The Rhizosphere team (composed of 3 professors, 3 assistant professors, 1 CNRS associate scientist, and 3 technician staff) works on biotic interactions between soil bacteria and plants. The team’s researches mainly focus on the study of the molecular mechanisms involved in the associative symbiosis (cooperation) between plant beneficial rhizobacteria and plant roots, but has also developed studies on the soil ecology (survival, population dynamics, transfer) of human and plant pathogens. Our originality is to combine (i) approaches at the levels of organisms, populations and communities, and (ii) diversified methods and expertise (soil science, microbial ecology, plant and microbial metabolomics, analysis of plant-microbe interactions through microscopy, monitoring of gene expression, etc). We have developed molecular and genetic studies of plant colonization and plant infection processes by soil bacteria including human pathogens, and monitored the risks associated to these interactions for plants and for humans. Concerning the interaction of human pathogens with plants, the Rhizosphere team has participated since 2005 to 2 national projects focusing on the survival of Escherichia coli subspecies including human pathogens like Shiga-toxin E. coli (STEC) in the soil compartment associated to plant roots (Pastor Project, GESSOL 2, 2005-2008, Co-PI: C. Prigent-Combaret; Acido-résistance STEC Project, ANR PNRA, 2006-2009; PI: C. Vernozy-Rozand). As unexpected, results of these projects showed that E. coli and STEC are able to survive during very long periods of time in bulk (Frémaux et al., 2008) and root-associated soils (Texier et al., 2008; Frémaux et al., 2010; Dorioz et al., 2011; Trévisan et al., 2011), and to finely interact with the plant by colonizing the interior of its tissues and modifying its secondary metabolism (Walker et al. 2013). The team has participated or coordinated EU projects on plant-bacteria interactions. It publishes about 15 research papers per year.

References: Frémaux, B. et al. 2008. Journal of Applied Microbiology 104:296-304.
Texier, S. et al. 2008. Journal of Environmental Quality 37:2299-2310.
Frémaux, B. et al. 2010. Journal of Applied Microbiology 108: 1332-1343.
Trévisan, D. et al. 2010. Water Research 44:3847-3860.
Dorioz, J.-M. et al. 2011. Etude et Gestion des Sols 18:217-236.
Walker, V. et al. 2013. Molecular Plant-Microbe Interactions (In press)

Key words: Ecology, Microbiology, Plant Agronomy, Phytochemistry, Health Risks, Rhizosphere, Rhizobacteria, Pathogens, Plant, Soil, Biotic interactions , Probiotics