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INRA
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

Life history

Ecology of Pseudomonas syringae (from crops to water cycle and back again)

The ongoing research :

  • research of  Pseudomonas syringae in non-agricultural habitats, in interaction with the water cycle,
  • study of the impact of the environmental strains on the development of epidemics in agricultural habitats,
  • measure of the implication of P. syringae in the processes of precipitation, due to the ice nucleating properties of this bacterium

Theses studies are based on the observation that  a major part of the global P. syringae meta-population is in non-agricultural habitats, particularly freshwater habitats.

Reporting of Pseudomonas syringae in non-agricultural habitats

We have reported that a major part of the global P. syringae meta-population is in non-agricultural habitats, particularly freshwater habitats. The distribution of P. syringae across these habitats and the genetic relatedness of strains led us to specify how the life history of this bacterium is linked to the water cycle. Among the reservoirs of P. syringae we identified that leaf litter in sub-alpine zones harbored large populations of P. syringae that are transferred to snowpack during the winter and where the bacterium survives until snow melt. Melt water carries the bacterium through the soil where it feeds into the ground water and eventually is transferred to river water that further disseminates the bacterium and is also used for irrigation.

  • Monteil, C., Guilbaud, C., Glaux, C., Lafolie, F., Soubeyrand, S., Morris, C. 2012. Emigration of the plant pathogen Pseudomonas syringae from leaf litter contributes to its population dynamics in alpine snowpack. Environmental Microbiology, 14, 2099-2112.
  • Monteil, C., Lafolie, F., Laurent, J., Clement, J.-C., Simler, R., Travi, Y., Morris, C. 2014. Soil water flow is a source of the plant pathogen Pseudomonas syringae in subalpine headwaters. Environmental Microbiology, 16, 2038-2052.
  • Morris, C., Monteil, C., Berge, O. 2013. The life history of Pseudomonas syringae: linking agriculture to earth system processes. Annual Review of Phytopathology, 51, 85-104

Genetic diversity of environmental strains of Pseudomonas syringae

Within the large genetic diversity of P. syringae isolated from snowpack and river water, we found effector alleles different from those harboured by strains isolated during epidemics on tomato and kiwi. The environmental strains were nevertheless pathogenic to tomato and kiwi and also had relatively broad host ranges. Because the strains from snowpack and river water were phylogenetically very closely related to those from epidemics, this work showed that crop pathogens may have evolved through a small number of evolutionary events from less aggressive ancestors with a wider host range that are present in non-agricultural environments. A series of stochastic events could lead to the encounter of strains from non-agricultural environments with cultivated plants and to their eventual emergence in disease epidemics. Our work has contributed to the availability of whole genome sequences of strains from non-agricultural habitats currently used in studies of pathogen evolution.

  • Baltrus D., Yourstone S., Lind A., Guilbaud C., Sands D.C., Jones C.D., Morris C.E., Dangl J.L. 2014. Draft genome sequences of a phylogenetically diverse suite of Pseudomonas syringae strains from multiple source populations. Genome Announcements, 2, e01195-13.
  • Bartoli, C., Carrere, S., Lamichhane, J. R., Varvaro, L., Morris, C. E. 2015. Whole-genome sequencing of 10 Pseudomonas syringae strains representing different host range spectra. Genome announcements, 3, e00379-15. 
  • Monteil, C.L., Cai, R.M., Liu, H.J., Llontop, M.E.M., Leman, S., Studholme, D.J., Morris, C.E., and Vinatzer, B.A. 2013. Nonagricultural reservoirs contribute to emergence and evolution of Pseudomonas syringae crop pathogens. New Phytologist, 199, 800-811.
  • See the page on INRA website "Non-agricultural reservoirs contribute to emergence and evolution of crop pathogens"

Effet de Pseudomonas syringae sur les précipitations

Because of the efficient ice nucleation activity of P. syringae at relatively warm temperatures, its dissemination with the water cycle - and particularly the feedback cycle between plants and clouds – has important implications for beneficial effects on rainfall. We have been leading an international interdisciplinary network to elucidate the settings for and extent of this beneficial impact using various social media and shareware tools. Through this work we have brought the idea of bioprecipitation into the realm of very plausible. Bioprecipitation, a feedback cycle between plants and clouds wherein rainfall is induced by ice nucleation active microorganisms from plants, is now an object of expanding research activity worldwide.

A small unmanned aircraft system (sUAS) used to collect microorganisms in the lower atmosphere (Jimenez-Sanchez, C. et al., 2018)

A small unmanned aircraft system (sUAS) used to collect microorganisms in the lower atmosphere (Jimenez-Sanchez, C. et al., 2018)

 

See also

  • From grains to rain: the link between landscape, airborne microorganisms and climate processes
    This e-book edited by Morris, C.E. and Sands, D.C. (2012) can be download on the Biological aerosol nucleators", a scientific forum about organisms that can catalyze the freezing of water and their roles in nature
  • See our web site "Medias": press about the Mistral team