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24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

Menu Logo Principal Plant pathology unit - INRA AVIGNON

Pathologie vegetale

Zone de texte éditable et éditée et rééditée


Research Director, Head of the MISTRAL research team



  • My research concerns bacterial ecology. My team seeks to understand how the adaptation of bacteria to their environment affects two seemingly conflicting impacts on the environment: their capacity to
    • cause disease, and in particular newly emerging diseases
    • play beneficial roles in major environmental phenomena.
  • The bacterium Pseudomonas syringae is the focus of our work. It is a recurring pathogen on a wide range of crops of major importance. The bacterium is also one of the most highly active, naturally occurring ice nucleators in the environment. Its ice nucleation activity - at temperatures warmer than most other ice nucleators - and its ability to ascend into clouds with air currents has solicited great interest in its possible role in the atmospheric processes that lead to rainfall.
Effect of microbes on land-atmosphere interactions

Bioprecipitation (Morris, C.E. et al., 2014)

click on the figure to enlarge

Plant pathogens can reside is many habitats outside of agriculture as well as within and can move between these different habitats.  They can also have traits that are useful for their adaptation to all these different habitats and that lead them to play roles in a range of environmental phenomenon. For the bacterium Pseudomonas syringae, we study the influence of environmental habitats on the emergence of plant disease. We also study the dissemination of P. syringae via the water cycle and its influence on atmospheric processes that affect rainfall and lightning.

  • One of the long term goals of our work is to anticipate encounters of pathogenic strains of P. syringae from environmental reservoirs with crops and to identify the conditions most favorable for emergence. To accomplish this goal we :
    • identify the natural environmental reservoirs of P. syringae,
    • determine the role of these reservoirs in bacterial evolution,
    • assess the probability of dissemination to cultivated plants,
    • identify climatic factors most favorable for disease.
  • The other long term goal of our work is to contribute to land management strategies and policies that balance the dual roles of microorganisms that are plant pathogens and that are beneficial for rainfall. To accomplish this goal we :
    • identify sources of ice nucleation active microorganisms that are also plant pathogens,
    • evaluate the flux of these microorganisms from land covers to the atmosphere,
    • contribute to research on the role of microorganisms in cloud physics, including processes linked to rainfall, lightning and albedo,
    • assess and map the intensity of land-atmosphere feedbacks mediated by microorganisms.


For the complete and most recent list of publications see ProdInra, the open archive of INRA.

  • Bigg E.K., Soubeyrand S., Morris C.E. 2015 Persistent after-effects of heavy rain on concentrations of ice nuclei and rainfall suggest a biological cause.  Atmos. Chem. Phys. 15: 2313-2326D. DOI : 10.5194/acp-15-2313-2015
  • Bartoli C., Lamichhane J.R., Berge O., Guilbaud C., Varvaro L., Balestra G., Vinatzer B.A., Morris C.E. 2015 A framework to gauge the epidemic potential of plant pathogens in environmental reservoirs: the example of kiwifruit canker.  Mol Plant Pathol 16:137-149. DOI : 10.1111/mpp.12167
  • Berge O., Monteil C.L., Bartoli C., Chandeysson C., Guilbaud C., Sands D.C., Morris C.E.   2014. A user’s guide to a data base of the diversity of Pseudomonas syringae and its application to classifying strains in this phylogenetic complex. PLoS One 9, e105547. DOI : 10.1371/journal.pone.0105547
  • Morris C.E., Conen F., Huffman J.A., Phillips V., Pöschl U., Sands D.C. 2014.  Bioprecipitation: A feedback cycle linking Earth history, ecosystem dynamics and land use through biological ice nucleators in the atmosphere. Global Change Biology 20:341-351 DOI : 10.1111/gcb.12447
  • Morris, C. E., Leyronas C., Nicot P.C. 2014. Movement of bioaerosols in the atmosphere and the consequences for climate and Mmicrobial Eevolution (Chapter 16), p. 393-416. In I. Colbeck and M. Lazaridis (ed.), Aerosol Science: Technology and Applications. John Wiley & Sons, Ltd.
  • Morris C.E., Sands D.C., Glaux C., Samsatly J., Asaad S., Moukahel A.R., Gonçalves F.L.T., Bigg E.K. 2013. Urediospores of rust fungi are ice nucleation active at > −10 °C and harbor ice nucleation active bacteria.  Atmos. Phys. Chem. 13:4223-4233. DOI : 10.5194/acp-13-4223-2013
  • Morris C.E., Monteil C.L., Berge O. 2013. The life history of Pseudomonas syringae: linking agriculture to Earth system processes. Annu. Rev. Phytopath. 51:85-104. DOI : 10.1146/annurev-phyto-082712-102402
  • Morris C.E., Bardin M. Kinkel L.L., Moury B., Nicot P.C., Sands D.C. 2009. Expanding the paradigms of plant pathogen life history and evolution of parasitic fitness beyond agricultural boundaries. PLoS Pathogens 5(12) : e1000693. DOI : 10.1371/journal.ppat.1000693
  • Christner B.C., Morris C.E., Foreman C.M., Cai, R., Sands D.C. 2008. Ubiquity of biological ice nucleators in snowfall. Science 319:1214. DOI : 10.1126/science.1149757