


Team Members

  • Claudine FRANCHE, Senior Researcher, group leader, IRD
  • Didier BOGUSZ, Senior Researcher, group leader, IRD
  • Jocelyne Bonneau, Technician, IRD


  • Emilie FROUSSART, PhD thesis 2014-2017 (IRD-University Montpellier-Solvay)


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Other partners


  • University Lyon 1; Laboratory of Plant-Microbe Interactions
  • Rhodia-Solvay.


  • University Constantine 1, Algeria
  • University Cheikh Anta Diop, Senegal
  • University Mohammed V Agdal, Morocco
  • Suez Canal University, Egypt.